Gas Law exam Qs

0.A gas has a density, at STP, of 3.48 g L−1The most reasonable formula for this compound is (A) C2H6 (B) C6H6 (C) CCl4 (D) CaF2

B

A gas sample with a mass of 10 grams occupies 5.0 liters and exerts a pressure of 2.0 atm at a temperature of 26°C. Which of the following expressions is equal to the molecular mass of the gas? The gas constant, R, is 0.08 (L×atm)/(mol×K). (A) (0.08)(299) g/mol (B) g/mol (C)299/0.08 g/mol (D) (2.0)(0.08) g/moL

A

1.Assuming all other factors remain constant, which of the following changes will NOT affect the total pressure of a gas in a container? (A) Half of the molecules are replaced by an equal number of molecules of a gas with a different molar mass. (B) The average velocity of the molecules is lowered. (C) The frequency of collisions of molecules with the walls is increased. (D) The temperature of the sample is altered.

A

2.A gas mixture contains twice as many moles of O2 as N2 Addition of 0.200 mol of argon to this mixture increases the pressure from 0.800 atm to 1.10 atm. How many moles of O2 are in the mixture? (A) 0.355 mol O2 (B) 0.178 mol O2 (C) 0.533 mol O2 (D) 0.200 mol O2

A

2SO2 (g) + O2 (g) → 2SO3 (g) 4.0 mol of gaseous SO2 and 6.0 mol of O2 gas are allowed to react in a sealed container. At a given point in the reaction, all three gases are present at the same temperature. Which gas molecules will have the highest velocity and why? (A) The O2 molecules, because they have the least mass (B) The O2 molecules, because they are the smallest (C) The SO3 molecules, because they are products in the reaction (D) Molecules of all three gases will have the same speed because they have the same temperature.

A

5.A gas will behave more like an ideal gas if we have an _________and an__________. (A) increased volume, increased temperature (B) increased temperature, increased average kinetic energy (C) increased average kinetic energy, increased pressure (D) increased effusion rate, increased pressure

A

6.The measured pressure exerted by CO2 gas is less than that predicted by the ideal gas equation when at moderate pressures (5 atm at 298 K). This is mainly because (A) the attractive intermolecular forces between CO2 molecules is now a factor (B) CO2 condenses to a liquid at pressures greater than 5 atm at 298 K (C) the volume of the CO2 molecules becomes significant at high pressures (D) the gas phase collisions prevent the CO2 molecules from colliding with the walls of the container

A

7. Under which conditions will a real gas behave most like an ideal gas? (A) Low pressure and high temperature (B) Low pressure and low temperature (C) Low volume and high temperature (D) High pressure and high temperature

A

A 22.0 gram sample of an unknown gas occupies 11.2 liters at standard temperature and pressure. Which of the following could be the identity of the gas? (A) CO2 (B) SO3 (C) O2 (D) He

A

A 255 mL round-bottom flask is weighed and found to have a mass of 114.85 g. A few milliliters of an easily vaporized liquid are added to the flask and the flask is immersed in a boiling water bath. All of the liquid vaporizes at the boiling temperature of water, filling the flask with vapor. When all of the liquid has vaporized, the flask is removed from the bath, cooled, dried, and reweighed. The new mass of the flask and the condensed vapor is 115.23 g. Which of the following compounds could the liquid be? (Assume the ambient pressure is 1 atm.) A) C2H5OH B) C4H10 C) C2H6 D) C4H9OH E) C3H7OH

A

A sample of oxygen gas was found to effuse at a rate equal to two times that of an unknown gas. The the molecular weight of the unknown gas is __________ g/mol. A) 128 B) 8.0 C) 8 D) 16 E) 64

A

How many moles of Na2SO4 must be added to 500 milliliters of water to create a solution that has a 2-molar concentration of the Na + ion? (Assume the volume of the solution does not change). (A) 0.5 mol (B) 1 mol (C) 2 mol (D) 5 mo

A

The Mond process produces pure nickel metal via the thermal decomposition of nickel tetracarbonyl: Ni(CO)4 (l) ¬ Ni (s) + 4CO (g). What volume (L) of CO is formed from the complete decomposition of 444 g of Ni(CO)4 at 752 torr and 22eC? A) 255 B) 20.2 C) 63.7 D) 11.0 E) 0.356

A

The volume of a sample of gas (2.49 g) was 752 mL at 1.98 atm and 62eC. The gas is __________. A) NO2 B) SO3 C) SO2 D) Ne E) NH3

A

What volume of hydrogen gas, at STP, will a 0.100-g sample of magnesium (molar mass = 24.31) produce when reacted with an excess of HCl? Mg + 2HCl → MgCl2 + H2 (A) 92.1 mL (B) 46.1 mL (C) 184 mL (D) 9.2 mL

