Lab PreviewDirections: Answer these questions before you begin the Lab.
1. Why is there a warning to not point the bottles at anyone during the lab?
2. What type of solution is a carbonated beverage?
On a hot day, a carbonated beverage will cool you off. If you leave the bever-age uncovered at room temperature, it quickly loses its fizz. However, if youcap the beverage and place it in the refrigerator, it will still have its fizzhours later. In this lab you will explore why this happens.
Real-World QuestionWhat effect does temperature have on the fizz,or carbon dioxide, in your carbonated bever-age?
Goals■ Observe the effect that temperature has on
solubility.■ Compare the amount of carbon dioxide
released at room temperature and in hot tapwater.
Materialscarbonated beverages in plastic bottles,
thoroughly chilled (2) balloons (2)tapefabric tape measure*string*rulerhot tap water*Alternate materials
Safety Precautions WARNING: Do not point the bottles at anyoneat any time during the lab.
Procedure1. Carefully remove the caps from the thor-
oughly chilled plastic bottles one at a time.Create as little agitation as possible.
2. Quickly cover the opening of each bottlewith an uninflated balloon.
3. Use tape to secure and tightly seal the bal-loons to the top of the bottles.
4. Gently agitate one bottle from side to sidefor two minutes. Measure the circumfer-ence of the balloon. Record your observa-tions on the table on the next page.
WARNING: Contents under pressure can causeserious accidents. Be sure to wear safety goggles,and DO NOT point the bottles at anyone.5. Gently agitate the second bottle in the
same manner as in step 4. Then, place thebottle in a container of hot tap water forten minutes. Measure the circumference ofthe balloon.
Lab PreviewDirections: Answer these questions before you begin the Lab.
1. Why is concentrated red cabbage juice considered to be an indicator?
2. In this experiment there are many safety precautions. Explain why you need to be very carefulwhen dealing with acids and bases.
You have learned that certain substances, called indicators, change colorwhen the pH of a solution changes. The juice from red cabbage is a naturalindicator. How do the pH values of various solutions compare to each other?
Real-World QuestionHow can you use red cabbage juice to deter-mine the relative pH of several solutions?
Materialssmall test tubes (9)test-tube rackconcentrated red cabbage juice in a dropper
baking soda solution, soap solution,0.1M hydrochloric acid solution, white vinegar,colorless carbonated soft drink, borax soapsolution, distilled water
grease pencildroppers (9)
Goals■ Determine the relative acidity or basicity of
several common solutions.■ Compare the strengths of several common
acids and bases.
Safety Precautions
WARNING: Many acids and bases are poiso-nous, can damage your eyes, and can burn your
skin. Wear goggles and gloves AT ALL TIMES.Tell your teacher immediately if a substancespills. Wash your hands after you finish butbefore removing your goggles.
Procedure1. Use the data table on the next page to
record the names of solutions to be tested,the colors caused by the added cabbagejuice indicator, and the relative strengths ofthe solutions.
2. Mark each test tube with the identity of theacid or base solution it will contain.
3. Half-fill each test tube with the solution tobe tested. WARNING: If you spill any liquidson your skin, rinse the area immediately withwater. Alert your teacher if any liquid spills inthe work area or on your skin.
4. Add ten drops of the cabbage juice indicatorto each of the solutions to be tested. Gentlyagitate or wiggle each test tube to mix thecabbage juice with the solution.
5. Observe and record the color of each solution in Table 2 in the Data and Observations section.
Use your data to create labels for solutions you tested. Include the relative strength ofeach solution and any other safety information you think is important on each label. Formore help, refer to the Science Skill Handbook.
Determining pH ValuesCabbage Relative StrengthJuice Color of Acid or Base
bright red strong acid
red medium acid
reddish-purple weak acid
purple neutral
blue-green weak base
green medium base
yellow strong base
Conclude and Apply1. Compare your observations with Table 1. Record in Table 2 the relative acid or base strength of
each solution you tested.
2. Classify which solutions were acidic and which were basic.
3. Identify which solution was the weakest acid. The strongest base? The closest to neutral?
4. Predict what ion might be involved in the cleaning process based upon your data for the
ammonia, soap, and borax soap solutions.
5. List the solutions by pH value starting with the most acidic and finishing with the most basic.
Form a HypothesisForm a hypothesis that explains why the borax soap solution was less basic than an ammoniasolution of approximately the same concentration.
If you make a saltwater solution, you can use either table salt or rock salt. As long as the massof each is the same, the salt with the greater surface area—table salt—will dissolve faster. Otherfactors also affect the rate at which a solute dissolves. For example, temperature and stirring willchange the dissolving rate of solute. In addition, the dissolving rates of gases are affected bychanges in pressure.
StrategyYou will explain the effects of particle size,
temperature, and stirring on a solid-liquid solution.
You will explain the effects of temperature,stirring, and pressure on a gas-liquid solution.
Materials 6 cups (transparent plastic)graduated cylinder (100-mL)water (cold)tap water (hot)3 paper towels6 sugar cubeswatch with second handsoda water (bottle)bottle openerbeaker (500 mL)stirring rodWARNING: Use care when handling hot liquids. Do not taste, eat, or drink any materialsused in the lab.
ProcedurePart A—Solid-Liquid Solution1. Label the six plastic cups A through F. Use
the graduated cylinder to add 100 mL ofcold water to each of cups C, D, E, and F.Add 100 mL of hot water from the tap toeach of cups A and B.
2. On three separate paper towels, crush threeof the sugar cubes.
3. Add the crushed sugar and sugar cubes tothe cups (one at a time) as indicated in Table 1. Immediately begin stirring cups Eand F. Observe closely and record the timerequired for the sugar to dissolve completely.See Figure 1. When no sugar particles arevisible, record the time in Table 1.
Part B—Gas-Liquid Solution1. Rinse cups A, B, and C from Part A with
water.2. Observe the unopened bottle of soda
water. Open the bottle and observe it again.Compare your observations and recordyour comparison in Part B of the Data andObservations section.
3. Pour hot water from the tap into the 500-mL beaker until it is about half full.
4. Add 25 mL of soda water to each of thethree cups. Stir the soda water in cup B. SeeFigure 2. Place cup C in the beaker of hotwater. Leave cup A as your control.Compare the rate of bubbling in each cup.Record your observations in Table 2.
6. What factors cause the rate of bubbling in soda water to increase?
7. Carbonated beverages contain dissolved CO2 gas. If you shake the bottle and then open it, thebeverage may shoot into the air. Explain why this happens.
Strategy Check
Can you demonstrate the effect increasing the volume of solvent has on the dissolvingrate of solids in solution?
Can you compare and contrast the effect of temperature on the dissolving rate of solidsin solution by dissolving sugar in hot tea and iced tea?
The most familiar kind of solution is a solid dissolved in water. When you add lemon drinkmix to water, you make lemonade, a water solution. Usually, no chemical change takes place whena solid is dissolved in a liquid. If the liquid evaporates, the original solid remains chemicallyunchanged.
The maximum amount of solute that can dissolve in a fixed amount of solvent is called the solubility of the solution. Solubility is often expressed as grams of solute per 100 grams of solvent.The solubility of a substance is not the same for all conditions. For example, temperature changescan affect the solubility of a solid in water.
StrategyYou will determine the solubility of a salt.You will determine the effect of temperature on the solubility of a salt.You will interpret information from a solubility graph.
Materials 2 beakers (250-mL)hot platethermometerice3 test tubes3 pie tins (aluminum)potassium chloride, KCl(s)graduated cylinder (10-mL)water (distilled)test-tube racktest-tube holdershot mittbalanceWARNING: Wear safety goggles and a laboratory apron throughout this experiment.
Procedure1. Pour tap water into one beaker until it is
about one-third full. Heat the water on thehot plate until the temperature reaches55°C–60°C. Use the thermometer to deter-mine the temperature.
