Gases Online Assessment
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by Cassy Baker
| 20 Questions
Note from the author:
Summative open note Gas laws, stoichiometry, and Kinetic Molecular theory quiz
Use the kinetic molecular theory to explain the following scenario: You are planning a surprise for Ms. Baker. You plan to leave helium balloons in her room up high where she can not reach them to remove them (it is fun being short). To test your surprise you leave a helium filled Mylar balloon to float over night in Ms. Baker's classroom. When you left the balloon was floating approximately 6 ft above the floor. The next morning after clearing your windshield of frost you drive to school early to check on your surprise and you find that the balloon is sadly floating only 2 ft from the floor. Explain what has happened to your balloon assuming ideal behavior.
In the fermentation process, yeast converts glucose to ethanol and carbon dioxide. What volume of carbon dioxide, measured at 745 torr and 25.0°C, can be produced by the fermentation of 10.0 g of glucose? C6H12O6(aq) ® 2C2H5OH(aq) + 2CO2(g)
Dry air is approximately 78% nitrogen, 21% oxygen and 1% argon, by number of molecules. What is the partial pressure of oxygen in a sample of dry air, if atmospheric pressure is 751 torr?
A 3.60-L gas sample is at a pressure of 95.5 kPa and a temperature of 25.0°C. a. Calculate the volume occupied by the gas at STP, assuming it behaves ideally. b. If the gas sample weighs 6.10 g, calculate the molar mass of the gas.
At very high pressures (~ 1000 atm), the measured pressure exerted by real gases is greater than that predicted by the ideal gas equation. This is mainly because
A such high pressures cannot be accurately measured.
B real gases will condense to form liquids at 1000 atm pressure.
C gas phase collisions prevent molecules from colliding with the walls of the container.
D of attractive intermolecular forces between gas molecules.
E the volume occupied by the gas molecules themselves becomes significant
At moderate pressures (~ 200 atm), the measured pressure exerted by CO2 gas is less than that predicted by the ideal gas equation. This is mainly because
A such high pressures cannot be accurately measured.
B CO2 will condense to a liquid at 200 atm pressure.
C gas phase collisions prevent CO2 molecules from colliding with the walls of the container.
D of attractive intermolecular forces between CO2 molecules.
E the volume occupied by the CO2 molecules themselves becomes significant.
The ideal gas law tends to become inaccurate when
A the pressure is lowered and molecular interactions become significant.
B the pressure is raised and the temperature is lowered.
C the temperature is raised above the temperature of STP.
D large gas samples are involved.
E the volume expands beyond the standard molar volume.
two flasks with equal volumes each contain argon gas. Four students are
discussing whether the density of the gas inside the flasks could be different
A The density could be different if the number of particles in the flasks is different.
B The density could be different if each of the argon particles is more compressed in one of the flasks.
C The densities must be the same because each argon particle has a certain mass and volume.
D The densities must be the same because each flask contains only argon gas.
On a very hot and humid day, Alphonse takes an empty jar off the shelf. He puts a lid on the jar tightly and places it in the refrigerator. One hour later Alphonse discovers that many tiny water drops have formed on the inside of the sealed jar. Choose the best statement
A“The air particles in the jar changed to water particles when cooled. ”
B“Water particles in the form of gas slowed and clump together when cooled."
C “The particles were always there but became much larger and visible when cooled.”
D“Some liquid particles were created during cooling of the jar.”
Untitled Option 5
Jane and Allen are experimenting in the lab with a sealed syringe of air. The syringe of air begins in a hot water bath and then they move it to an ice water bath. The plunger is free to move and it moves in when the syringe is placed in the ice water. [
] What happens to the pressure of the air trapped in the syringe? Compare the pressure of the air in the syringe in hot water to the air pressure in the ice water well after the plunger has stopped moving.
A The pressure stays the same
B The pressure increases
C The pressure decreases
D There is not enough information to answer.
Solid Calcium carbonate decomposes at high temperature to form carbon dioxide gas and calcium oxide solid. How many grams of calcium carbonate are required to form 5.2 L of Carbon dioxide at 1.03 atm and 150 degrees C?
How many liters of water are formed when 3.5 Liters of ethylene (C2H4) react with 2.5 Liters of Oxygen gas at 1.3 atm and 75 degrees C?
remember that the products of a combustion reaction are carbon dioxide and water vapor
Ima Chemist found the density of Freon-11 (CFCl3) to be 5.58 g/L under her experimental conditions. Her measurements showed that the density of an unknown gas was 4.38 g/L under the same conditions. What is the molar mass of the unknown?
A 96.7 g/mol
B 108 g/mol
C 127 g/mol
D 165 g/mol
E 175 g/mol
If 0.750 L of argon at 1.50 atm and 177C and 0.235 L of sulfur dioxide at 95.0 kPa and 63.0C are added to a 1.00-L flask and the flask's temperature is adjusted to 25.0C, what is the resulting pressure in the flask?
A 0.0851 atm
B 0.244 atm
C 0.946 atm
D 1.74 atm
E 1.86 atm
A gas consists of 85.7 % carbon and 14.3% hydrogen, by weight. A sample of this gas weighing 0.673 g occupies 729 mL at a pressure of 720.0 mmHg and a temperature of 77C. Calculate its empirical and molecular formulas.
Combination of empirical formulas and gas laws, Oh my! -- Remember that you need the molecular formulas molar mass to find its molecular formula. Can you find the molar mass of a gas?
A CH, C2H2
B CH2, C2H4
C CH2, C3H6
D CH3, C2H6
E CH4, CH4
Hydrochloric acid is prepared by bubbling hydrogen chloride gas through water. What is the concentration of a solution prepared by dissolving 225 L of HCl(g) at 37°C and 89.6 kPa in 5.25 L of water?
Molarity and Gases! Remember that molarity is Moles per Liter. Can you determine the number of moles of a gas?
A 1.49 M
B 1.66 M
C 7.82 M
D 12.5 M
E 16.6 M
Calculate the pressure of a helium sample at -207.3°C and 768 mL if it exerts a pressure of 175 kPa at 25.0°C and 925 mL.
A 32.1 kPa
B 46.6 kPa
C 657 kPa
D. 953 kPa
E None of these choices is correct since the pressure would have to be negative.
A carbon dioxide sample weighing 44.0 g occupies 32.68 L at 65C and 645 torr. What is its volume at STP?
A 22.4 L
B 31.1 L
C 34.3 L
D 35.2 L
E 47.7 L
A sample of oxygen gas has its absolute temperature halved while the pressure of the gas remained constant. If the initial volume is 400 mL, what is the final volume?
A20 mL
B133 mL
C200 mL
D400 mL
E800 mL
A weather balloon was initially at a pressure of 0.950 atm, and its volume was 35.0 L. The pressure decreased to 0.750 atm, without loss of gas or change in temperature. What was the change in the volume?
Aincreased by 44.3 L
Bincreased by 9.3 L
Cincreased by 7.4 L
Ddecreased by 27.6 L
Edecreased by 7.4 L
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