Kimia Dasar Chap.1

8/12/2019 Kimia Dasar Chap.1

1/56

1 Introduction

Matter and Measurement


2/56

Outlines1. The Study of Chemistry2. Classification of Matter

3. Properties of Matter4. Units of Measurements

5. Uncertainty in Measurements

6. Dimensional Analysis


3/56

The Study of Chemistry Chemistryis the study ofmatterand the

changes that matter undergoes. Matter is made up of almostinfinitesimally small

building blocks calledatoms. Atoms can combine together to formmolecules. Molecules of a few familiar substances are

represented here. In later chapters you will learn more about how

atoms combine to form molecules, and howmolecules have the shapes and properties thatthey do.
http://localhost/var/www/apps/conversion/tmp/scratch_7/CentralScienceLive/Chapter01/CH01_1.1_Main.htmlhttp://localhost/var/www/apps/conversion/tmp/scratch_7/CentralScienceLive/Chapter01/CH01_1.1_Main.htmlhttp://localhost/var/www/apps/conversion/tmp/scratch_7/CentralScienceLive/Chapter01/CH01_1.1_Main.htmlhttp://localhost/var/www/apps/conversion/tmp/scratch_7/CentralScienceLive/Chapter01/CH01_1.1_Main.htmlhttp://localhost/var/www/apps/conversion/tmp/scratch_7/CentralScienceLive/Chapter01/CH01_1.1_Main.htmlhttp://localhost/var/www/apps/conversion/tmp/scratch_7/CentralScienceLive/Chapter01/CH01_1.1_Main.htmlhttp://localhost/var/www/apps/conversion/tmp/scratch_7/CentralScienceLive/Chapter01/CH01_1.1_Main.htmlhttp://localhost/var/www/apps/conversion/tmp/scratch_7/CentralScienceLive/Chapter01/CH01_1.1_Main.htmlhttp://localhost/var/www/apps/conversion/tmp/scratch_7/CentralScienceLive/Chapter01/CH01_1.1_Main.html


4/56

The Study of Chemistry


5/56

Classification of Matter Mattercan exist in one of three states ofmatter: a gas, a liquid, or a solid.

A gasis highly compressible and will assume

both the shape and the volume of its container. A liquidis not compressible and will assume the

shape but not the volume of its container. A solidalso is not compressible, and it has a

fixed volume and shape of its own.
http://localhost/var/www/apps/conversion/tmp/scratch_7/CentralScienceLive/Chapter01/CH01_1.2_Main.htmlhttp://localhost/var/www/apps/conversion/tmp/scratch_7/CentralScienceLive/Chapter01/CH01_1.2_Main.htmlhttp://localhost/var/www/apps/conversion/tmp/scratch_7/CentralScienceLive/Chapter01/CH01_1.2_Main.htmlhttp://localhost/var/www/apps/conversion/tmp/scratch_7/CentralScienceLive/Chapter01/CH01_1.2_Main.htmlhttp://localhost/var/www/apps/conversion/tmp/scratch_7/CentralScienceLive/Chapter01/CH01_1.2_Main.htmlhttp://localhost/var/www/apps/conversion/tmp/scratch_7/CentralScienceLive/Chapter01/CH01_1.2_Main.htmlhttp://localhost/var/www/apps/conversion/tmp/scratch_7/CentralScienceLive/Chapter01/CH01_1.2_Main.htmlhttp://localhost/var/www/apps/conversion/tmp/scratch_7/CentralScienceLive/Chapter01/CH01_1.2_Main.htmlhttp://localhost/var/www/apps/conversion/tmp/scratch_7/CentralScienceLive/Chapter01/CH01_1.2_Main.htmlhttp://localhost/var/www/apps/conversion/tmp/scratch_7/CentralScienceLive/Chapter01/CH01_1.2_Main.htmlhttp://localhost/var/www/apps/conversion/tmp/scratch_7/CentralScienceLive/Chapter01/CH01_1.2_Main.html


6/56

Classification of Matter Matter can also be classified according to itscomposition.