2. Pour ice water into the second beaker untilit is about one-third full.
3. Label the three test tubes A, B, and C. Alsolabel the three aluminum pans A, B, and C.Find the mass of each pan and record it inTable 1.
4. Add 5.0 g of KCl to each test tube.
5. Using the graduated cylinder, add 5.0 mLof distilled water to each test tube. Holdeach tube one-fourth of the way downfrom the top with your thumb and indexfinger. Flick the bottom of the tube withthe index finger of your other hand. In thisway, gently shake each tube for 30 s. Becareful to avoid spilling solution.
6. Place test tube B in the test-tube rack.7. Place test tube A in the beaker of ice water
8. Slowly pour the liquid from tube A intopan A, and from tube B into pan B. Donot transfer any of the solid. You will needto pour the liquid slowly.
9. Carefully place tube C in the water on thehot plate. Allow the contents to reach thetemperature of the water bath, which willtake about 5 min. Use the test-tube holderto remove the tube to the test-tube rack.WARNING: The tube will be hot.
10. Using the test-tube holder, carefully pourthe liquid from tube C into pan C. Do nottransfer any of the solid. You will need topour the liquid slowly. See Figure 1.
11. Determine the mass of each pan and itsliquid. Record the masses in Table 1.
12. Heat the pans on a hot plate using lowheat. When all the liquid evaporates, use athermal mitt to remove the pans from theheat. WARNING: Do not touch the hotpans or the hot plate. After the pans havecooled, find the mass of each and recordthe information in Table 1.
13. Determine the mass of the water evaporated from each pan by subtractingthe mass of the pan after evaporationfrom the mass of the pan and water.
14. Determine the mass of the salt left in eachpan after evaporation by subtracting themass of the empty pan from the mass ofthe pan after evaporation. Record thisinformation in Table 1.
15. Use the masses of the dissolved salts todetermine the solubility per 100 g of water.Use a proportion in your calculations.Record the solubility in Table 1.
Questions and Conclusions1. What type of solid material settled to the bottom of each test tube?
2. What would you expect to happen to the solubility of KCl in each tube if the temperature ofthe water were increased to 75°C?
3. Look at the solubility graph in Figure 2. This graph shows how temperature changes affect thesolubility of four common compounds.a. How does an increase in temperature affect the solubility of NaCl?
b. How does an increase in temperature affect the solubility of KNO3?
Figure 2
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NaCIO3
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KBr
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4. Refer to Figure 2. At what temperature does KNO3 have the same solubility as KBr? What is thesolubility at this temperature?
Strategy Check
Can you demonstrate the increased solubility of a solid in a liquid with temperature?
Can you compare and contrast the amount of solute in saturated and unsaturated solutions?
Directions: Use the following terms to complete the concept map.
solvent heterogeneous homogeneous solute
molecular level substance that dissolves
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OverviewSubstances, Mixtures, and Solubility
Directions: Use terms from the concept map to complete the sentences below.7. A mixture with the same composition throughout is a _____________________.
8. In a salt water solution, the salt is the __________________________________.
9. When you stir cocoa powder into milk, the milk is the _____________________.
6. substance that is present in the
greatest quantity.
Mixtures
substances notmixed evenly
5.4.
3.
made up of a
which is a which is the
which are
1.
which are substancesevenly mixed on a
can be can be
2. ____________or solutions
Name Date Class
20 Substances, Mixtures, and Solubility
Section 1 ■ What is a solution?Section 2 ■ Solubility
Directions: Which of the substances below will form a solution? Explain your answer in the space provided.
Instrucciones: Usa los siguientes términos para completar el mapa de conceptos.
disolvente heterogéneas homogéneas soluto
a nivel molecular sustancia que disuelve
Lectura dirigida para
Dominio del contenido
SinopsisSustancias, mezclas y solubilidad
Instrucciones: Usa los términos del mapa de conceptos para completar las siguientes oraciones.7. Una mezcla con la misma composición por toda su extensión es un(a) ________.
