CHEM 111 Ch. 5

A gas sample is held at constant pressure. The gas occupies 3.62 L of volume when the temperature is 21.6°C. Determine the temperature at which the volume of the gas is 3.42 L. A) 312 K B) 278 K C) 20.4 K D) 295 K E) 552 K

B) 278 K

If a 17.90-g sample of a gas occupies 10.0 L at STP, what is the molar mass of the gas at 125°C? A) 5.48 g/mol B) 40.1 g/mol C) 18.4 g/mol D) 58.5 g/mol E) Not enough information is given.

B) 40.1 g/mol

A sample of 35.1 g of methane gas has a volume of 3.11 L at a pressure of 2.70 atm. Calculate the temperature. A) 2.92 K B) 46.8 K C) 320 K D) 32.4 K E) 35.0 K

B) 46.8 K

You have a 400-mL container containing 55.0% He and 45.0% Ar by mass at 25°C and 1.5 atm total pressure. You heat the container to 100°C. Calculate the ratio of PHe : PAr. A) 1/1.22 B) 1.22/1 C) 1/12.2 D) 12.2/1 E) none of these

D) 12.2/1

A sample of helium gas occupies 14.7 L at 23°C and 0.956 atm. What volume will it occupy at 40°C and 1.20 atm? A) 19.5 L B) 20.4 L C) 11.1 L D) 12.4 L E) 14.9 L

D) 12.4 L

A vessel with a volume of 26.9 L contains 2.80 g of nitrogen gas, 0.605 g of hydrogen gas, and 79.9 g of argon gas. At 25°C, what is the pressure in the vessel? A) 75.5 atm B) 0.183 atm C) 2.55 atm D) 2.18 atm E) 58.7 atm

D) 2.18 atm

A physics experiment is conducted at a pressure of 14.4 kPa. What is this pressure in mmHg? A) 18.9 mmHg B) 1.92 mmHg C) mmHg D) 108 mmHg E) mmHg

108 mmHg

Gases generally have A)low density B) high density C) closely packed particles D) no increase in volume when temperature is increased E) no decrease in volume when pressure is increased

A)low density

What is the name for the lowest layer of the atmosphere, which is most influenced by human activities? A) stratosphere B) mesosphere C) terrasphere D) troposphere E) ionosphere

D) troposphere

A 41.1-g sample of Ne gas exerts a certain pressure in a container of fixed volume. What mass of Ar is required to exert half the pressure at the same conditions of volume and temperature? A) 81.4 g Ar B) 1.02 g Ar C) 163 g Ar D) 821 g Ar E) 40.7 g Ar

E) 40.7 g Ar

T/F: At the same temperature, lighter molecules have a higher average kinetic energy than heavier molecules.

f

T/F: In the kinetic molecular theory we assume an ideal gas has no mass.

f

t/f The pressure a gas would exert under ideal conditions is always greater than the observed pressure of a real gas.

f

t/f Gases behave most ideally at STP

f

t/f: The diffusion of a gas is faster than the effusion of a gas.

f

The local weather forecaster reports that the current barometric pressure is 30.4 inches of mercury. What is the current pressure in atmospheres? A) 1.02 atm B) 10.29 atm C) 1.00 atm D) 4.05 atm E) 910 atm

A) 1.02 atm

Gaseous chlorine is held in two separate containers at identical temperature and pressure. The volume of container 1 is 1.30 L, and it contains 6.70 mol of the gas. The volume of container 2 is 2.33 L. How many moles of the gas are in container 2? A) 12.0 mol B) 20.3 mol C) 0.452 mol D) 3.74 mol E) none of these

A) 12.0 mol

Calcium hydride combines with water according to the equation: Beginning with 84.0 g of CaH2 and 42.0 g of H2O, what volume of H2 will be produced at 273 K and a pressure of 1327 torr? A) 29.9 L B) 15.0 L C) L D) 25.7 L E) none of these

A) 29.9 L

A mixture of KCl and KClO3 weighing 1.34 grams was heated; the dry O2 generated occupied 143 mL at STP. What percent of the original mixture was KClO3, which decomposes as follows: A) 38.9% B) 58.4% C) 87.6% D) 10.7% E) 23.7%

A) 38.9%

A 7.94-g piece of solid CO2 (dry ice) is allowed to sublime in a balloon. The final volume of the balloon is 1.00 L at 301 K. What is the pressure of the gas? A) 4.46 atm B) atm C) 3.11 atm D) 0.224 atm E) none of these

A) 4.46 atm

It is found that 250. mL of a gas at STP has a mass of 0.700 g. What is the molar mass? A) 62.7 g/mol B) 2.80 g/mol C) 15.9 g/mol D) 11.2 g/mol E) 128 g/mol

A) 62.7 g/mol

Order the following in increasing rate of effusion: F2, Cl2, NO, NO2, CH4 A) Cl2 < NO2 < F2 < NO < CH4 B) Cl2 < F2 < NO2 < CH4 < NO C) CH4 < NO2 < NO < F2 < Cl2 D) CH4 < NO < F2 < NO2 < Cl2 E) F2 < NO < Cl2 < NO2 < CH4

A) Cl2 < NO2 < F2 < NO < CH4

Of the following real gases, which would be expected to have the lowest van der Waals correction for intermolecular attractions? A) H2 B) