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MATTER ANDMEASUREMENT

Chapter 1

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Chapter Map

What will we cover in this chapter?

Two topics:1. Matter2. Measurements

Before that, we answer the question: What is and why do we study Chemistry?

Matter

What is matter?• Atoms and elements• Compounds• Mixtures

Classification of Matter:• Pure substances (elements and compounds)• Mixtures (homogeneous and heterogeneous)

Properties of Matter:

1. Physical

2. Chemical

A property can be intensive or extensive)

Separation of Mixtures:

Mixtures can be separated while pure substances cannot.

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Measurement

Units (SI)

Measurement of:1. Length2. Mass3. Temperature4. Volume5. density

Uncertainty in Measurements• Precision and accuracy

Expressing Precision Using Significant Figures• Counting significant figures• Calculations using significant figures

Using dimensional analysis to perform calculations:

Definition and use of conversion factors

MATTER ANDMEASUREMENT

Chapter 1

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The Atomic and Molecular view of Chemistry

• Chemistry is the study of the properties and behavior of matter.

• Matter is the physical material of the universe; it is anything that has mass and occupies space.

• A property is any characteristic that allows us to recognize a particular type of matter and to distinguish it from other types.

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• Chemistry also provides the basics for understanding the properties of matter in terms of atoms, the almost infinitesimally small building blocks of matter.

• Experiments have shown that the tremendous variety of matter in our world is due to combinations of only about 100 substances called elements.

• Each element is composed of a unique (one single) kind of atoms.

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Why Study Chemistry?

• Simply because Chemistry greatly impacts our lives!!

• We are talking about Chemistry when studying health problems and efficiency of drugs.

• We are dealing with Chemistry when discussing agricultural products and nutrition, manufacture of cars, planes, paints, cement, cloth, explosives, equipment, etc.

• Everything around us in the physical world is related to Chemistry, that is Chemistry is undoubtedly the Central Science.

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What do Chemists do?

• Chemists can work in industry, government labs and organizations, teaching, supervising, as well as management jobs.

• Mainly, Chemists do three things:1. Make new materials and mixtures of desired

properties2. Measure the properties of matter3. Develop models that explain /predict the

properties of matter

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Elements and Matter• An element is composed of one type of atoms.

e.g. iron, hydrogen, sulfur, etc. It can be monoatomic, or molecular.

• The properties of matter relate to both the kinds of atoms the matter contains (composition) and to the arrangements of these atoms (structure).

• Chemistry is the science that seeks to understand the properties and behavior of matter by studying the properties and behavior of atoms and molecules.

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Molecules and Matter

• In molecules, two or more atoms are joined together in specific shapes. Molecules can be elements or compounds.

• For example, notice that the molecules of ethanol and ethylene glycol have same type of atoms, but different compositions and structures.

• Ethanol contains one oxygen atom, depicted by one red sphere. In contrast, ethylene glycol contains two oxygen atoms.

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Structure and Properties• Even apparently minor differences in the composition or

structure of molecules can cause profound differences in properties.

1. Ethanol, for example, is not toxic while ethylene glycol is toxic.

2. Ethanol has a low viscosity while ethylene glycol is viscous.

3. Ethanol has a low boiling point while ethylene glycol has a high boiling point.

• Every change in the observable world—from boiling water to the changes that occur as our bodies combat invading viruses—has its basis in the world of atoms and molecules.

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Classifications of Matter

A sample of matter can be a gas, a liquid or a solid• A gas (vapor) has the volume and shape of its

container• A liquid has a specific volume but has the shape

of its container• A solid has a specific volume and shape that

does not depend on the container

Neither liquids nor solids can be (appreciably) compressed to smaller volumes

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Gases, Liquids, and Solids

• Gas molecules are very far apart from each other. They collide with the container walls and with one another. Compressing a gas decreases these distances, while placing the gas in a larger container increases the volume and thus distances between molecules.

• In liquids, molecules are packed closely to each other but still move rapidly, thus sliding over one another to be poured.

• In solids, molecules are held tightly together, thus movement is highly restricted.

Changes in temperature and/or pressure can convert a state to another.

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Pure Substances

• A substance can either be an element, a compound, or a mixture.

• Elements are formed from one type of atoms, compounds are composed of two or more types of atoms, while a mixture is composed of two types of elements or compounds, or combinations of elements and compounds.

• A pure substance is one that has distinct properties and composition that does not vary from sample to sample. Air, sea water, drinking water, gasoline, bricks, are not pure substances. However, water (H2O) and salt (NaCl) are pure substances.

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Elements

• Currently, there are 118 elements described in the Chemical literature. These are listed in a Table called the periodic table, which will be studied later.

• Five elements (oxygen, silicon, aluminum, iron, and calcium) account for about 90% of the earth’s crust.

• Only three elements (oxygen, carbon, and hydrogen) account for over 90% of the mass of human body.

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Some Common Elements

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Compounds

• Compounds are substances formed from two or more different elements.

