Investigating Matter 4 - mrjuvonen.weebly.com

The Chemistry of FireworksOn Canada Day, when darkness falls, the skies of many townsand cities across the country come alive with colours and sounds.Flares of red, blue, green, and white are joined by cracks andbangs as fireworks displays mark Canada’s national day ofcelebration (Figure 4.1). Fireworks are an ancient technology,first invented in China over 2000 years ago. Today, fireworks can be seen around the world and their creation is an art formcalled pyrotechnics. Pyrotechnics is a branch of chemistry, thescience that involves understanding and changing matter.

The spectacular sights, sounds, and smells of fireworks comefrom the fusion of chemistry and art. Designers of fireworks usethe knowledge that some substances burn with brilliant colourswhen heated (Figure 4.2). Aluminum metal is used in the kitchenas cooking foil. However, when aluminum is heated by an explosion,the metal burns with a bright white flame. The types of fireworksthat light up the night sky or leave a thick glowing trail of lightoften contain aluminum.

Many substances change colour when heated. The greencolours in fireworks usually come from heated substancescontaining copper. The bright yellow-orange colours are based onsodium, a substance present in table salt. The cracks and bangs offireworks are produced when certain substances heat up and expandrapidly. The rapid expansion makes the sound. The explosions are often so powerful that they can be felt as well as heard.

Here is a summary of what youwill learn in this section:

• Three models of understandingmatter include: Indigenous,ancient Greek, and scientific.

• Matter is composed of particles.The type of particles and theirarrangement in a substancedetermine its properties.

• Scientists classify matter as apure substance or a mixture.

• Scientists further classifymixtures as mechanicalmixtures, suspensions, or solutions.

Investigating Matter

Figure 4.1Fireworks displays,such as this one seenat the FireworksFestival in Saskatoonon Labour Day,combine art andchemistry.

4.1

1214.1 Investigating Matter©P

Figure 4.2 Fireworks are lit with a flame.

04_sk_sci9_se_ch04:Layout 1 3/26/11 2:48 PM 21

122 UNIT B Atoms and Elements©P

B1 Quick Science

When substances are mixed, they may change instate (solid, liquid, or gas) or they may change intodifferent substances with different characteristics.Watch for changes in colour, volume, and state as you complete this activity.

PurposeTo observe changes in matter

Observing Changes in Matter

5. Observe and record as many changes to thesubstances in the bag as you can.

6. Use a second resealable plastic bag. Repeatsteps 1 to 5 but use one scoop of calciumchloride powder for step 2 instead of the sodium hydrogen carbonate powder.

7. Use a third resealable plastic bag. Repeat steps 1 to 5 but, this time, place one scoop ofsodium hydrogen carbonate powder in onecorner of the bag and one scoop of calciumchloride powder in the other corner for step 2.

8. Clean up your work area. Follow your teacher’sinstructions to safely dispose of all materials used.

9. Wash your hands thoroughly.

Questions10. Describe what you observed when you mixed

the bromothymol blue with

(a) sodium hydrogen carbonate powder

(b) calcium chloride powder

(c) both powders

11. Were there any changes to the substances inthis activity? How do you know? State theevidence to support your answer.

Pose New Questions12. What evidence might confirm that a new

substance was formed?

13. What evidence might be different if the quantityof one substance were doubled? tripled?

Procedure1. Use the graduated cylinder to measure 30 mL

of bromothymol blue.

2. Hold open a resealable plastic bag. Place onescoop of sodium hydrogen carbonate powderinto a corner of the bag.

3. Pour the bromothymol blue into the bag.Squeeze out the air, and quickly seal the bag.

4. Mix the contents by squeezing the bag for about 20 seconds. Use your hands to detect any temperature change of the bag over themixing time.

• 50-mL graduatedcylinder

• bromothymol blueindicator solution (a chemical indicatorthat changes from blue to blue-green toyellow as the solutionbecomes acidic)

• three resealable plastic bags

• two scoopulas

• sodium hydrogencarbonate powder(baking soda)

• calcium chloridepowder

Materials & Equipment

04_sk_sci9_se_ch04:Layout 1 3/26/11 2:48 PM Page 122

Understanding MatterEvery culture worldwide has its own ways of understanding the physical world. Some First Nations and Métis peoples use a circle—a sacred Medicine Wheel (or sacred circle)—to help them understand. A Medicine Wheel connects everything in the universe together into one whole. As explainedin the previous unit, this holistic way of understanding is common sense to First Nations and Métis peoples. The MedicineWheel is organized into a pattern of four. For example, there are four directions: east, south, west, and north. There are four seasons: spring, summer, fall, and winter, although in some First Nations cultures, six seasons exist. There are four colours:yellow, red, blue (or black), and white. Details vary depending on the Indigenous nation or community (Figure 4.3).

Many First Nations communities understand the compositionof the physical world in terms of four elements. SaskatchewanFirst Nations, such as the Nakawe–, and the Métis peoplerecognize fire, water, air or wind, and rock as the four elements.For these cultures, the four elements are more than non-livingconstituents that make matter. Fire, water, wind, and rock areSpirits that give and take life.

In the Nakawe– creation story, the four elements arose as the Woman or Mother’s Spirit that gave birth to the physicaluniverse. The fire is the initial Spirit of Mother Earth and is the power of woman Spirit that creates the physical world. Firehelped form the rocks, the second element, and is responsible for the shaping and creation of Mother Earth. Air or wind, thenext element, came from the life forces in the rock. As the rock cooled, fog condensed and formed the last element, water.

Other Views on Nature of MatterMany ancient cultures, including East Indian and Islamic, alsodeveloped elaborate explanations of the nature of matter. Greekphilosophers believed that matter is made from combinations offour simple forms of matter: earth, fire, water, and air, whichGreeks called “elements.” About 440 BCE, the Greek philosopherDemocritus argued that breaking down rock into powder andthen grinding the powder further would reduce it to tiny bits of matter that could not be broken down any more. Hisphilosophical idea was not popular because it contradictedphilosophical authorities at the time.


Origin of “Atom”

The modern term “atom” is derived from the Greekatomos, meaning indivisible.

infoBIT

wind

fire

rock

wat

er

Figure 4.3 This Medicine Wheelshows how some Saskatchewan Cree communities understand what the physical world is made of.First Nations and Métis peoplesbelieve that Spirit flows through these four elements.


A scientific model about the structure of matter did not takeshape until the early 1800s. Scientists began having confidence in a model postulated by John Dalton in England, which assumedthat the smallest bit of matter was an “atom.” Each different kindof matter is composed of a different kind of atom. This generalizedidea about what makes up the physical world took almost 100 yearsbefore it became a common-sense idea for all scientists. Differentmodels describing atoms have evolved over time to explain thestructure of matter, and these will be analyzed in Chapter 5.

Forms of MatterMatter is a general term used to describe all objects in the universe.Scientists define matter as anything that has mass and takes upspace. Mass is a measure of the amount of substance in an object.For example, a brick has more mass than an equal-sized chunk of Styrofoam™. Mass is usually measured in kilograms (kg) or in grams (g). Volume is a measure of how much space an objectoccupies. For example, a volleyball has a volume larger than that of a baseball. Volume is often measured in litres (L) or in millilitres (mL). It is also measured in cubic centimetres (cm3),especially for solid objects. All matter has some volume, even ifthat volume is very small.

Scientists believe that matter in the universe commonly existsin four states: solid, liquid, gas, and plasma. Substances may besolid, liquid, gas, or plasma, or a combination of materials in oneor more states. For example, foam is a mixture of a liquid and agas, or a solid and a gas. Bubbles in a foamy bubble bath are liquidfilms of soap with air trapped inside them. Styrofoam™ is a solidplastic containing trapped air. Lightweight aluminum foam can be made by trapping gas inside melted aluminum and then letting the metal harden (Figure 4.4).