Most of the matter that we encounter exists in

mixtures, which are combinations of two ormore substances. Mixtures can be homogeneousor

heterogeneous. Mixtures can be separated into pure

substances,and pure substances can be eithercompounds or elements.
http://localhost/var/www/apps/conversion/tmp/scratch_7/CentralScienceLive/Chapter01/CH01_1.2_Main.htmlhttp://localhost/var/www/apps/conversion/tmp/scratch_7/CentralScienceLive/Chapter01/CH01_1.2_Main.htmlhttp://localhost/var/www/apps/conversion/tmp/scratch_7/CentralScienceLive/Chapter01/CH01_1.2_Main.htmlhttp://localhost/var/www/apps/conversion/tmp/scratch_7/CentralScienceLive/Chapter01/CH01_1.2_Main.htmlhttp://localhost/var/www/apps/conversion/tmp/scratch_7/CentralScienceLive/Chapter01/CH01_1.2_Main.htmlhttp://localhost/var/www/apps/conversion/tmp/scratch_7/CentralScienceLive/Chapter01/CH01_1.2_Main.htmlhttp://localhost/var/www/apps/conversion/tmp/scratch_7/CentralScienceLive/Chapter01/CH01_1.2_Main.htmlhttp://localhost/var/www/apps/conversion/tmp/scratch_7/CentralScienceLive/Chapter01/CH01_1.2_Main.htmlhttp://localhost/var/www/apps/conversion/tmp/scratch_7/CentralScienceLive/Chapter01/CH01_1.2_Main.htmlhttp://localhost/var/www/apps/conversion/tmp/scratch_7/CentralScienceLive/Chapter01/CH01_1.2_Main.htmlhttp://localhost/var/www/apps/conversion/tmp/scratch_7/CentralScienceLive/Chapter01/CH01_1.2_Main.htmlhttp://localhost/var/www/apps/conversion/tmp/scratch_7/CentralScienceLive/Chapter01/CH01_1.2_Main.htmlhttp://localhost/var/www/apps/conversion/tmp/scratch_7/CentralScienceLive/Chapter01/CH01_1.2_Main.htmlhttp://localhost/var/www/apps/conversion/tmp/scratch_7/CentralScienceLive/Chapter01/CH01_1.2_Main.htmlhttp://localhost/var/www/apps/conversion/tmp/scratch_7/CentralScienceLive/Chapter01/CH01_1.2_Main.htmlhttp://localhost/var/www/apps/conversion/tmp/scratch_7/CentralScienceLive/Chapter01/CH01_1.2_Main.htmlhttp://localhost/var/www/apps/conversion/tmp/scratch_7/CentralScienceLive/Chapter01/CH01_1.2_Main.htmlhttp://localhost/var/www/apps/conversion/tmp/scratch_7/CentralScienceLive/Chapter01/CH01_1.2_Main.htmlhttp://localhost/var/www/apps/conversion/tmp/scratch_7/CentralScienceLive/Chapter01/CH01_1.2_Main.html


7/56

Classification of Matter A familiar example of a mixture is saltwater.

A sample of salt water has the same

composition throughout. It can be separated into pure

substanceswater and ordinary tablesaltby a physical process, such asdistillation.


8/56

Classification of Matter Pure water is collected in the flask on the right. When all of the water has been distilled from

the mixture, pure saltNaClwill remain in theflask on the left.

Both water and salt are pure substances. They cannot be further separated into simpler

substances by any physical process. Each, however, can be decomposed into other

substances by a chemical process, namelyelectrolysis.

electrolysis
http://localhost/var/www/apps/conversion/tmp/BBAnimations/elec_h20.movhttp://localhost/var/www/apps/conversion/tmp/BBAnimations/elec_h20.mov


9/56

Classification of Matter The substances produced by the electrolysis ofwater cannot be further separated by anyphysical or chemical means.

Oxygen and hydrogen are elements. When water is separated into its constituent

elements, the relative amounts of thoseelements are always the same.

Water is 11 percent hydrogen and 89 percent

oxygen by mass.
http://localhost/var/www/apps/conversion/tmp/scratch_7/CentralScienceLive/Chapter01/CH01_1.2_Main.htmlhttp://localhost/var/www/apps/conversion/tmp/scratch_7/CentralScienceLive/Chapter01/CH01_1.2_Main.html


10/56

Classification of Matter This is an example of the law of constantcomposition, also known as the law of definiteproportions.