• For example: Water is formed from hydrogen and oxygen

• The formed compounds usually have properties very different from those of the constituent elements

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A Compound: Definite Proportions of Elements (Constant Composition)

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Always 11.11% hydrogen and 88.89% oxygen (by mass) combine to form water and are produced when water is electrolyzed to its elements.

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Comparison of Properties: Compounds versus Elements

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The law of constant composition (or definite proportions) was suggested by French scientist Joseph Louis Proust about 200 years ago.

Mixtures

• When two or more substances (elements or compounds) are mixed together, a mixture is formed.

• When the mixed substances dissolve in each other (no chemical reaction), a homogeneous solution is obtained, like all clear solutions, metallic coins, etc.

• When the mixed substances do not completely dissolve in each other, a heterogeneous solution is obtained, like sand in water, wood in sand or rocks, chalk in water, smoke in air, etc.

• Solutions can be gases, liquids, or solids.

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Distinguishing Elements, Compounds and Mixtures

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“White gold” contains gold and a “white” metal, such as palladium. Two samples of white gold differ in the relative amounts of gold and palladium they contain. Both samples are uniform in composition throughout. Use previous Figure to classify white gold.

Because the material is uniform throughout, it is homogeneous. Because its composition differs in the two samples, it cannot be a compound. Instead, it must be a homogeneous mixture.

Aspirin is composed of 60.0% carbon, 4.5% hydrogen, and 35.5% oxygen by mass, regardless of its source. Use previous Figure to classify aspirin.

It is a compound because it has constant composition and can be separated into several elements.

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Properties of Matter

• Matter has two types of properties:1. Physical properties: these are properties

that can be observed without changing the identity and composition of the substance. Like color, melting point, boiling point, odor, luster, etc.

2. Chemical properties: describe the way a substance may change or react to form other substances. Like combustion.

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Matter and Measurement

Lecture 2

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Intensive and Extensive Properties

• Some properties can be classified as:1. Intensive properties: these are properties that

do not depend on the amount of sample being examined. Intensive properties, like melting point, temperature, density, color, are important because they can be used to identify the substance.

2. Extensive properties: depend on the amount of substance like mass, volume, surface area, energy, etc.

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Physical and Chemical Changes

• A change substances can undergo can either be physical or chemical.

• In a physical change, a substance changes appearance but not composition: like water to ice or vapor.

• In chemical changes, a substance is no longer there as it is converted to something else: like gasoline in an engine is converted to carbon dioxide.

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Examples of a Physical Change

Examples of Chemical Changes

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Example of Chemical Changes

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Separation of Mixtures

• Separation of components of a mixture can be accomplished by taking advantage of the physical properties of these components.

• For example: gold in a heterogeneous mixture of gold and iron powder can be simply recovered by using a magnet to collect iron.

• When one component dissolves in a solvent while the other does not, dissolution and filtration can separate the mixture. Like salt or sugar mixed with other insoluble material.

• Distillation of volatile liquid mixtures will separate them from other substances according to boiling point.

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Separation of a mixture by Filtration

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Separation by Distillation

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Separation by Chromatography

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The scientific method

The scientific method is a dynamic process used to answer questions about our physical world. Observations and experiments lead to scientific laws, which are general rules that summarize how nature behaves. Laws do not explain behavior.

Observations also lead to tentative explanations or hypotheses. As a hypothesis is tested and refined, a theory may be developed that can predict the results of future observations and experiments.

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The Scientific Method

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Units of Measurements

• Many properties of matter are quantitative, that is associated with numbers. When a number represents a measured quantity, the units of that quantity must be specified. To say that the length of a pencil is 17.5 is meaningless. Expressing the number with its units, 17.5 centimeters (cm), properly specifies the length.

• The units used for scientific measurements are those of the metric system.

• The metric system, developed in France during the late eighteenth century, is used as the system of measurement in most countries. The United States has traditionally used the English system, although use of the metric system has become more common.

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SI Units

• In 1960, an international agreement was reached to use certain units, called the SI units.

• The system is also called the metric system• The system has seven base units, as shown in

the following Table.• Other countries like United States and

England still use a less familiar system (lb, in, ft, yd, oz, etc).

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SI Base Units

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Prefixes Used with SI Base Units

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What is the name of the unit that equals (a) 10–9 gram, (b) 10–6 second, (c) 10–3 meter?

We can find the prefix related to each power of ten in the previous table: (a) nanogram, ng, (b) microsecond, μs, (c) millimeter, mm.

(a) How many picometers are there in one meter? (b) Express 6.0 × 103 m using a prefix to replace the power of ten. (c) Use exponential notation to express 4.22 mg in grams. (d) Use decimal notation to express 4.22 mg in grams.

(a) 1012 pm, (b) 6.0 km, (c) 4.22 × 10–3 g, (d) 0.00422 g

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Mass and Weight

• As indicated earlier, the SI unit for mass is the kg• Mass is a quantity describing the amount of

material in an object, which is really constant regardless where this object is.

• The weight of an object, on the other hand, is variable depending on location as it is defined as the force that is exerted on the mass of the object by gravity.