8. En una solución de agua salada, la sal es el _____________________.
9. Al revolver chocolate en polvo en la leche, la leche es el(la) _________________.
6. sustancia que está presente enmayor cantidad
Las mezclas
sustancias que noestán mezcladasuniformemente
5.4.
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que es un(a) que es la
que son
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sustancias que mezcladas uni-formemente en un(a)
pueden ser
2. ____________o soluciones
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24 Sustancias, mezclas y solubilidad
Sección 1 ■ ¿Qué es una solución?Sección 2 ■ Solubilidad
Instrucciones: ¿Cuál de estas sustancias formará una solución? Explica tu respuesta en el espacio asignado.
Directions: Use the clues below to fill in the rows of the word puzzle. When the puzzle is completed correctly,the vertical boxes will spell out a mystery word.
What is a solution?
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1. To clean the shower, you must remove a ______ formed by tap water and soap.
2. Elements and compounds cannot be broken down into simpler substances by an ordinary______ process.
3. A ______ mixture contains two or more substances that are evenly mixed.
4. Substances that can be separated by physical means are known as ______
5. Seawater and carbonated beverages have something in common. They’re both ______.
6. A substance that makes something dissolve is a ______.
7. The substance that dissolves in a solution is the ______.
8. During the process of ______, the gases that make up the solution we breathe are separated.
9. A solid-in-solid solution of two metals is known as a(n) ______.
Directions: Write true in the blank if the statement is true. If the statement is false, replace the italicized wordwith a word or term that makes the statement true. Write this new word in the blank.
1. In the water molecule, electrons are equally shared by hydrogenatoms and oxygen atoms.
2. Solutions for which water is the solvent are called aqueoussolutions.
3. If electrons are shared equally between atoms that compose amolecule, that molecule is said to be polar.
4. Water readily dissolves most polar compounds.
5. Table salt, NaCl, is a molecular compound.
6. In an ionic compound, one or more atoms loses electrons, andone or more atoms gains electrons.
7. In solution, the charged regions of water molecules can pulla(n) ionic compound apart.
8. Chemists say, “Like dissolves like.” This means that dissolutiontends to occur when the solid and the solute are similar innature.
9. Most oils tend to dissolve best in nonpolar solvents.
10. Solubility tells you how fast a solute will dissolve.
Directions: Answer the following questions on the lines provided.11. How is the solubility of a substance usually described?
12. What is an unsaturated solution?
13. How can a solution become supersaturated?
14. What happens if you continue to add solute to a saturated solution?
15. Can pressure affect the solubility of a substance in solution? Explain.
16. How does temperature affect the solubility of a solute in solvent?
A person comes to your door claiming to betaking a water survey in your area. The personasks you to run some tap water into a bottle.He or she then adds a chemical to the water inthe bottle. Soon, a sludgelike residue forms atthe bottom of the bottle.
The person tells you that this test shows yourwater is filled with harmful contaminants. Heor she offers to sell you a device that willremove 99% of the harmful contaminants inyour water. The person implies that you needthis device to protect your family.
1. What would you do in this case? How would you find out if the water really is contaminated?
2. The salesperson added a flocculating agent to the water. What is a flocculating agent and howdoes it work?
3. How might this test be misleading?
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Your water may not have any dangerouscontaminants, but it might be hard. Hardwater is water that contains large amounts ofdissolved minerals. Common minerals in hardwater are compounds of calcium, magnesium,iron, and sulfur. Treated water purchased froma town or city and well water can be hard.
Hard water is not harmful to your health.However, it does have some disadvantages.
It may have a bad taste and an odor. Also, theminerals can settle out and form deposits inpipes, cooking utensils, sinks, and hot-watertanks. Hard water requires more soap anddetergent than soft water and can discolorclothes.
Some cities soften water during the treatment process. Devices for softening watercan also be purchased or rented for home use.
4. Assume that your water is hard. Would you be willing to pay extra for soft water—either froma treatment plant or by buying or renting a water softener? Explain your answer.