Changes of States of Matter

For a given substance, thestate it is in is related to itstemperature. As a substancegains heat energy, particles in the substance vibrate morequickly and move fartherapart. When the temperaturereaches the melting point, asolid will change into a liquid,and at the boiling point, aliquid will change into a gas. At very high temperatures, theparticles in a gas have beenfound to change into anotherform. Since the particles areno longer the same as those in the gas state, this state of matter is given another name—plasma.

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Figure 4.4 Aluminum foam is acombination of two different materialsin different states, a solid and a gas.

Learning Checkpoint

1. What are two features that are common to all forms of matter?

2. Why do you think people from all cultures want to explain the nature of matter?

3. How does a Medicine Wheel help Indigenous people organize theirunderstanding of the physical world?

Suggested Activities •B2 Inquiry Activity on page 128B3 Quick Science on page 130


Classifying MatterAll matter is made up of different types or combinations ofparticles. For example, gold and iron are both metals, but theyhave very different characteristics. Pure gold is yellow and is sosoft that a fingernail can put a mark on it, whereas iron is greyand much too hard to scratch with a fingernail. These two metalshave different characteristics because the particles that make upeach metal are different. That is, all particles of gold are identical,and all particles of iron are identical, but particles of gold aredifferent from particles of iron.

Different types and combinations of particles give every typeof matter particular characteristics, or properties. A property is a characteristic that describes a substance. Scientists classifymatter as pure substances or mixtures, depending on how their particles are arranged.

Pure SubstancesA pure substance is made up of only one kind of particle. It hasa unique set of properties, such as colour, hardness, boiling point,and melting point. Scientists further classify pure substances aselements or compounds, depending on their composition.

• An element is a pure substance made up of one type ofparticle that cannot be broken down into any simplersubstance by chemical means. For example, gold is a puresubstance that is an element (Figure 4.5). Later in this unit, you will learn how elements are organized into aperiodic table according to their properties.

• A compound is a pure substance that is made from two ormore elements that are chemically combined. For example,sugar is a pure substance that is a compound (Figure 4.6).Water is also a compound containing the elements hydrogen and oxygen.

MixturesA mixture is a combination of pure substances. However, thesubstances in a mixture do not combine chemically as happenswhen a compound forms. Each substance remains in its originalform, although each is not always easy to see distinctly in themixture. There are three main types of mixtures: mechanicalmixtures, suspensions, and solutions.


Examples Help Give a Word Meaning

Authors use examples to help readers really see themeaning of a word in theirminds. If you can picture the example, you can usuallyunderstand the concept oridea. Watch for examples asyou read. They will help youunderstand new terms.

During Reading

Figure 4.5 An ancient gold mask fromPeru in South America. Gold is anelement and a pure substance.

Figure 4.6 White sugar is acompound and a pure substance. All sugar particles are like all othersugar particles. It is a compoundbecause sugar particles are madefrom more than one element (carbon, hydrogen, and oxygen).


matter

heterogeneousmixtures

homogeneousmixtures

solutionssuspensionsmechanicalmixtures

mixtures

elements

pure substances

compounds

each is a combination of puresubstances not chemically combined

each is made up of onlyone type of particle

the different parts in themixture are visible

all parts in the mixturelook the same

each is made up of onlyone type of particle that cannot be

broken down into any simpler substance by chemical means

each is made from two or more elements chemically

combined

the different substances that make up the mixture are

visible

the particles of one substance are held within another in a cloudy

mixture

the different substances that make it up are not individually

visible

is anything that has mass and volume

Figure 4.10 A scientific classification of matter

• In a mechanical mixture, the different substances thatmake up the mixture are visible (Figure 4.7). Soil is anexample of a mechanical mixture. So is a mixture of salt andpepper. A mixture in which the different parts are visible iscalled heterogeneous. The prefix “hetero-” means different.

• In a suspension, the tiny particles of one substance areheld within another to create a cloudy mixture (Figure 4.8).Tomato juice is an example of a suspension. These particlescan be separated out when the mixture is poured throughfilter paper. A suspension is also a heterogeneous mixture.