• Therefore, an object has the same mass on earth and moon, while its weight is different.

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Temperature

• Temperature is a measure of the hotness or coldness of an object. It is a physical property that describes the direction of heat flow.

• In this course, we will encounter three temperature scales:

1. The Celsius scale (0-100 oC)

2. The Fahrenheit scale (32-212 oF)

3. The Kelvin scale (273-373 K)

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Relationship Between the Three Temperature Scales

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Conversion between Temperature Scales

• A weather forecaster predicts the temperature will reach 31 oC. What is this temperature in K and oF?

K = 31 + 273 = 304 K

oF = 9/5(31) + 32 = 88 oF

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• Ethylene glycol, used in antifreeze solutions, freezes at -11.5 oC. What is the freezing point in K and oF?

K = -11.5 + 273 = 261.5 K

oF = 9/5(-11.5) + 32 = 11.3 oF

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Volume Measurement

• Volume of solutions and gases can be measured using appropriate glassware.

• In the Chemistry laboratory you will encounter the graduated cylinder, the pipet, the burette, the syringe, the volumetric flask, as well as others.

• The glassware used for volume measurement can differ significantly in both precision and accuracy.

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You should be able to recognize that:

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Which of the following quantities represent volume measurements:

15m2, 2.5*102 m3, 5.77 L/s? How do you know?

Only the quantity 2.5*103 m3 is a volume measurement since the unit in volume measurement is (length)3.

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Derived Units from SI Units

• Units for different quantities can be derived from SI base units, provided that a definition of the quantity is known.

• For example, speed is distance per time, thus its units could be m/s, km/s, km/hr, etc.

• Density is the mass per volume, thus its units can be g/cm3 , g/mL, kg/L, mg/L, etc.

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Densities of Selected Substances at 25 oC

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Examples on Density Calculations

• Calculate the density of a 374.5 g of copper if it has a volume of 41.8 cm3 .

• d = 374.5 g/41.8 = 8.96 g/cm3

• A student needs 15.0 g of ethanol for an experiment. If the density bof ethanol is 0.789 g/mL, how many mL of ethanol are needed?

• mL ethanol = mass/density = 15.0 g/0.789 (g/mL) = 19.01 mL

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Calculate the density of Hg if 1.00*102 g occupies a volume of 7.63 cm3.

d = 1.00*102 g/7.36 cm3 = 13.6 g/cm3

Calculate the volume of 65.0 g of liquid methanol if its density is 0.791 g/cm3.

V = 65.0g/(0.791g/cm3) = 82.2

Calculate the mass of a cube of gold if the length of thyecube is 2.00 cm and its density is 19.32 g/cm3.

Mass = V*d = (2.00 cm)3* (19.32 g/cm3) = 155 g

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Uncertainty in Measurements

• Two kinds of numbers can be reported as data in scientific work:

1. Exact numbers that are always 100% certain, like the number of students in a certain class, the number of hands a person has, the number of experiments a scientist conducted, also a kg is 1000g and 1 meter is 100cm, and a 1 ft is 12 in, etc.

2. Numbers that are results of an experiment, we are not 100% certain of their value, like % gold in an ore, mass of an object (we can have an average mass only), the length of an object, etc.

In the second kind of numbers, a scientist always has to make a guess of the last digit as he will be sure about all digits but the last.

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Which of the following is an inexact quantity:a. Number of people in your classb. The mass of a pennyc. The number of g in a kilogram

The inexact number is the one that is determined from experiment, and thus has some uncertainty in it that if the experiment is repeated, a slightly different value may be obtained.

a. The number of people in class is always the same, regardless how many times we count.

b. The mass of a penny is determined experimentally and thus it contains uncertainty. It is inexact

c. 1 kg always has 1000g

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Precision and Accuracy

• Precision of a measurement is a measure of how close repetitive measurements are as compared to the average. A precise measurement is not necessarily accurate. For example, a person has a mass of 61 kg as indicated by a scale, however, what if the scale gives a low value and reads 61 for a 74 mass!!

• Accuracy is a measure of how close the average is as compared to the correct or accepted value.

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Precision and Accuracy

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Significant Figures

• These are simply the digits that when included in a number they reflect a meaning (they have significance).

• Look at dividing 10.2 by 3.1 where your calculator will give you too many digits (3.290322581) and you should be able to choose how many digit you should report in the answer.

• You should worry about measurements only as the number of significant figures gives an idea about the precision of the measurement and tools utilized in getting the answer.

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Precision

Reproducibility ∼ 0.1 g ∼ 0.0001 g

Precision low high

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Counting Significant Figures

• First you should know that a number can have one uncertain digit only (estimated).

• The uncertain digit is counted as a significant figure• When counting significant figures, start from the first

digit other than zero and start counting to the right.• All zeros to the left of a nonzero digit are not

significant. • All zeros between valued numerical digits are counted

(significant).• Zeros to the right of numeric digits are not significant,

unless a decimal point is present.

