LAB 9: PROPERTIES OF GASES Part 1: Gas Laws: Diffusion, Volume, Temperature, And Pressure

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1 LAB 9: PROPERTIES OF GASES Part 1: Gas Laws: Diffusion, Volume, Temperature, And Pressure Purpose and Concepts: States of Matter; Vaporization: Practice liquid to vapor conversions in the study of properties of gases. Graham s Law: Illustrate the relationship between the mass of a gas and its rate of diffusion through air and relate to aromas in baking. To predict the relative rate of diffusion of ammonia (NH 3 ) and hydrogen chloride (HCl) gases. Charles Law: Illustrate the relationship between the volume (V), and Temperature (T) of gases. To relate the properties of gases to canning and cooking cream puffs. Boyle s Law: Illustrate the relationship between the pressure (P), and volume (V), of gases and relate to high altitude cooking. Reading: Phases: On Food & Cooking pp Aromas: On Food & Cooking pp ; 387 Cream Puff Pastry, Pate a Choux: On Food & Cooking pp Baking at High Altitudes: On Food & Cooking p. 559 Supplies needed: (*Included in your chemistry kit.) Demo of Graham s Law:: Hot plate Grease pencil Measuring cups Long tubing w/ stoppers Vacuum flasks w/ tubing & stoppers Canning jars Cookie sheet/brownie pan Con NH3 & Con HCl Balloons Metal pans for heating For Cream Puffs: Cotton balls Marshmallows 400 ml food beaker Butter (2 Tbl each grp) Meter stick Sealed capillary tubes Bowl Flour (1/4 c each grp) Colored water w/ syringe Wisk or spoon Egg (1 each) Discussion: Volume, Pressure, and Temperature: Volume, the amount of space taken up by a substance, is described for liquids by the metric units of liters (L), and milliliters (ml), and for solids by the units of cubic centimeters (cm 3 ). The common units of our culture, pints (pts), quarts (pts), and gallons (gal), are rarely used in science. Pressure, the amount of force on an object (or the quantity of collisions with a surface), is measured in atmospheres (atm), millimeters of mercury (mmhg), and Torr. Pressure is measured using a barometer in which a pool of liquid mercury (Hg) is pushed up into a glass vacuum tube by the force of the earth s atmosphere pushing down on it. The height of the mercury in the column is measured in millimeters (mm). One atmosphere of pressure causes the mercury to rise in the vacuum tube to a height of 760 mm or 760 torr (1 atm = 760 mmhg = 760 torr). The culturally common unit of pressure, pounds per square inch (psi) is uncommon in educational science. We will vary the laboratory pressure using either vacuum lines on the bench tops, or aspirator nozzles on the sink faucets. When a stoppered vacuum flask is attached to one of these vacuum sources the number of collisions of gas inside the flask decreases thus decreasing the pressure. Temperature in science is measured using the Celsius ( o C) and Kelvin (K) scales. Celsius and Kelvin degrees measure the same quantity, (a Celsius degree and a Kelvin degree are the same size) they just start at different points, (K = o C + 273). When solving mathematical problems involving temperature, the units must always be in Kelvin. The common temperatures of the daily weather reports in the United States are reported using the Fahrenheit ( o F) scale which is not used in science. The volumes of solids and liquids are only minimally affected by pressure (P) or Temperature (T). Gases, however, behave much differently than solids or liquids in that their Volume (V) significantly expands or contracts with changes in Pressure (P) and Temperature (T). In the laboratory exercises that follow you will discover the relationships between Volume (V), Pressure (P), and Temperature (T) and be able to derive Boyle s Law, Charles Law, and Gay-Lussac s Law of gases for yourself. Direct vs. Inverse Relationships: 1

2 When one property (lets call it property A) influences another property (call it B) to change there are two possibilities for how the change could occur. A direct relationship between properties means that if property A increases (goes up) then property B increases (goes up) also; Or likewise, if A decreases (goes down) then B also decreases (goes down). Properties A and B in a direct relationship are like 2 sides of a barbell. When a weight-lifter raises or lowers the bar both A and B move up or down together. An inverse or indirect relationship between properties means that if property A increases (goes up) then property B decreases (goes down); Or likewise, if A decreases (goes down) then B increases (goes up). Properties A and B in an inverse relationship are like 2 sides of a seesaw. When one side goes down, the other goes up. Of course not every property is related to every other property. Sometimes events are totally unrelated. The scientific method and analysis of experimental testing can help to determine if properties are related or not. A B B A Directly Related Inversely or Indirectly Related Procedures: I. Graham s Law: (Instructor s Demo) MW vs Rate of Diffusion 1. Obtain a 100 cm length of 12 mm diameter dry 8 glass tubing, two cork stoppers to fit the ends, and two cotton plugs. 2. With a dropper place about 10 drops of concentrated hydrochloric acid (12M HCl) 9 to one of the cotton plugs. 3. With a separate dropper, add 10 drops of concentrated ammonium hydroxide (NH 4 OH) 10 to the second cotton plug. 4. With forceps or rubber gloves 9, simultaneously 11 insert the cotton plugs into each end of the glass tubing and stopper the ends. 5. Immediately place the tube on a flat surface and do not disturb it. Record the time. (Box II5) 6. Note the time required for a white ring to appear (Box II6) and mark the ring with a grease pencil Measure and record (II7) the distance between the ring and the nearest edge of each cotton plug. Use these measurements to calculate the relative rate of diffusion 13 and compare to theoretical values. 14 Notes: 8 The tube must be clean and scrupulously dry. Water present will absorb the gases and prevent them from diffusing. HCl NH 3 9 Use extreme caution when dealing with concentrated acids or bases. If you get any on your skin wash immediately with copious amounts (lots) of water. 10 Ammonium hydroxide, NH 4 OH, is a solution of ammonia, NH 3, dissolved in water, H 2 O. Ammonia gas easily escapes the water solution to travel as a gas. 11 You want the gases to start traveling at exactly the same time. This is a race between two gases. We are trying to see if one gas will travel faster than the other gas. 12 The molecules of gas are in constant random motion which enables them to move and occupy any volume available or mix spontaneously with other gases. When HCl and NH 3 meet they will react to form white solid NH 4 Cl according to the equation: HCl (g) + NH 3(g) NH 4 Cl (s) 13 Light molecules (gases of lower molecular mass) have a greater velocity (move faster) than heavier gases. Thomas Graham, in 1829, formulated the following calculation called Graham s law of diffusion: Rate of diffusion gas X = Rate of diffusion gas Y MW gas Y MW gas X 14 To get the theoretical values for the rate of diffusion of NH 3 compared to the rate of diffusion of HCl just insert the molar masses (MW s) into the Graham s law equation. Let s let X be NH 3 (17.0 g/mol) and let Y be HCl (36.5 g/mol). 2

3 Procedures: II. Charles Law: A. Volume vs Temperature 1. Take a glass capillary tube that has been sealed at one end. Using a tiny dropper or syringe with a blunt needle, inject a drop of colored water into the center of the tube so that air is trapped inside the tube. 2. Holding the tube of trapped air near the mouth of the tube. 19 carefully draw a line at the lower edge of the colored water with a marking pencil. 3. Hold the tube at the top, above the marked line, and immerse it in a beaker of ice water. Observe the pocket of trapped air and record your results on the report sheet Now, take the tube out of the ice water and immerse it in a beaker of hot tap water. Observe the pocket of trapped air and record your results on the report sheet. Notes: 19 The tube should be held at near the mouth to avoid warming the trapped air with your hands. If you hold the tube at the bottom then your body temperature is warming the trapped air and may alter your results. 20 Indicate increasing volume (V ) with up arrows, and decreasing volume (V ) with down arrows. Indicate any increase in temperature with up arrows (T ) and decrease in temperature with down arrows (T ). 5. Formulate Charles Law by summarizing your results in the space provided on the report sheet. 6. Dispose of the glass capillary tube in the glass or sharps waste container. Do not put it into the regular garbage cans. B. Charles Law: Practical Application 1: Cream Puffs: Gas Leavening and the Maillard Reaction 1. Preheat oven to 425 o F. 2. Heat together to a rolling boil in a large food beaker ¼ cup (60 mls) water and 1/8 cup (2 Tbl) margarine or butter. 3. Stir in vigorously over low heat until mixture forms a ball. (about 1 minute). ¼ cup all-purpose flour 21 Egg protein in the dough should react with the flour carbohydrates in the cream puff dough to produce a golden brown color (Maillard reaction). We are adding even more protein (from egg or milk) to determine if more protein can make an even darker puff. 22 Frost or dust with powdered sugar if desired. 4. Remove from heat and transfer the flour/butter ball to a mixing bowl. 5. Add and beat until smooth 1 egg 6. Drop dough by spoonfuls about 3 inches apart onto an ungreased cookie sheet. 7. Brush half of your cream puffs with a solution of eggwhite or milk and leave the other half plain. 8. Bake all together at 400 o C until puffed and golden (about minutes). 9. Make note of any color difference between those brushed with milk or eggwhite and those left plain When cool enough to handle.cut off tops and fill puffs with filling of choice (ice cream, pudding, fruit pie filling, yogurt...) 22 3

4 C. Charles Law: Practical Application 2: Canning Food 1. Place a pint Pyrex canning jar or bottle containing about one half inch of water 23 in a pot of boiling water, or in a microwave oven. 2. Heat the jar until steam (gaseous water) steadily comes from the jar. 3. Carefully tighten the lid of the hot jar and set it away from the heat to cool. 24 (Go on with other parts of the lab as this will take a while.) 4. Observe the effects of cooling on the gases in the jar. Record your observations of both heating and cooling on the report sheet. III. Pressure (Vacuum): 1. Attach the benchtop vacuum source 25 to the side arm of a 250 ml vacuum flask using heavy walled tubing Place the palm of your hand over the top of the vacuum flask and then turn on the vacuum line or aspirator water full force. Observe the effect of the vacuum on your hand. 3. Complete the drawing on the report sheet by adding your hand and the vacuum line. Indicate on the inside and outside of the flask drawing the locations of high pressure (P ) with up arrows, and locations of low pressure (P ) with down arrows. IV. Boyle s Law: Volume vs Pressure 4. Slightly inflate a small balloon just large enough so that it can be placed inside your 250 ml vacuum flask. Knot it tightly, and insert the balloon into the vacuum flask. Cap the flask tightly with a rubber stopper. 5. Turn on your vacuum source full force. On the report sheet record your observations. 6. Detach the vacuum tubing 27 to let atmospheric pressure into the vacuum flask. Record your observations. 7. Repeat steps 1-3, but instead of a balloon place a marshmallow inside the flask. Report your results. Notes: 23 If you were really canning then your jar would contain food stuffs and water solution with about a ½ inch air space at the top. A jar that full would take longer to heat than the time allotted in lab so we use a jar with only a little water just to illustrate the process in a shorter time. 24 It is best to leave the hot jar at room temperature to allow it to cool slowly rather than cooling fast with cold water or ice. If a hot jar cools too suddenly the glass may break. 25 If using a sink aspirator do not attach the vacuum tube to the spout that gives water. When the water is turned on no water should enter the vacuum flask. 26 If you use regular strength rubber tubing instead of the heavy walled vacuum tubing your tube will go flat under reduced pressure (vacuum). 27 If you are using the benchtop vacuum lines you may turn the vacuum off before detaching the tubing from the flask. If you are using the sink aspirators then do not turn off the aspirator water until you have removed the tubing to release the vacuum. If low pressure (vacuum) were to exist in the flask at the time that the water is turned off then water will get pulled from the sink back into the flask.. 8. Formulate Boyle s law by summarizing your results in the blanks given on the report sheet. 4