A

0.At 30°C a sample of hydrogen is collected over water [PH2O= 31.82 mm Hg at 30°C] in a 500-mL flask. The total pressure in the collection flask is 745 mm Hg. What will be the percent of error in the amount of hydrogen reported if the correction for the vapor pressure of water is not made? (A) 0.0% (B) +4.5% (C) −4.5% (D) +4.3%

B

1.What will the total pressure be in a 2.50-L flask at 25°C if it contains 0.016 mol of CO2 and 0.035 mol of CH4? (A) 31.4 mm Hg (B) 380 mm Hg (C) 0.041 mm Hg (D) 935 mm Hg

B

2.The carbon dioxide from the combustion of 1.50 g of C2H6 is collected over water at 25°C. The pressure of CO2 in the collection flask is 746 mm Hg, and the volume is 2.00 L. How much of the CO2 formed apparently dissolved in the water of the pneumatic trough? (A) 0.0814 mol (B) 0.86 g (C) 1.79 g (D) 0.100 mol

B

2SO2 (g) + O2 (g) → 2SO3 (g) 4.0 mol of gaseous SO2 and 6.0 mol of O2 gas are allowed to react in a sealed container. If the temperature remains constant, what percentage of the original pressure will the final pressure in the container be equal to? (A) 67% (B) 80% (C) 100% (D) 133%

B

3. The kinetic molecular theory postulates a direct relationship between (A) increased volume and increased average kinetic energy (B) increased temperature and increased average kinetic energy (C) increased average kinetic energy and increased pressure (D) increased effusion rate and increased pressure

B

An evacuated rigid container is filled with exactly 2.00 g of hydrogen and 10.00 g of neon. The temperature of the gases is held at 0°C and the pressure inside the container is a constant 1.0 atm. What is the mole fraction of neon in the container? (A) 0.17 (B) 0.33 (C) 0.67 (D) 0.83

B

At 333 K, which of the pairs of gases below would have the most nearly identical rates of effusion? A) CO and CO2 B) CO and N2 C) NO2 and N2O4 D) N2O and NO2 E) N2 and O2

B

SO2 (5.0 g) and CO2 (5.0 g) are placed in a 750 mL container at 50eC. The partial pressure of SO2 in the container was __________ atm. A) 1.60 B) 2.76 C) 4.02 D) 0.192 E) 6.78

B

The density of N2O at 1.53 atm and 45.2eC is __________ g/L. A) 0.388 B) 2.58 C) 9.99 D) 1.76 E) 18.2

B

2SO2 (g) + O2 (g) → 2SO3 (g) 4.0 mol of gaseous SO2 and 6.0 mol of O2 gas are allowed to react in a sealed container. Under which of the following conditions would the gases in the container most deviate from ideal conditions and why? (A) Low pressures, because the gas molecules would be spread far apart (B) High pressures, because the gas molecules will be colliding frequently (C) Low temperatures, because the intermolecular forces between the gas molecules would increase (D) High temperatures, because the gas molecules are moving too fast to interact with each other

C

7.How many moles of helium are needed to fill a balloon that has a volume of 6.45 L and a pressure of 800 mm Hg at a room temperature of 24°C? Assume ideal gas behavior. (A) 0.288 (B) 214 (C) 0.278 (D) 2.65 × 10^3

C

A mixture of helium and neon gases has a total pressure of 1.2 atm. If the mixture contains twice as many moles of helium as neon, what is the partial pressure due to neon? (A) 0.2 atm (B) 0.3 atm (C) 0.4 atm (D) 0.8 atm

C

A sample of a gas (5.0 mol) at 1.0 atm is expanded at constant temperature from 10 L to 15 L. The final pressure is __________ atm. A) 1.5 B) 15 C) 0.67 D) 3.3 E) 7.5

C

An evacuated rigid container is filled with exactly 2.00 g of hydrogen and 10.00 g of neon. The temperature of the gases is held at 0°C and the pressure inside the container is a constant 1.0 atm.What is the volume of the container? (A) 11.2 L (B) 22.4 L (C) 33.5 L (D) 48.8 L

C

Arrange the following gases in order of increasing average molecular speed at 25eC. Cl2, O2, F2, N2 A) Cl2 < O2 < F2 < N2 B) N2 < F2 < Cl2 < O2 C) Cl2 < F2 < O2 < N2 D) F2 < O2 < N2 < Cl2 E) Cl2 < F2 < N2 < O2

C

2.If methane, CH4, rather than ethane, CH3CH3 is the gas used under comparable conditions, there will be an increase in (A) volume and average kinetic energy (B) temperature (C) average kinetic energy and pressure (D) effusion rate