• In a solution, the different substances that make it up are not individually visible (Figure 4.9). One substance is dissolved in another, creating a homogeneous mixture. The prefix “homo-” means same, and all parts of ahomogeneous mixture look the same. Examples of solutions are sugar dissolved in hot coffee, and acetic acid dissolved in water to make vinegar.

A Summary of Matter ClassificationScientists classify matter as pure substances or mixtures.Mixtures may be further classified as either heterogeneous or homogeneous, depending on their appearance. This issummarized in Figure 4.10.


Figure 4.7 A chocolate chip cookie is a mechanical mixture.

Figure 4.8 A salad vinaigrette is amixture of oil, vinegar, and spices.

Figure 4.9 Tea is a solution of water and the extract of tea leaves that dissolve in the water.


A Practical Use for Mixtures in SaskatchewanSolution mining for potash in Saskatchewan (Figure 4.11)has been taking place for almost fifty years. The termpotash refers to potassium-bearing materials, mainlypotassium chloride (KCl). The world’s first potash solutionmine was established in 1964 at Belle Plaine, near Regina.This type of mining involves the use of water or hot waterto dissolve desired minerals from a geological ore zone.Boreholes are drilled vertically or at an angle into the ore toallow water (or other leaching agents) to enter the deposit.The solution that then forms underground is brought tothe surface through a second borehole and is processed by evaporation, crystallization, and drying. Althoughconventional mining of potash occurs in Saskatchewan,there are a number of benefits of using solution mining.Some of these benefits include a shorter time to production,lower technical risk, and lower environmental impact.Knowing the properties of the minerals allows miningcompanies to develop new mining techniques.


1. Name the four elements believed by theNakawe– people to make up the physicalworld. Which element is responsible forthe shaping and creation of Mother Earth?

2. How do scientists define compounds andelements? Give an example of each.

3. How is a mechanical mixture differentfrom a solution according to the commonscientific classification system?

4. Is a compound, such as water, a puresubstance or a mixture? Explain.

5. What are the four common states of matter that scientists use to describe matter in the universe?

6. Can a sample of matter exist in two statesat one time? Use an example to explainyour answer.

CHECK and REFLECT4.1

7. Classify each of the following as ahomogeneous mixture, a heterogeneousmixture, or a pure substance. Justify youranswer in each case.

8. What are two benefits of solution miningfor potash (material containing mainlypotassium chloride) over conventionalmining of potash in Saskatchewan?

9. Describe three things about forms of matterthat you learned about in this section.

Question 7

Figure 4.11 Mosaic power area supervisor talksabout the solution mining process at the potashmine site in Belle Plaine.

(a) (b)



B2 Inquiry Activity

Changes to matter can result in the formation of gases.There are many different kinds of gas, and we can usetheir properties to help identify them. Three commongases are oxygen, carbon dioxide, and hydrogen.

Initiating and PlanningWhat are the gas tests that can be used to identifyoxygen gas, carbon dioxide gas, and hydrogen gas?

Identifying Gases

SKILLS YOU WILL USE■ Using appropriate equipment

and tools■ Recording and organizing data

CAUTION: Hydrogen peroxide may sting your skin.Potassium iodide will stain skin and clothing. Keep your hair tied back when working near open flames.

• three medicine droppers

• three medium test tubes

• test-tube rack

• 3% hydrogen peroxide solution

• dish soap

• two scoopulas

• potassium iodide powder

• matches

• wooden splints

• 0.1 M acetic acid solution (vinegar)

• sodium hydrogen carbonate powder(baking soda)

• 2 M hydrochloric acid solution

• forceps

• mossy zinc chunks

• large test tube

• test-tube holder


Toolkit 1

Performing and Recording

Part 1 — Preparation of Oxygen1. Using a medicine dropper, add 1 mL (about

20 drops) of hydrogen peroxide solution to aclean test tube.

2. Add two drops of dish soap.

3. Use a scoopula to add a small amount (less than the size of a pea) of potassium iodidepowder to the test tube.

4. Use matches to light a wooden splint.

5. Blow out the flame to make a glowing splint.Insert the glowing splint into the mouth of the test tube (Figure 4.12). Observe and record what happens to the glowing splint.