Salt can also be separated into itsconstituentelements, sodium and chlorine, by electrolysis. Sodium chloride also has a constant composition,

as do all pure substances. It is 39 percent sodium and 61 percent chlorine

by mass.
http://localhost/var/www/apps/conversion/tmp/scratch_7/CentralScienceLive/Chapter01/CH01_1.2_Main.htmlhttp://localhost/var/www/apps/conversion/tmp/scratch_7/CentralScienceLive/Chapter01/CH01_1.2_Main.htmlhttp://localhost/var/www/apps/conversion/tmp/scratch_7/CentralScienceLive/Chapter01/CH01_1.2_Main.htmlhttp://localhost/var/www/apps/conversion/tmp/scratch_7/CentralScienceLive/Chapter01/CH01_1.2_Main.htmlhttp://localhost/var/www/apps/conversion/tmp/scratch_7/CentralScienceLive/Chapter01/CH01_1.2_Main.htmlhttp://localhost/var/www/apps/conversion/tmp/scratch_7/CentralScienceLive/Chapter01/CH01_1.2_Main.htmlhttp://localhost/var/www/apps/conversion/tmp/scratch_7/CentralScienceLive/Chapter01/CH01_1.2_Main.htmlhttp://localhost/var/www/apps/conversion/tmp/scratch_7/CentralScienceLive/Chapter01/CH01_1.2_Main.htmlhttp://localhost/var/www/apps/conversion/tmp/scratch_7/CentralScienceLive/Chapter01/CH01_1.2_Main.htmlhttp://localhost/var/www/apps/conversion/tmp/scratch_7/CentralScienceLive/Chapter01/CH01_1.2_Main.htmlhttp://localhost/var/www/apps/conversion/tmp/scratch_7/CentralScienceLive/Chapter01/CH01_1.2_Main.htmlhttp://localhost/var/www/apps/conversion/tmp/scratch_7/CentralScienceLive/Chapter01/CH01_1.2_Main.html


11/56

Matter Classification

SchemeMatterIs it uniformthroughout?

Heterogeneousmixture

Homogeneous

Can it beseparated by

physical means?

Homogeneousmixt. (solutn)

Puresubstance

Can it be decomposedinto other substances by

chemical processes?

Element Compound

YES

YES

YES

NO

NO

NO


12/56

Properties of Matter Different types of matter have

different distinguishing characteristicsthat we can use to tell them apart.

These characteristics are called physicalpropertiesand chemical properties.

Physical and chemical properties may be

intensiveor extensive.
http://localhost/var/www/apps/conversion/tmp/scratch_7/CentralScienceLive/Chapter01/CH01_1.3_Main.htmlhttp://localhost/var/www/apps/conversion/tmp/scratch_7/CentralScienceLive/Chapter01/CH01_1.3_Main.htmlhttp://localhost/var/www/apps/conversion/tmp/scratch_7/CentralScienceLive/Chapter01/CH01_1.3_Main.htmlhttp://localhost/var/www/apps/conversion/tmp/scratch_7/CentralScienceLive/Chapter01/CH01_1.3_Main.htmlhttp://localhost/var/www/apps/conversion/tmp/scratch_7/CentralScienceLive/Chapter01/CH01_1.3_Main.htmlhttp://localhost/var/www/apps/conversion/tmp/scratch_7/CentralScienceLive/Chapter01/CH01_1.3_Main.htmlhttp://localhost/var/www/apps/conversion/tmp/scratch_7/CentralScienceLive/Chapter01/CH01_1.3_Main.htmlhttp://localhost/var/www/apps/conversion/tmp/scratch_7/CentralScienceLive/Chapter01/CH01_1.3_Main.htmlhttp://localhost/var/www/apps/conversion/tmp/scratch_7/CentralScienceLive/Chapter01/CH01_1.3_Main.htmlhttp://localhost/var/www/apps/conversion/tmp/scratch_7/CentralScienceLive/Chapter01/CH01_1.3_Main.html


13/56

Properties of Matter Intensive properties such as density,

color, and boiling point do not depend onthe size of the sample of matter and canbe used to identify substances.

Extensive properties such as massandvolume do depend on the quantity of the

sample.


14/56

Properties of Matter Physical properties are those that we candetermine without changing the identityof the substance we are studying.

For instance, we can observe or measurethe physical properties of sodium metal.

It is a soft, lustrous, silver-coloredmetal with a relatively low melting pointand low density.


15/56

Properties of Matter Hardness, color, melting point and

density are all physical properties.

Figure 7.15 shows a chunk ofmetallic sodium, which is softenough to be cut with a knife.