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Counting Significant Figures

• The number 00215 has three SFs• The number 02015 or 002105 has four SFs• The number 215000 has three significant figures

and should be written in the scientific notation as 2.15*105

• The number 215.000 has 6 SFs, also the number 2.15000 has six SFs

• The number 0.000215 has only three SFs.• When the answer is an average, the uncertainty

occurs in the very most right digit only.

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Other Examples on SFs

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Reporting Uncertainties

• Assume that an average mass of a ball is 762 g and the uncertainty in the mass is 5g. This is written as (762 + 5)g. Since the uncertain number occurs in the integer, the number can never be written as for example (762 + 0.1)g.

• However, if the average on another balance (more precise one) was 762.4g and the uncertainty in measurement was 0.6g, then the answer is written as (762.4 + 0.6)g.

• Always the last digit (the uncertain one) in a measurement and the uncertainty associated to that value should reflect the same precision.

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• What difference exists between the measured values 4.0 g and 4.00 g?

• The value 4.0 has two significant figures, whereas 4.00 has three. This difference implies that the 4.0 has more uncertainty. A mass reported as 4.0 g indicates that the uncertainty is in the first decimal place. Thus, the mass might be anything between 3.9 and 4.1 g, which we can represent as . A mass reported as 4.00 g indicates that the uncertainty is in the second decimal place. Thus, the mass might be anything between 3.99 and 4.01 g, which we can represent as.

• 4.00 + 0.01g (more precise)• 4.0 + 0.1g (less precise)

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Reading a thermometer

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To the correct number of significant figures, what is the level of the liquid in the buret?

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To the correct number of significant figures, what is the volume of the liquid in the graduated cylinder?

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Each of the numbers in the following calculation represents a quantitymeasured by a student in the laboratory.g = 0.0220 × (1/44.0) × 12.0After performing the calculation, the student's calculator appearedas shown below: To the correct number of significant figures what isthe value of g?

PRACTICE EXERCISE

A sample that has a mass of about 25 g is placed on a balance that has a precision of +0.001g. How many significant figures should be reported for this measurement?

• Answer: five, as in the measurement, the uncertainty being in the third decimal place and we have two integers

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Calculations with SFs

• Just a short introduction will be presented here. Detailed description will be covered in CHEM 2310.

• Addition and subtractionThe measurement with the larger uncertainty will

determine the number of SFs in the answer. Get the uncertainty in a measurement by looking at the number of digits to the right of the decimal point. The highest uncertainties are obtained for a lower number of digits.

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Addition and Subtraction

• Assume you are to sum the following numbers:• 20.42 two digits to the right• 1.322 three digits to the right• 83.1 one digit to the right________________________________• Sum = 104.842• Since the result 83.1 has one digit to the right of

the decimal point, this is the highest uncertainty and the answer should include one digit to the right of the decimal point (answer = 104.8)

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Multiplication and Division

• In multiplication and division, the number with the least number of SFs defines the number of digits in the answer.

• Example• Find the area of a rectangle which has a length of 6.221

cm and a width of 5.2 cm.• Area = (6.221 cm)*(5.2 cm) = 32.3492 cm2 ee 32 cm2

• 5.2 has two SFs only while 6.221 has 4 SFs. The answer should have only 2 SFs, that is 32 cm2 .

• Exact numbers are assumed to have infinite number of SFs.

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Rounding Off

• In rounding off numbers, look at the leftmost digit to be removed:

• If the leftmost digit removed is less than 5, the preceding number is left unchanged.

• Thus, rounding 7.248 to two significant figures gives 7.2.• If the leftmost digit removed is greater than 5, the

preceding number is increased by 1.• If the leftmost digit to be removed is exactly 5, look at the

digit before it, increase it by 1 if it is odd and do not round off it is even

• Rounding 4.735 to three significant figures gives 4.74 (since 3 is odd), and rounding 2.45 to two significant figures gives 2.4 since 4 is even.

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• The width, length, and height of a small box are 15.5 cm, 27.3 cm, and 5.4 cm, respectively. Calculate the volume of the box, using the correct number of significant figures in your answer.

Volume = width * length * height• A calculator used for this calculation shows 2285.01,

which we must round off to two significant figures. • V = (15.5 cm) (27.3 cm) (5.4 cm) = 2285.01 cm3

• Because the resulting number is 2300, it is best reported in exponential notation, to clearly indicate two significant figures.

• Answer = 2.3 * 103 cm3

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• It takes 10.5 s for a sprinter to run 100.00 m. Calculate her average speed in meters per second, and express the result to the correct number of significant figures.

• Speed = distance/time• Speed = (100.00/10.5) = 9.5238095 m/s

• However, time has 3 SFs while distance has 5 SFs. The answer should have only 3 SFs

• Answer = 9.52 m/s

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• A gas at 25 °C fills a container whose volume is 1.05 * 103 cm3. The container plus gas has a mass of 837.6 g. The container, when emptied of all gas, has a mass of 836.2 g. What is the density of the gas at 25 °C?