6. Clean up as directed by your teacher.

Part 2 — Preparation of Carbon Dioxide7. Using a medicine dropper, add 1 mL (about

20 drops) of acetic acid to the second clean test tube.

8. Use the second scoopula to add a small amount(less than the size of a pea) of sodium hydrogencarbonate powder to the test tube.

9. Use matches to light a wooden splint.

Figure 4.12 A glowing splint will reignite in the presence of oxygen.

Key ActivityDI


129Chapter 4 People of all cultures investigate matter according to various properties.©P

B2 Inquiry Activity (continued)

10. Insert the flaming splint into the test tube (Figure 4.13). Observe and record what happensto the splint.

14. Keep holding the large test tube upside down asyou lift it off the small test tube. Use matches tolight a wooden splint.

15. Insert the flaming splint into the large test tube.Observe and record what happens to the splint.

16. Clean up your work area. Follow your teacher’sinstructions to safely dispose of all materialsused. Wash your hands thoroughly.

Analyzing and Interpreting17. Describe what happens in a positive test for

oxygen gas.

18. Describe what happens in a positive test forcarbon dioxide gas.

19. Describe what happens in a positive test forhydrogen gas.

20. Write a procedure for distinguishing betweenoxygen gas and carbon dioxide gas.

Communication and Teamwork21. Explain why the three parts of this activity can be

used to distinguish among oxygen, hydrogen, andcarbon dioxide gas but not to determine whetheran unknown gas is one of these three.

Figure 4.13 A flaming splint will be extinguished in the presence of carbon dioxide.

Figure 4.14 Trapping hydrogen gas

11. Clean up as directed by your teacher.

Part 3 — Preparation of Hydrogen12. Using a medicine dropper, add about 2 mL of

hydrochloric acid to the third clean test tube.

13. Use forceps to add a small piece of mossy zinc to the third test tube. Use a test-tube holder toplace a large test tube upside down and over the smaller test tube in order to trap any gas(Figure 4.14).



B3 Quick Science

You can manipulate matter to change its properties.In this activity, you will mix together different liquidsand a solid to produce a completely differentsubstance: a foam.

PurposeTo produce a new substance, such as a foam, andobserve its characteristics

Foam in a Cup

5. Position the tip of the medicine dropper at thevery bottom of the first beaker, then squeeze the bulb in order to release all the vinegar(Figure 4.15). Record your observations.

• corn syrup

• two 250-mL beakers

• two colours of food colouring

• stirring rod

• teaspoon

• sodium hydrogen carbonate powder (baking soda)

• water

• 50-mL graduated cylinder

• vegetable oil

• white vinegar

• medicine dropper


Procedure1. Pour about 30 mL of corn syrup into a beaker.

Stir in three drops of one food colouring. Use ateaspoon to sprinkle a heaping spoonful (about20 g) of sodium hydrogen carbonate powder on the corn syrup.

2. Pour 30 mL of water into a graduated cylinder.Hold the beaker at a slight angle, and carefullypour the water in down one side. Add 30 mL ofvegetable oil to the beaker in the same way.

3. Into a separate beaker, pour 20 mL of vinegar.Add three drops of the other food colouring.Record your observations.

4. Fill the medicine dropper with coloured vinegarfrom the second beaker.

6. Clean up your work area. Follow your teacher’sinstructions to safely dispose of all materialsused. Wash your hands thoroughly.

Questions7. Write a statement to describe your observations

in step 3.

8. Write a statement to describe your observationsin step 5.

9. What types of changes did you observe?

10. Describe a characteristic of foam that you observed.

11. Describe the state or states of matter of the foamproduced in step 5.

Pose New Questions12. Why did you have to position the tip of the

medicine dropper containing coloured vinegar at the very bottom of the first beaker?

13. What effect do you think simply pouring thecoloured vinegar into the first beaker would have?

Figure 4.15 Adding coloured vinegar to the first beaker


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