16/56

Properties of Matter

Figure 7.15


17/56

Properties of Matter Chemical properties describe the

way a substance can change or react

to form other substances. These properties, then, must be

determined using a process that

changes the identity of thesubstance of interest.


18/56

Properties of Matter One of the chemical properties of

alkali metals such as sodium and

potassium is that they react withwater.

To determine this, though, we would

have to combine an alkali metal withwater and observe what happens.


19/56

Properties of Matter

Sodium and Potassium in Water


20/56

Properties of Matter Sodium metal (Na) reacts rather

vigorously with water to produce sodiumhydroxide (NaOH) and hydrogen gas(H2).

After the reaction has occurred,although we now have evidence of one of

sodium metal's chemical properties, weno longer havesodium metal.


21/56

Properties of Matter Potassium reacts even more vigorously withwater to produce potassium hydroxide (KOH)and hydrogen gas.

As with sodium, once we have determined achemical property of potassium metal, we nolonger have potassium metal.

To determine the chemical properties of asubstance, it is necessary to change the

substance's chemical identity.


22/56

Properties of Matter The changes undergone by sodium and

potassium when they react with waterare chemical changes, also known aschemical reactions.

Matter can also undergo physicalchangesin which the chemical identity of

the matter does not change.
http://localhost/var/www/apps/conversion/tmp/scratch_7/CentralScienceLive/Chapter01/CH01_1.3_Main.htmlhttp://localhost/var/www/apps/conversion/tmp/scratch_7/CentralScienceLive/Chapter01/CH01_1.3_Main.htmlhttp://localhost/var/www/apps/conversion/tmp/scratch_7/CentralScienceLive/Chapter01/CH01_1.3_Main.htmlhttp://localhost/var/www/apps/conversion/tmp/scratch_7/CentralScienceLive/Chapter01/CH01_1.3_Main.htmlhttp://localhost/var/www/apps/conversion/tmp/scratch_7/CentralScienceLive/Chapter01/CH01_1.3_Main.htmlhttp://localhost/var/www/apps/conversion/tmp/scratch_7/CentralScienceLive/Chapter01/CH01_1.3_Main.htmlhttp://localhost/var/www/apps/conversion/tmp/scratch_7/CentralScienceLive/Chapter01/CH01_1.3_Main.htmlhttp://localhost/var/www/apps/conversion/tmp/scratch_7/CentralScienceLive/Chapter01/CH01_1.3_Main.html


23/56

Properties of Matter One example of a physical change is the

melting of a solid.

When ice melts, it changes from a solidstate to a liquid state, but its chemicalidentity (H2O) is unchanged.

All changes of stateare physical

changes.


24/56

Units of Measurements The scientific community uses SI

unitsfor measurement of such

properties as mass, length, andtemperature.

There are seven SI base units from

which all other necessary units arederived.
http://localhost/var/www/apps/conversion/tmp/scratch_7/CentralScienceLive/Chapter01/CH01_1.4_Main.htmlhttp://localhost/var/www/apps/conversion/tmp/scratch_7/CentralScienceLive/Chapter01/CH01_1.4_Main.htmlhttp://localhost/var/www/apps/conversion/tmp/scratch_7/CentralScienceLive/Chapter01/CH01_1.4_Main.htmlhttp://localhost/var/www/apps/conversion/tmp/scratch_7/CentralScienceLive/Chapter01/CH01_1.4_Main.html


25/56

Units of Measurements


26/56

Units of Measurements Although the meter is the base SI unit used forlength, it may not be convenient to report thelength of an extremely small object or anextremely large object in units of meters.

Decimal prefixes allow us to choose a unit thatis appropriate to the quantity being measured. Thus, a very small object might best be

measured in millimeters (1 millimeter = 0.001meters), while a large distance might best be

measured in kilometers (1 kilometer = 1000meters).


27/56



28/56

Units of Measurements The SI unit of temperature is the kelvin,although the Celsius scaleis also commonlyused.

The Kelvin scaleis known as the absolutetemperature scale, with 0 K being the lowesttheoretically attainable temperature.