D

3.A gas in a 1.50-L container has a pressure of 245 mm Hg. When the gas is transferred completely to a 350. mL container at the same temperature, the pressure will be (A) 1.05 mm Hg (B) 1.05 atm (C) 2.14 mm Hg (D) 1050 mm Hg

D

4.At STP a 5.00-L flask filled with air has a mass of 543.251 g. The air in the flask is replaced with another gas, and the mass of the flask is then determined to be 566.107 g. The density of air is 1.290 g L^-1 What is the gas that replaced the air? (A) Ne (B) O2 (C) Ar (D) Xe

D

5.The effect that increasing the temperature has on the pressure may be explained by the kinetic molecular theory as due to (A) the increase in force with which the gas molecules collide with the container walls (B) the increase in rotational energy of the gas molecules (C) the increase in average velocity of the gas molecules, which causes a corresponding increase in the frequency of collisions with the container walls (D) a combination of (A) and (C)

D

6.Hydrogen gas can be prepared by the addition of hydrochloric acid to a sample of zinc. Upon completion of the reaction, 195 mL of gas were collected by water displacement at 25°C and 753 torr. What mass of the hydrogen gas was collected? Pwater = 24 torr at 25°C. (A) 0.00765 g (B) 0.0164 g (C) 0.159 g (D) 0.0154 g

D

8. If ideal gas behavior is assumed, what is the density of neon at STP? (A) 1.11 g L−1 (B) 448 g L−1 (C) 0.009 g L−1 (D) 0.901 g L−1

D

8.A compound composed of carbon, hydrogen, and chlorine is allowed to effuse through a pinhole. The rate of effusion for this compound is 0.411 times as fast as neon. What is the correct molecular formula for this compound? (A) CH2Cl2 (B) C2H2Cl2 (C) C2H3Cl (D) CHCl3

D

9.A sample of CO has a pressure of 58 mm Hg and a volume of 155 mL. When the CO is quantitatively transferred to an evacuated 1.00-L flask, the pressure of the gas will be (A) 374 mm Hg (B) 8990 mm Hg (C) 111 mm Hg (D) 8.99 mm Hg

D

9.Under identical conditions gaseous CO2 and CCl4 are allowed to diffuse through a pinhole. If the rate of diffusion of the CO2is 6.3 × 10−2 mol s−1, what is the rate of diffusion of the CCl4? (A) 6.3 × 10−2 mol s−1 (B) 2.2 × 10−1 mol s−1 (C) 1.8 × 10−2 mol s−1 (D) 3.4 × 10−2 mol s−1

D

A sample of He gas (2.35 mol) occupies 57.9 L at 300.0 K and 1.00 atm. The volume of this sample is __________ L at 423 K and 1.00 atm. A) 0.709 B) 57.9 C) 41.1 D) 81.6 E) 1.41

D

In an experiment 2 moles of H2 (g) and 1 mole of O2 (g) were completely reacted, according to the following equation in a sealed container of constant volume and temperature: 2H2 (g) + O2 (g) → 2H2O(g) If the initial pressure in the container before the reaction is denoted as Pi , which of the following expressions gives the final pressure, assuming ideal gas behavior? (A) Pi (B) 2 Pi (C) (3/2)Pi (D) (2/3)Pi

D

Nitrogen gas was collected over water at 25°C. If the vapor pressure of water at 25°C is 23 mmHg, and the total pressure in the container is measured at 781 mmHg, what is the partial pressure of the nitrogen gas? (A) 46 mmHg (B) 551 mmHg (C) 735 mmHg (D) 758 mmHg

D

The pressure in a 12.2 L vessel that contains 2.34 g of carbon dioxide, 1.73 g of sulfur dioxide, and 3.33 g of argon, all at 42eC is __________ mmHg. A) 116 B) 395 C) 134 D) 263 E) 0.347

D

What volume (mL) of sulfur dioxide can be produced by the complete reaction of 3.82 g of calcium sulfite with excess HCl (aq), when the final SO2 pressure is 827 torr at 44eC? A) 1.39 x 10-4 B) 0.106 C) 1.00 x 10-3 D) 761 E) 578

D

Sodium hydride reacts with excess water to produce aqueous sodium hydroxide and hydrogen gas: NaH (s) + H2O (l) ¬ NaOH (aq) + H2 (g) A sample of NaH weighing __________ g will produce 982 mL of gas at 28eC and 765 torr, when the hydrogen is collected over water. The vapor pressure of water at this temperature is 28 torr. A) 0.960 B) 925 C) 0.0388 D) 2.93 E) 0.925

E