• Mass of gas = 837.6-836.2 = 1.4g

• Density = mass/volume = 1.4g/(1.05*103 cm3)

• Density = 1.3*10-3 g/cm3

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Dimensional Analysis

• Dimensional analysis is an approach used in solving problems.

• The heart of dimensional analysis is the correct and smart use of conversion factors.

• A conversion factor is a ratio where the numerator is equivalent to denominator. For example: 1m is equivalent to 100 cm, this is written as (1m/100cm) or (100cm/1m), where either factor can be used in solving a problem.

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Other Conversion Factors

• 1kg/1000g or 1000g/1kg• 1g/1000mg or 1000mg/1g• 1ft/12 in or 12 in/1ft• No. of mol/1L or 1L/no. of mol• No. of g/1mL or 1mL/no. of g• 22.4 L of gas/1 mol or 1mol/22.4 L of gas at

STP• So on

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Using Dimensional Analysis• The idea of using dimensional analysis efficiently is as

follows:

1. Start with the given unit(s) by writing it after the equality sign.

2. Look for a conversion factor that has the desired unit or a unit that can be converted to the desired on as the numerator, BUT must have the given unit as the denominator.

3. Repeat step 2 till the desired unit is obtained.

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Two or More Conversion Factors

• To solve some problems, one may need to use two or more conversion factors to get from the given unit to the desired one.

• For example conversion from meters to inches, one can use a conversion factor to convert meters to cm, then another to convert cm to in.

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How many inches are there in 8.00 meters?

First change m to cm, then convert cm to in:

Remember that the terms in the two conversion Factors are exact numbers and should not be used

to calculate the number of significant figures in the answer.

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You can first work with the numerator to convert m to miles, then pay attention to denominator to convert seconds to hrs.

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Conversions Involving Volumes

• Remember:• 1m = 100 cm, therefore 1m3 = (100)3 cm3

• 1L = 1000 cm3

• From above, one can conclude that:1m3 = 1000 L

Therefore, you should be careful when working with volumes

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• The density of gold is 19.3g/cm3 . Report the value of the density as g/in3.

• Density (g/in3) = (19.3g/cm3 )*(2.543 cm3

)/(13 in3) = 316 (g/in3)

How many g are there in 2.00 in3 of gold?

g gold = 2.0 in3*(2.543 cm3 )/(13 in3)*19.3g/cm3

g gold = 633 g

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The density of benzene is 0.879g/mL. What is the mass of 1 qt of benzene in grams?

Convert density from g/mL to g/qt. you can use the factor (1000mL/1L) then (1L/1.057qt), ore simply (1000mL/1.057qt).

g benzene/qt = (0.879g/mL)*(1000mL/1.057qt)

= 832 g

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What is the volume of 5.0 ft3 in cubic meters?

m3 = 5.0 ft3 *(123 in3 /ft3 )*(2.543 cm3 /in3)*(m3

/1003 cm3)

Volume = 0.14 m3

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Chapter 1 Matter and Measurement 1) A theory is a model used to explain natural laws and make predictions about natural phenomena. 2) The scientific method is used to make theories that can no longer be changed. 3) The composition refers to the components of a sample of matter and their relative proportions. 4) A physical property is the ability of a sample of matter to undergo a change in composition under certain conditions. 5) A homogenous mixture has regions that are different in composition or phase. 6) On a very cold day in Alaska, the temperature was -40°F. The temperature in Celsius on the same day was also -40°. 7) The SI unit of mass is 1 gram. 8) An intensive property is dependent of the amount of matter observed. 9) Several values close together guarantee good accuracy. 10) The result of addition can have more significant figures than any of the numbers added. 11) A model that explains and makes predictions about natural phenomena is referred to as a: A) natural law B) hypothesis C) theory D) generalization E) deduction 12) Which of the following is a physical property? A) the density of lead B) sulfur burns in oxygen to form sulfur trioxide C) ozone reacts with silver to give silver oxide D) platinum metal does not react with hydrochloric acid 13) A physical property is: A) the ability of a sample to undergo change B) a substance comprised of a single type of atom C) a property the sample displays without changing its composition D) always visible E) a property the sample displays that results in a change in composition 14) A chemical change always involves a change in: I) appearance II) state III) composition IV) temperature A) I and II

B) I, II, IV C) III only D) II and IV E) all of the above 15) Which of the following is a chemical property of gold? A) does not react with hydrochloric acid B) is a good conductor of electricity C) is malleable D) is a good conductor of heat 16) Which of the following is a physical change? A) the freezing of water to form ice B) the burning of paper C) the mixing of salt and water D) the reaction of zinc with hydrochloric acid E) the inability of gold to react with water 27) Oxygen is: A) a mixture B) a compound C) an element D) a solution E) always combined with hydrogen 18) Sulfur dioxide gas is: A) a homogeneous mixture B) a compound C) an element D) a heterogeneous mixture E) a solid at room temperature 19) Sulfuric acid is: A) a homogeneous mixture B) a compound C) an element D) a heterogeneous mixture E) an atom 20) The term substance should be used for A) chemical elements B) compounds C) both chemical elements and compounds D) chemical elements, compounds, and mixtures E) any mixture. 21) Choose the INCORRECT statement. A) Matter is made of tiny units called atoms. B) An element is a substance made of one type of atom. C) A compound contains regions that are unlike other regions of the compound.