K = C + 273.15

Figure 1.18 shows a comparison of the Kelvin,Celsius, and Fahrenheit scales.
http://localhost/var/www/apps/conversion/tmp/scratch_7/CentralScienceLive/Chapter01/CH01_1.4_Main.htmlhttp://localhost/var/www/apps/conversion/tmp/scratch_7/CentralScienceLive/Chapter01/CH01_1.4_Main.htmlhttp://localhost/var/www/apps/conversion/tmp/scratch_7/CentralScienceLive/Chapter01/CH01_1.4_Main.htmlhttp://localhost/var/www/apps/conversion/tmp/scratch_7/CentralScienceLive/Chapter01/CH01_1.4_Main.htmlhttp://localhost/var/www/apps/conversion/tmp/scratch_7/CentralScienceLive/Chapter01/CH01_1.4_Main.html


29/56



30/56

Units of Measurements Note that there are no units of volume inTable 1.4.

For measurements of volume, density,

and other properties, we must derive thedesired units from SI base units.

In the case of volume, which has units oflength cubed, (length)3, the basic SI unit

for volume is the cubic meter (m3).


31/56


32/56

Uncertainty in

Measurements Even the most carefully taken

measurements are always inexact.

This can be a consequence ofinaccurately calibrated instruments,human error, or any number of

other factors.


33/56

Uncertainty in

Measurements Two terms are used to describe thequality ofmeasurements: precisionandaccuracy.

Precision is a measure of how closelyindividual measurements agree with oneanother.

Accuracy refers to how closelyindividually measured numbers agree withthe correct or "true" value.
http://localhost/var/www/apps/conversion/tmp/scratch_7/CentralScienceLive/Chapter01/CH01_1.5_Main.htmlhttp://localhost/var/www/apps/conversion/tmp/scratch_7/CentralScienceLive/Chapter01/CH01_1.5_Main.htmlhttp://localhost/var/www/apps/conversion/tmp/scratch_7/CentralScienceLive/Chapter01/CH01_1.5_Main.htmlhttp://localhost/var/www/apps/conversion/tmp/scratch_7/CentralScienceLive/Chapter01/CH01_1.5_Main.htmlhttp://localhost/var/www/apps/conversion/tmp/scratch_7/CentralScienceLive/Chapter01/CH01_1.5_Main.htmlhttp://localhost/var/www/apps/conversion/tmp/scratch_7/CentralScienceLive/Chapter01/CH01_1.5_Main.html


34/56

Uncertainty in

Measurements


35/56

Uncertainty in

Measurements Whatever the source, all measurementscontain error.

Thus, all measured numbers containuncertainty.

It is important that these numbers bereported in such a way as to convey the

magnitude of this uncertainty.


36/56

Uncertainty in

Measurements Consider a fourth-grade student who, whenasked by his teacher how old the Earth is,replies "Four billion and three years old." (Thestudent had been told by a first-grade teacherthree years earlier that the Earth was fourbillion years old.)

Obviously, we don't know the age of Earth tothe year, so it is not appropriate to report a

number that suggests we do.


37/56

Uncertainty in

Measurements In order to convey the appropriateuncertainty in a reported number, wemust report it to the correct number of

significant figures. The number 83.4 has three digits. All three digits are significant. The 8 and

the 3 are "certain digits" while the 4 is

the "uncertain digit."
http://localhost/var/www/apps/conversion/tmp/scratch_7/CentralScienceLive/Chapter01/CH01_1.5_Main.htmlhttp://localhost/var/www/apps/conversion/tmp/scratch_7/CentralScienceLive/Chapter01/CH01_1.5_Main.htmlhttp://localhost/var/www/apps/conversion/tmp/scratch_7/CentralScienceLive/Chapter01/CH01_1.5_Main.html


38/56

Uncertainty in

Measurements As written, this number impliesuncertainty of plus or minus 0.1, or errorof 1 part in 834.

Thus, measured quantities are generallyreported in such a way that only the lastdigit is uncertain.

All digits, including the uncertain one,

are called significant figures.


39/56

Uncertainty in

MeasurementsGuidelines Nonzero digits are always significant457 cm (3

significant figures); 2.5 g (2 significant figures).

Zeros between nonzero digits are alwayssignificant1005 kg (4 significant figures); 1.03cm (3 significant figures).

Zeros at the beginning of a number are neversignificant; they merely indicate the position of

the decimal point

0.02 g (one significantfigure); 0.0026 cm (2 significant figures).


40/56

Uncertainty in

Measurements Zeros that fall at the end of a number orafter the decimal point are alwayssignificant0.0200 g (3 significant

figures); 3.0 cm (2 significant figures). When a number ends in zeros but

contains no decimal point, the zeros mayor may not be significant130 cm (2 or 3

significant figures); 10,300 g (3, 4, or 5significant figures).