Procedure1. Measure a cup of water and pour the water
into the pot.2. Stir in 1 teaspoon of sugar until it is
completely dissolved.3. Repeat step 2 until the sugar stops dissolving.4. Record the number of teaspoons of sugar
you added.5. Put the pot on the hot plate and heat the
solution until it is boiling, then reduce theheat so that the solution is simmering.WARNING: Remember to use the thermalmitt when handling hot objects.
6. Record the amount of time it took for thesolution to begin to boil.
7. Repeat steps 2 through 6 using salt insteadof sugar.
8. Repeat steps 2 through 6 using baking sodainstead of sugar.
Aqueous solutions are all around us. In fact, it would be difficult for you to go anywhere withouthaving them nearby in some form. As you learned in this section, aqueous solutions usually containtwo parts, water and the solute. For this activity, you will be working with an adult to determine thesolubility of different common kitchen items.
Materials measuring cup (liquid) hot platecooking pot timerteaspoon saltsugar baking soda
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Conclude and Apply1. Which ingredient was most soluble in the water at room temperature?
2. Create a graph or table to display your results.
3. Which solution took the longest to boil? Why do you think it took longer?
Svante Arrhenius was a Swedish chemist born in 1859. As a doctoral student, Arrhenius studiedthe capacity of certain solutions to conduct electricity. The solutions he determined could conductelectricity were referred to as electrolytic solutions. He hypothesized that electrolytic compoundsbroke into particles when they dissolved. Arrhenius also proposed a new way of thinking about acidsand bases. He said that acids are compounds containing hydrogen that ionize to yield hydrogen ionsin solution. He also said that bases are compounds that ionize to form hydroxide ions in solution.Therefore, both acids and bases form electrolytic solutions. After presenting his findings as part ofhis dissertation defense, Arrhenius was given the lowest possible passing grade. Finally, however, hiswork was recognized when he won the Nobel Prize for chemistry in 1903.
Materials coated wireknife9-volt battery#43 bulb, or a flashlight lightbulbaluminum foilsmall nonmetallic containerorange juicevinegarwater, distilledmilkmeasuring cup
Procedure1. Cut three pieces of wire into approximately
25–30-cm lengths.2. Trim about 1.5 to 2 cm of the coating off
each end of the wires.3. Attach one end of a wire to the negative
post on the battery.4. Attach one end of another wire to the
positive post on the battery.5. Choose one of the ends and attach it to the
base of the bulb.6. Attach one of the ends of the third wire to
the base of the bulb.
7. Attach 5-sq-cm pieces of aluminum foil tothe ends of each wire that you are going toput into the solution. Attach them by fold-ing them over the exposed parts of thewires.
8. Pour one of the solutions into the non-metallic container.
9. Place the aluminum covered end of the wireattached to the battery into the solution.Place the aluminum covered end of the wireattached to the bulb into the solution.
10. Observe.
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Conclude and ApplyDescribe what happened for each of the solutions and identify them as either electrolytic or nonelectrolytic.
A. ______________—substances that dissolve in water and release positively charged hydrogenions that combine with water molecules to form positively charged hydronium ions
1. Acids taste _____________, conduct ____________________, are corrosive, and
______________ with certain metals.
2. Acids are found in foods such as lemons and oranges that contain ______________ acidand are used in many products such as batteries and plastics.
3. ______________________, formed when carbon dioxide in soil dissolves in water, helpsform caves, stalagmites, and stalactites.
B. ______________—substances that accept hydrogen ions; when dissolved in water, a hydroxideion forms
1. Bases taste _______________, feel _________________, are corrosive, and conduct
____________________.
2. ______________ and cleaning products and ______________ in the human body are basic.
C. ___________ is a measure of how acidic or basic a solution is and relates to the concentration
of hydronium ions and hydroxide ions.
1. The pH scale is not linear; a change of 1 pH unit represents a ________________ change inacid or base strength or weakness.