D) Homogeneous mixtures are solutions. E) Elements and compounds are substances. 22) Which of the following are forms of matter? I) hydrogen gas II) sunlight III) ice IV) wind V) iron A) III and V B) I, III and V C) I and V D) II and IV E) all of the above 23) Which one of the following would be classified as a heterogeneous mixture? A) salt water B) copper nitrate solution C) brass D) mix of table salt and black pepper E) a sugar solution 24) Which of the following is a chemical change? A) the freezing of water to form ice B) hammering zinc into a thin film C) the inability of gold to react with water D) the boiling of water to form steam E) the reaction of chlorine gas and sodium to form salt 25) From ammonia gas, one can obtain two different gases, each of which is a pure substance. Using only this information, it can be said with certainty that: A) one of the products is an element B) neither of the products can be an element C) ammonia cannot be an element D) both products are elements E) gases do not produce solids 26) Which of the following is a compound? A) water B) oxygen C) heat D) salad dressing E) nitrogen 27) The content of a container filled with sand and water would best be described as: A) elements B) a homogeneous mixture C) a heterogeneous mixture D) a compound E) a solution

28) Water is: A) a mixture B) a compound C) an element D) a molecule E) an atom 29) Saltwater is: A) a mixture B) only one compound C) an element D) a molecule E) an atom 30) In the following list, only __________ is not an example of matter. A) planets B) light C) dust D) elemental phosphorus E) table salt 31) What is the physical state in which matter has no specific shape but does have a specific volume? A) gas B) solid C) liquid D) salts E) ice 32) The law of constant composition applies to __________. A) solutions B) heterogeneous mixtures C) compounds D) homogeneous mixtures E) solids 33) A combination of sand, salt, and water is an example of a __________. A) homogeneous mixture B) heterogeneous mixture C) compound D) pure substance E) solid 34) A small amount of salt dissolved in water is an example of a __________. A) homogeneous mixture B) heterogeneous mixture C) compound D) pure substance E) solid

35) Which one of the following has the element name and symbol correctly matched? A) P, potassium B) C, copper C) Mg, manganese D) Ag, silver E) Sn, silicon 36) Which one of the following has the element name and symbol correctly matched? A) S, sodium B) Tn, tin C) Fe, iron D) N, neon E) B, bromine 37) Which one of the following elements has a symbol that is not derived from its foreign name? A) tin B) aluminum C) mercury D) copper E) lead 38) Which one of the following is a pure substance? A) concrete B) wood C) salt water D) elemental copper E) milk 39) Which one of the following is often easily separated into its components by simple techniques such as filtering or decanting? A) heterogeneous mixture B) compounds C) homogeneous mixture D) elements E) solutions 40) Which states of matter are significantly compressible? A) gases only B) liquids only C) solids only D) liquids and gases E) solids and liquids 41) For which of the following can the composition vary? A) pure substance B) element C) both homogeneous and heterogeneous mixtures D) homogeneous mixture E) heterogeneous mixture

42) If matter is uniform throughout and cannot be separated into other substances by physical means, it is __________. A) a compound B) either an element or a compound C) a homogeneous mixture D) a heterogeneous mixture E) an element 43) An element cannot __________. A) be part of a heterogeneous mixture B) be part of a homogeneous mixture C) be separated into other substances by chemical means D) interact with other elements to form compounds E) be a pure substance 44) Homogeneous mixtures are also known as __________. A) solids B) compounds C) elements D) substances E) solutions 45) The law of constant composition says __________. A) that the composition of a compound is always the same B) that all substances have the same composition C) that the composition of an element is always the same D) that the composition of a homogeneous mixture is always the same E) that the composition of a heterogeneous mixture is always the same 46) Which of the following is an illustration of the law of constant composition? A) Water boils at 100°C at 1 atm pressure. B) Water is 11% hydrogen and 89% oxygen by mass. C) Water can be separated into other substances by a chemical process. D) Water and salt have different boiling points. E) Water is a compound. 47) In the following list, only __________ is not an example of a chemical reaction. A) dissolution of a penny in nitric acid B) the condensation of water vapor C) a burning candle D) the formation of polyethylene from ethylene E) the rusting of iron 48) Of the following, only __________ is a chemical reaction. A) melting of lead B) dissolving sugar in water C) tarnishing of silver D) crushing of stone E) dropping a penny into a glass of water

49) Which one of the following is not an intensive property? A) density B) temperature C) melting point D) mass E) boiling point 50) Which one of the following is an intensive property? A) mass B) temperature C) heat content D) volume E) amount 51) Of the following, only __________ is an extensive property. A) density B) mass C) boiling point D) freezing point E) temperature 52) Which of the following are chemical processes? 1. rusting of a nail 2. freezing of water 3. decomposition of water into hydrogen and oxygen gases 4. compression of oxygen gas A) 2, 3, 4 B) 1, 3, 4 C) 1, 3 D) 1, 2 E) 1, 4 53) In the following list, only __________ is not an example of a chemical reaction. A) burning a plastic water bottle B) the production of hydrogen gas from water C) the tarnishing of a copper penny D) chopping a log into sawdust E) charging a cellular phone 54) A consistent explanation of known observations is called A) an experiment. B) a hypothesis. C) a prediction. D) a theory. 55) An interpretation of the results of many tests is called A) an experiment. B) a hypothesis. C) a prediction.