5 Purpose and Concepts: LAB 9: PROPERTIES OF GASES Part 2: Gas Laws: Solubility; Root Beer States of Matter; Sublimation: Use dry ice to illustrate sublimation of a solid to a vapor. Solubility of Gases: Henry s Law; Observe the solubility of gases in water with varying pressures. Observe the solubility of gases in water with varying temperature. Make root beer to illustrate the solubility of gases related to temperature and pressure. Reading: Phases: On Food & Cooking pp Flavor Chemicals in Root Beer/Sassafras: On Food & Cooking p. 259, 409 Supplies needed: (*Included in your chemistry kit.) * flasks, beakers, or cups Vacuum flask w/ stopper & tubing For Root Beer *graduated cylinder Carbonated beverage ml plastic bottle w/ screw cap *Gram kitchen scale Funnel 25g Sugar *Thermometer Cloth kitchen towel 4 ml Root beer extract Microwave or hotplate Small paper cups (Dixie bathroom size) ~20 g Dry ice (crushed in a towel with a hammer ) Discussion: Sublimation occurs when a solid converts to a vapor (gaseous state) directly without becoming a liquid first. Solid water (ice) will sublime when the temperature and pressure are just right. Solid carbon dioxide (dry ice) easily sublimes at room temperature and normal atmospheric pressure. Solubility of Gases: Gases generally have low solubility in water because a gas wants to expand to fill all the space provided rather than to be constrained within a liquid. We can force a gas to dissolve by increasing the pressure. When solid carbon dioxide sublimes into a gas it increases in volume and so in a closed container will increase the pressure. When the pressure increases this forces gaseous CO 2 to enter the liquid water and make a carbonated solution. PROCEDURES: ACTIONS: I. Solubility of Gases: A. Henry s Law: Solubility of CO 2 vs Pressure 1. Pour ice cold 10 carbonated water (CO 2 dissolved in H 2 O) into a vacuum flask to a level of about 1 inch. 2. Connect the flask to the vacuum source and turn it on full force. And observe any bubbles formed; an indication of the change in the solubility of CO 2 in water. Record your observations Detach the vacuum tubing from the source to allow the flask to return to atmospheric pressure. Record your observations.. 4. Formulate Henry s Law by summarizing your results on the report sheet. Notes: 1 Indicate increasing solubility (Ability of gas to dissolve) (S ) of CO 2 gas with up arrows, and decreasing solubility (S ) of CO 2 gas with down arrows. ) 5

6 PROCEDURES: B. Solubility of CO 2 vs Temperature 1. Obtain 2 Erlenmeyer flasks, beakers, or cups of equal size. 2. Into one of the flasks pour carbonated water (CO 2 dissolved in H 2 O) to a level of about 1 inch. 3. Into the second flask put an equal volume of tap water and a thermometer. 4. Place the two flasks side by side on a hot plate and heat but do not boil. (Do not let the tap water approach 100 o C). 5. Observe any bubbles formed; (an indication of change in the solubility of carbon dioxide in water) and record the results 14 NOTES: 2 To tare the beaker means to set the mass of the beaker to zero. This way when you add materials to the beaker you can read the mass of materials added directly. If you do not tare the beaker then you would have to subtract the mass of the beaker from the total mass in order to determine the mass of materials inside. 3 Sucrose = table sugar. 4 Root Beer Extract = solution of caramel color, corn syrup, wild cherry bark extractives, methyl salicylate, vanillin, etc. C. Solubility of CO 2 : Practical Application; Root Beer: 1. To have ingredients ready when needed measure out the following in separate containers and set aside to add when directed. Place a 150 ml beaker on your balance and tare 2 it. Add to the beaker 25g of granulated sucrose. 3 Measure 4 ml of root beer extract 4 (measure into a graduated cylinder then set aside until needed) Place a 400 ml beaker on your balance and tare 2 it. Add to the beaker crushed solid carbon dioxide (CO 2 ). 5 (about g) 6 2. Obtain a small (250 or 355 ml is OK) plastic bottle with screw on lid. 3. Add to the bottle 25 g granulated sucrose 3, (use a funnel to avoid spilling) 2 ml Root Beer Extract Add to the bottle about mls water (It doesn t have to be exact. You can add more later if the root beer is too concentrated.) 5. Cap and shake to mix until the sucrose is dissolved in the water. 6. To the solution spoon in between 3 and 4 grams of solid CO 2. Quickly replace the cap tightly, wrap the bottle in a cloth towel and shake vigorously. 8 5 Solid carbon dioxide = CO 2 = dry ice. 6 You don t have to have exactly grams. The amount of gas preferred in a soda is a matter of taste but usually the more the better. 7 This allows enough room in the bottle to added dry ice and still have room to mix. 8 You should feel the plastic bottle getting rigid with the increased pressure from the gas transitioning from a solid (relatively low volume) to a gas (relatively high volume). (Note that 1 lb of CO 2 solid would fill about 64 gallons of volume or 243 L!) 9 Pour a small sample into a paper cup to taste to determine the desired amount of carbonation. 7. After a few (3-4) minutes of shaking, open the lid carefully to allow any extra gas to escape and add another several grams of CO 2. Cap and shake as before. 8. Continue adding additions of CO 2 (2-3 grams at a time) until the desired mouth feel of carbonation has been reached Describe your root beer including the taste, temperature, and texture. 6