41/56

Uncertainty in

Measurements To avoid ambiguity with regard to the numberof significant figures in a number with tailingzeros but no decimal point, such as 700, we usescientific (or exponential) notation to express

the number. If we are reporting the number 700 to three

significant figures, we can leave it written as itis, or we can express it as 7.00 x 102.

There is no ambiguity in the latter regarding

the number of significant figures, becausezeros after a decimal point are alwayssignificant.


42/56

Uncertainty in

Measurements However, if there really should be onlytwo significant figures, we can expressthis number as 7.0 x 102.

Likewise, if there should be only onesignificant figure, we can write 7 x 102.

Scientific notation is convenient forexpressing the appropriate number of

significant figures.


43/56

Uncertainty in

Measurements It is also useful to report extremelylarge and extremely small numbers.

It would be most inconvenient for us tohave to write all of the zeros in thenumber 1.91 x 10-24

(0.00000000000000000000000191).


44/56

Uncertainty in

Measurements When measured numbers are used in acalculation, the final answer cannot have anygreater certainty than the measured numbersthat went into the calculation.

In other words, the precision of the result islimited by the precision of the measurementsused to obtain that result.

For example: If we measure the length of oneside of a cube and find it to be 1.35 cm; and we

then calculate the volume of the cube using thismeasured length, we get an answer of 2.460375cm3.


45/56

Uncertainty in

Measurements Our original measurement had three significantfigures. The implied uncertainty in 1.35 is 1 partin 135.

If we report the volume of the cube to sevensignificant figures, we are implying anuncertainty of 1 part in over two million! Wecan't do that.

In order to report results of calculations so as

to imply a realistic degree of uncertainty, wemust follow the following rules.


46/56

Uncertainty in

Measurements When multiplying or dividing measurednumbers, the answer must have the samenumber of significant figures as themeasured number with the fewestsignificant figures.

When adding or subtracting, the answercan have only as many places to the rightof the decimal point as the measured

number with the smallest number ofplaces to the right of the decimal point.


47/56

Uncertainty in

Measurements Using these rules, we would report

the volume of the cube in the

example above as 2.46 cm3

. Use the Significant Figures activity

to practice reporting calculated

numbers to the appropriate numberof significant figures.


48/56

Uncertainty in

Measurements

CentralScienceLive\Chapter01\CH01_1.5_Main.html


49/56

Uncertainty in

Measurements Not all numbers are measured numbers. There are some numbers that arise as a

result of counting or as a result of adefinition.

If there are three birds in a cage, thereis no uncertainty in the number of birds.


50/56

Uncertainty in

Measurements Likewise, there is no uncertainty in thenumber of items in a dozen.

These are exactnumbers, and they aretaken to have an infinite number ofsignificant figures (exact numbers shouldnever limit the number of significant

figures you report in a calculatedanswer).


51/56

Dimensional Analysis Solving problems in chemistry requirescareful manipulation of numbers andtheir associated units, a method knownas dimensional analysis.

For example: What is the volume of a5.25-gram sample of a liquid with density1.23 g/mL?

The density of the liquid can be used as a

conversion factor.


52/56

Dimensional Analysis For the liquid in the example, 1.23 gramsare equal to 1 milliliter (1 mL).

When the numerator and denominator of

a fraction are equal, the fraction has avalue of 1, meaning that we can multiplyby it for the purpose of changing units.

The density conversion factor can beexpressed in either of the following two

ways.


53/56

Dimensional Analysis


54/56

Dimensional Analysis The one we choose to multiply by depends onwhat units we want in our result.

In this case we want an answer in units ofmilliliters. So we choose the fraction on theright and multiply it by the mass given in theproblem.

Note that if we had chosen the other version ofthe density conversion factor, we would have

ended up with a different number and alsononsensical units.


55/56

Dimensional Analysis


56/56

Dimensional Analysis This illustrates the importance of carrying unitsthrough a calculation.

One way to check your work is to carefullycancel units to make sure that you arrive at ananswer with the appropriate units.

When you end up with units that don't seem tohave any reasonable physical meaning, such asgrams squared per milliliter, you will realize that

you must have made some sort of mistake. Go back and check your work.

Kimia Dasar Chap.1

Documents

Transcript of Kimia Dasar Chap.1