D) a theory. 56) The fundamental SI unit of mass is the A) centigram. B) gram. C) kilogram. D) milligram. 57) Which of the following is a fundamental SI Unit? A) centimeter B) kilogram C) microsecond D) milliliter 58) All of the following are fundamental SI units except the A) gram. B) Kelvin. C) meter. D) second. 59) What symbol is used to express the factor, 10-6? A) M B) m C) μ D) n 60) What symbol is used to represent the factor 10-3? A) M B) m C) μ D) n 61) What symbol is used to represent the factor 10-9? A) M B) m C) μ D) n 62) The factor 0.01 corresponds to which prefix? A) deka B) deci C) centi D) milli 63) Convert 5.100 × 10-3 to ordinary notation. A) 0.0005100 B) 0.005100 C) 510.0 D) 5100

64) Convert 0.003002 to standard scientific notation. A) 3.002 × 10-3 B) 3002 × 10-6 C) 3.002 × 103 D) 3002 × 106 65) Without using a calculator, solve the following problem:

A) 1 × 10-6 B) 1 × 104 C) 1 × 1024 D) 1 × 1034 66) Without using a calculator, solve the following problem:

A) 1 × 100 B) 1 × 10-3 C) 1 × 10-9 D) 1 × 10-12 67) An astronaut uses a laboratory balance and weighs an object on earth and again on the moon. Which statement below about the weight and mass of the object is true? A) The mass and weight will be identical on the earth and the moon. B) The mass will be the same on earth and moon but the weight will be less on the moon. C) The weight will be the same on earth and moon but the mass will be less on the moon. D) Both the mass and weight will be different on earth and moon. 68) When measuring a solid metal block at constant temperature, which measurement will change in numerical value depending on the location where it is taken? A) length B) mass C) volume D) weight 69) Which of the following is the greatest mass? A) 1000 μg B) 1.000 × 10-4 kg C) 1.000 × 10-2 cg D) 1.000 × 10-8 Mg 70) The mass of a single copper atom is 1.055 × 10-22 g. This is the same mass as A) 1.055 × 10-16 mg. B) 1.055 × 10-25 kg.

C) 1.055 × 10-28 μg. D) 1.055 × 10-31 ng. 71) A student weighed 3000. μg of sulfur in the lab. This is the same mass as A) 3.000 × 10-6 g. B) 3.000 × 10-3 kg. C) 3.000 × 103 mg. D) 3.000 × 106 ng. 71) Convert 1 μm to meters. A) 1 × 10-9 m B) 1 × 10-6 m C) 1 × 10-3 m D) 1 × 106 m 72) The average distance between nitrogen and oxygen atoms is 115 pm in a compound called nitric oxide. What is this distance in centimeters? A) 1.15 × 10-9 cm B) 1.15 × 10-8 cm C) 1.15 × 1012 cm D) 1.15 × 1016 cm 73) The diameter of an atom is approximately 1 × 10-10 m. What is the diameter in millimeters? A) 1 × 10-16 mm B) 1 × 10-13 mm C) 1 × 10-7 mm D) 1 × 10-4 mm 74) The diameter of the nucleus of an atom is approximately 1 × 10-15 meters. If 1 nm is equal to 10 Ångstroms, what is the diameter of the nucleus in Ångstroms? A) 1 × 10-23 Å B) 1 × 10-8 Å C) 1 × 10-7 Å D) 1 × 10-5 Å 75) If the melting point of titanium metal is 1672°C, what is its melting point in Kelvins? A) 897 K B) 1399 K C) 1945 K D) 3042 K 76) Which of the following is the lowest temperature? A) 37°C B) 54°F C) 313 K D) All of these temperatures are all equal.

77) Which one of the following statements about temperature scales is false? A) The boiling point of water on the Fahrenheit scale is 212 degrees. B) The Celsius degree is smaller than the Fahrenheit degree. C) The freezing point of water on the Celsius scale is 0 degrees. D) All temperatures on the Kelvin scale are positive numbers. 78) Which of the following volumes is equal to 10 mL? A) 10 cm3 B) 10 dm3 C) 0.10 L D) 0.00010 kL 79) Convert 100 cm3 to m3. A) 1 × 10-4 m3 B) 1 × 100 m3 C) 1 × 104 m3 D) 1 × 108 m3 80) Convert 15 m3 to liters. A) 1.5 × 10-2 L B) 1.5 L C) 1.5 × 102 L D) 1.5 × 104 L 81) Which of the following is the smallest volume? A) 44 cm3 B) 1.0 dL C) 5.5 × 103 mL D) 1 × 108 nL 82) A piece of metal ore weighs 8.25 g. When a student places it into a graduated cylinder containing water, the liquid level rises from 21.25 mL to 26.47 mL. What is the density of the ore? A) 0.312 g/mL B) 0.633 g/mL C) 1.58 g/mL D) 3.21 g/mL 83) The density of aluminum is 2.702 g/cm3. What is the final liquid level of water if 1.130 ounces of aluminum is dropped into a graduated cylinder containing 15.90 mL of water? A) 17.08 mL B) 21.66 mL C) 27.76 mL D) 47.95 mL 84) The density of mercury is 13.5 g/mL. What is the mass in kg of mercury that fills a 0.250-L flask? A) 0.0540 kg B) 3.38 kg

C) 54.0 kg D) 3380 kg 85) The density of copper is 8.96 g/cm3. What is the mass in mg of a cube of copper that measures 2.31 mm on each side? A) 0.0207 g B) 0.110 g C) 2.07 g D) 110 g 86) Which of the following numbers has the greatest number of significant figures? A) 0.5070 B) 0.201 C) 418000 D) 6.02 × 1024 97) Which of the following is an exact number? A) 0.507 grams B) 1.13 liters C) 2 people D) 5.37°C 88) The measured mass of a sample of iron was 1.23 g. Which digit in the measurement has the least certainty? A) the first digit, 1 B) the middle digit, 2 C) the last digit, 3 D) They are all certain digits. 92) How many of the following numbers contain 3 significant figures? 0.105 6.010 0.0100 8.00 × 102 A) one B) two C) three D) four 89) How many significant figures are there in the answer to the following problem? (8.881 × 2.100) + 0.590 = ? A) one B) two C) three D) four 90) How many significant figures are there in the answer for the following problem? 23.1 + 0.5588 + 17 = ? A) one B) two C) three D) four

95) How many significant figures are there in the answer for the following problem?

[(131.7 119) 1.05]0.500− × = ?

A) one B) two C) three D) four 91) A propane molecule contains 3 atoms of carbon. The number 3 represents how many significant figures? A) one B) two C) three D) infinite 92) Round off 507,506 to four significant figures. A) 5075 B) 5076 C) 5.075 × 105 D) 5.076 × 105 93) Round off 507,506 to three significant figures. A) 507 B) 508 C) 5.07 × 105 D) 5.08 × 105 94) Each of the numbers in the following calculation represents a quantity measured by a student in the laboratory.

P = 0.1000 0.08206 298.151.0068

× ×

After performing the calculation, the student's calculator appeared as shown below: To the correct number of significant figures what is the value of P?

A) 2 B) 2.43 C) 2.430 D) 2.430094 95) Each of the numbers in the following calculation represents a quantity measured by a student in the laboratory.

g = 0.0220 × 144.0

× 12.0

After performing the calculation, the student's calculator appeared as shown below: To the correct number of significant figures what is the value of g?

A) 6 × 10-3 B) 6.0 × 10-3 C) 6.00 × 10-3 D) 6.000 × 10-3 96) To the correct number of significant figures, an automobile traveling at 28 mi/h is traveling at ________ km/h (1 km = 0.6214 mi). A) 17 B) 17.40 C) 45 D) 45.06

97) An automobile uses gasoline at a rate of 35 mi/gal, which is the same as ________ km/L (1 km = 0.6214 mi, 1 gal = 3.78 L). A) 5.8 B) 15 C) 82 D) 210 98) Use the drawings below to answer the following questions.

If hitting the bull's-eye is the desired result, Figure (a) represents A) good accuracy and good precision. B) good accuracy and poor precision. C) poor accuracy and good precision. D) poor accuracy and poor precision. 99) If hitting the bull's-eye is the desired result, Figure (b) represents A) good accuracy and good precision. B) good accuracy and poor precision. C) poor accuracy and good precision. D) poor accuracy and poor precision. 100) If hitting the bull's-eye is the desired result, Figure (c) represents A) good accuracy and good precision. B) good accuracy and poor precision. C) poor accuracy and good precision. D) poor accuracy and poor precision. 101) To the correct number of significant figures, what is the temperature reading on the following Celsius thermometer?

A) 21°C B) 21.7°C C) 21.70°C D) 22°C 102) To the correct number of significant figures, what is the temperature reading on the following Celsius thermometer?

A) 15°C B) 15.6°C C) 15.67°C D) 16°C 103) To the correct number of significant figures, what is the volume of the liquid in the graduated cylinder?

A) 7 mL B) 7.0 mL C) 7.7 mL D) 8 mL

104) To the correct number of significant figures, what is the level of the liquid in the buret?

A) 0.2 mL B) 0.29 mL C) 0.3 mL D) 0.35 mL