7 Purpose and Concepts: LAB 9: PROPERTIES OF GASES Part 3: Carbon Dioxide: Density and Flammability States of Matter; Sublimation: Use dry ice to illustrate sublimation of a solid to a vapor. Properties of Carbon Dioxide: Illustrate the density of carbon dioxide compared to air. Observe the ability of carbon dioxide to put out fire. Reading: Phases: On Food & Cooking pp Supplies needed: (*Included in your chemistry kit.) *400 ml beaker Small birthday candle Zip lock baggie *Gram kitchen scale Cardboard or card stock paper *graduated cylinder Dry Ice Sodium bicarbonate Matches Gloves& hammer for dry ice Vinegar Discussion: Sublimation occurs when a solid converts to a vapor (gaseous state) directly without becoming a liquid first. Solid water (ice) will sublime when the temperature and pressure are just right. Solid carbon dioxide (dry ice) easily sublimes at room temperature and normal atmospheric pressure. 7

8 PROCEDURES: ACTIONS: I. Carbon Dioxide: A. Preparation and Flammability of Carbon Dioxide (CO 2 ): 1. Make a candle holder by cutting a small X (about 1 cm slits) in the center of a 5 cm 2 (2 in 2 ) piece of heavy card stock paper. 1 NOTES: 1 Or make a small hole in the center of a 5 cm 2 piece of corrugated cardboard. 2 Make sure the candle stands upright in the beaker. 2. Insert a birthday candle into the paper holder and place it in the bottom of a 250 or 400 ml beaker so that the candle stands upright Cover the bottom of the beaker (over the card if needed) with about 3 10 g (1 tablespoon) of baking soda (sodium bicarbonate, NaHCO 3 ). 4. Obtain about 3 20 ml of vinegar (5% acetic acid, HC 2 H 3 O 2 ). 5. Light the candle Slowly pour the vinegar down the inside edge of the beaker being careful not to pour it on the candle. Observe and record the effect of any reaction and write the chemical equation for this reaction. 7. Observe and record the effect of the resulting gas 5 on the flame. If the candle goes out, try to relight it 4. Record your observations. B. Sublimation and Relative Density of CO 2 : Practical Application: Fire Extinguisher 1. Using tongs or insulated gloves 6, place a small piece (about the size of a large marshmallow) of solid carbon dioxide (dry ice 7 ) in a quart size zip-close plastic bag. 2. Flatten the bag to remove as much air as possible and seal the bag shut. 3. Allow the dry ice to slowly warm up to room temperature. Observe and record your observations. 4. Insert the birthday candle and holder made in Part VA into the bottom of a clean 250 or 400 ml beaker. Light the candle Carefully hold your bag of sublimed dry ice over the burning candle and pour the gas onto the flame. Observe and record your observations making note of the density of carbon dioxide gas compared to the density of air (a mixture of mostly nitrogen gas and oxygen gas). 8 3 It is not necessary to accurately measure the quantity as this is a qualitative not a quantitative procedure. 4 It may be necessary to hold a lighted match with tongs to light the candle inside the beaker. 5 Baking soda and acids (such as vinegar) react to make carbon dioxide gas according to the following equation: NaHCO 3(s) + HC 2 H 3 O 2(aq) NaC 2 H 3 O 2(aq) + H 2 O (l) + CO 2(g) Carbon dioxide gas can extinguish a fire by displacing the oxygen in the air around the burning object. When oxygen is removed the fire goes out. 6 Don t touch dry ice with your bare skin; the extreme cold can cause serious skin damage. 1 For fun you may also choose to put a chunk of dry ice into a latex rubber glove or a balloon. Evacuate the air and tie a knot to keep closed. 7 Although carbon dioxide is a gas at room temperature, it is a solid below o C ( o F). Solid carbon dioxide is called dry ice since it changes from solid to gas without forming a liquid in a process called sublimation. 8 Optional: While there is still CO 2 in your beaker try blowing soap bubbles into the beaker and see if they drop to the bottom or float. Soap bubbles may appear to float but really they are resting on top of the carbon dioxide gas. 8