2. The strength of an acid is related to the number of hydrogen ions it ________________ or
how many _______________________ it produces when dissolved in water.
3. The strength of a base is related to the number of hydrogen ions it can _______________
or the number of _______________________ it produces when dissolved in water.
D. Compounds called ___________________ react with acidic or basic solutions and produce
certain colors depending on the solution’s pH; _______________ paper turns blue whenplaced in a basic solution.
E. _______________________—the interaction between the H+ of an acid and the OH– of a base
to form water and a salt; _________________ can help to neutralize excess acid in the stomach
Part A. Vocabulary ReviewDirections: Match the terms in Column II with the definitions in Column I. Write the letter of the correct term inthe blank at the left.
Column I
1. the term used to describe how much solute dissolves in a given amount of solvent
2. describes a solution that contains a large amount ofsolute per given amount of solvent
3. substance that does the dissolving
4. interaction that occurs between acids and bases in which the properties of each are canceled out by the other
5. substances that produce hydroxide ions when they dissolve in water
6. solutions in which water is the solvent
7. a measure of how acidic or basic solutions are
8. another name for a homogeneous mixture
9. tells you how much solute is present compared to the amount of solvent
10. compounds that react with acidic or basic solutions to produce certain colors
11. describe a solution that contains all of the solute that it can hold under a given set of conditions
12. substance that dissolves into a solution
13. combinations of substances that can be separated by physical processes
14. contains a relatively small amount of solute per given amount of solvent
15. contain hydrogen and produce hydronium ions when they dissolve in water
Part B. Concept ReviewDirections: Determine whether the italicized term makes each statement true or false. If the statement is true, writetrue in the blank. If the statement is false, write in the blank the term that makes the statement true.
1. A solid-solid, solution containing two metals is an acid.
2. Dissolution is the process of forming a solution.
3. Unsaturated solutions have less solute than saturated solutions do.
4. Temperature and pressure can change the neutralization of a solute.
5. The ocean is a solution because it is a homogeneous mixture of saltsand water.
6. A gas dissolves in a liquid most rapidly when under low pressure.
7. Sugar dissolves in water because the positive ends of the sugar molecules are pulled off the solute surface by the negative ends ofthe water molecules.
8. A solid dissolves faster when it is ground because grinding decreasessurface area.
9. Generally the concentration of a liquid dissolved in a liquid can beexpressed as a percentage by mass.
10. Basic solutions feel slippery to the touch.
11. A basic solution usually does react with metal.
12. Because grease is nonpolar, it can dissolve in water.
13. Litmus paper is blue in an acidic solution.
14. A hydronium ion reacts with a hydroxide ion during solute-solventneutralization.
This is a bluntnose sixgill shark, a deepwater species that oftenresides near the ocean floor. There, they sometimes lay in ambush,awaiting prey such as fish, crabs, and octopi. When they move, thesesharks can really stir up the sandy bottom.
1. Describe what you see in this photo. What do you see mixing inthe water?
2. What components of seawater can’t you see?
3. If you had a sample of water containing sand and pebbles, howcould you separate the pebbles from the sand and water? Howcould you separate the sand from the water?
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Have you ever been around a teething baby? Cutting teeth is cer-tainly a painful experience. An old folk remedy suggests rubbing oilof cloves on the baby’s gums. It turns out this successful remedy isbased on scientific insight, for oil of cloves dissolves both in waterand into the tissue surrounding nerves in the gums. Once absorbed,the numbing property of the oil gives everyone a little peace.
1. What occurs when something dissolves?
2. When you add sugar to tea, how can you make the sugar dissolvefaster?
Have you ever wondered how an antacid tablet works? This tablethas been dropped into a solution of hydrochloric acid and water. Thehuman stomach uses hydrochloric acid to digest food, but sometimesthere is too much acid and indigestion results. That’s where theantacid tablet comes in.
1. How many states of matter does the photo show?
2. What do you think this glass looked like five minutes after thisphoto was taken?
3. How do you think the concentration of acid in the glass waschanged by the tablet?