9 Lab 9: Properties of Gases Part 1: Gas Laws Report: I. Graham s Law: MW vs Rate of Diffusion Prediction: Molar Mass (MW) of HCl (g) and NH 3(g) MW of NH 3(g) Name Partner Date MW of HCl (g) Prediction: Who should travel faster? Why? Results: Race between HCl (g) and NH 3(g) Distance traveled (to nearest 0.1 cm) Experimental value of cm traveled by NH 3 cm traveled by HCl = rate of diffusion of NH 3 rate of diffusion of HCl Observations: What did you see? How is distance determined? By NH 3(g) Show calculations: By HCl (g) Theoretically Ammonia (NH 3 ) gas should travel about 1.5 times farther than Hydrochloric acid vapors (HCl) in the same amount of time (or 1.5 times faster). How do your experimental results compare to this? Explanation and Analysis: Was your prediction correct? Explain any anomalies or issues with the experiment. Application: You are standing in the middle of a room. In one corner of the room someone is cutting up apples that give off aromas made of volatile 6-carbon alcohols & aldehydes. In the opposite corner of the room someone is cutting a melon which gives off aromas made of volatile 9-carbon alcohols & aldehydes. 1. If both persons start cutting their fruits at the same time which will you smell first? A. apples B. melon C. both at the same time Explain your answer: 9

10 II. Charles Law: A. Volume vs Temperature Action Observations Effect on Temperature Trapped air immersed in ice water. T or T Effect on Volume V or V Trapped air immersed in hot water. Formulate Charles Law by summarizing your results Explanation & Analysis Explain any anomalies or issues with the experiment. Conclusion Summary: 1. The volume of a gas as the temperature. A. decreases, increases B. increases, increases. C. does not change, changes 2. Charles Law: The volume of a gas the temperature. A. varies directly with B. varies inversely with C. is unrelated to B. Practical Application 1: Cream Puffs Action Observations Effect on Temperature Cream Puff batter Before heating T or T Effect on Volume V or V Cream Puff batter After heating Summarize from your results the chemistry of the rising of cream puffs relating to Charles Law: Explanation & Analysis Summarize any differences between the cream puffs brushed with milk/egg protein and those left plain. Explain any anomalies or issues with the experiment. What should have happened? 10

11 Charles Law Continued The Chemistry of a Cream Puff: Using your own words explain the science happening in the making of a cream puff. (Remember 1) gas laws, and 2) gluten proteins, 3) Maillard reactions, and any other applicable chemistry.) C. Practical Application 2: Canning Action Observations Effect on Temperature Water vapor heated in canning jar T or T Effect on Volume V or V Trapped water vapor cooling in canning jar Summarize from your results the chemistry of canning relating to Charles Law: Explanation & Analysis Explain any anomalies or issues with the experiment. 11

12 III. Vacuum: (circle one) P or P Inside (circle one) P or P Outside IV. Boyle s Law: Volume vs Pressure Action Observations Effect on Pressure a. Vacuum source turned on with balloon in flask. P or P Effect on Volume V or V b. Vacuum hose detached (Vacuum source off) with balloon in flask. c. Vacuum source turned on with marshmallow in flask. d. Vacuum hose detached with marshmallow in flask. Formulate Boyle s Law by summarizing your results Explanation & Analysis Explain any anomalies or issues with the experiment. Conclusion/Summary: 1. The volume of a gas as the pressure. A. decreases, increases B. increases, increases. C. does not change, changes 2. Boyle s Law: The volume of a gas the pressure. A. varies directly with B. varies inversely with C. is unrelated to 12

13 Lab 9: Properties of Gases Part 2: Solubility Report: I. Solubility of Gases: A. Henry s Law: Solubility vs Pressure Action Observations Effect on Pressure a. Vacuum source turned on with carbonated solution in flask. b. Vacuum hose detached with carbonated solution in flask. c. A carbonated beverage is opened on a mountain d. A carbonated beverage is opened below sea level Imagine what you would see. Imagine what you would see. Name Partner Date P or P e. Conclusion: 1. The solubility of a gas in water (the ability of a gas to dissolve) as the pressure. A. decreases, increases B. increases, increases. C. does not change, changes 2. Henry s Law: The solubility of a gas the pressure. A. varies directly with B. varies inversely with C. is unrelated to Explanation/Analysis: Were your results as expected? Explain specifics. Explain anomalies. Effect on gas Solubility S or S B. Solubility vs Temperature Action Observations Effect on Temperature T or T a. Carbonated water at cold temperature b. Tap water at cold temperature c. Carbonated beverage warmed d. Tap water warmed Effect on gas Solubility S or S e. Conclusion: 3. The solubility of a gas in water (the ability of a gas to dissolve) as the temperature. A. decreases, increases B. increases, increases. C. does not change, changes 4. The solubility of a gas the temperature. A. varies directly with B. varies inversely with C. is unrelated to Explanation/Analysis: Were your results as expected? Explain specifics. Explain anomalies. 13

14 Lab 9: Gases Related Questions: Part 1 and Parts 2A & 2B 1. Vocabulary: Match the following words with the term that best describes them: Granulated Sugar Sublimation Solubility Pressure A. The ability of a substance to dissolve. B. The force of molecular collisions on a container. C. The change of a solid state directly into a gaseous state without becoming liquid. D. Sucrose 2. A. Which gas will diffuse faster: (Circle one) Methane (CH 4 ) or Helium (He)? B. Which gas will diffuse faster: (Circle one) Ammonia (NH 3 ) or Hydrogen Sulfide (rotten egg smell; H 2 S)? 3. A. List 2 factors that influence the solubility of a gas in a liquid? B. Describe how each of these affect the solubility of a gas in a liquid. Factor affecting Solubility of Gas in water Description of that effect 4. Water from the tap that has been boiled and then cooled again tastes flat compared to regular tap water at the same temperature that has never been boiled. Explain why. 5. Fish breathe the oxygen gas that is dissolved in water. A. What happens to the amount of dissolved oxygen in a stream that gets too warm? B. What happens to the fish and why? II. Which of the following gas laws best applies to each situation listed below? B. Boyle s Law C. Charles s Law G. Graham s Law H. Henry s Law L. Gay-Lusac s Law T. Solubility vs Temperature N. None of these A balloon bursts at high altitudes. A cake rises when it is baked. The shampoo bottle in your suitcase breaks open on an airplane flight. The aroma of baking bread travels through a home. Food can be cooked faster using a pressure cooker. Tennis balls in Denver, CO are filled with less air than tennis balls in Oregon. Aerosol spray cans should be stored in a cool place. Two containers, one filled with chlorine and the other filled with hydrogen sulfide (H 2 S), simultaneously develop leaks. The odor of hydrogen sulfide is detected before the odor of chlorine. Rapid ascent in an unpressurized airplane may cause intestinal cramps. Gas is evolved when the cap is removed from a cola drink. Cake batter overflows the pan when baked on a mountain but not at sea level. A carbonated beverage spews more when opened on a mountain than when opened in a submarine. Warm pop tastes flat. 14

15 Lab 9: Properties of Gases Part 2 Continued: Solubility Report: Name Partner Date C. Solubility of Gases Cont.: Practical Application: Root Beer Observations & Quality of Product: Describe the properties of your resulting Root Beer. (For example: appearance, flavor, carbonation, temperature, etc..) Analysis: Critique the experiment. What worked well and what might be improved? For example be specific about what ways you might change the procedures in order to make better Root Beer. Part 3 Properties of CO 2 Report I. Carbon Dioxide: Flammability Action a. Vinegar (HC 2 H 3 O 2 ) mixed with Baking Soda (NaHCO 3 ) effect on candle b. Effect of CO 2 on flame Observations/Results c. Attempt to relight flame. d. Chemical Equation for CO 2 production from vinegar & baking soda HC 2 H 3 O 2 + NaHCO 3 Action e. Dry Ice warmed to room temperature (sublimation) Observations/Results f. Effect of CO 2 poured onto a flame Conclusion: Properties of CO 2 Color/Odor Effect of CO 2 on Fires Density Check one: lighter than air heavier than air the same density as air What conclusions can you make about the volume of gaseous carbon dioxide gas compared to solid carbon dioxide? In your own words describe what happens on a molecular level when solid carbon dioxide becomes a gas. (Sublimes) 15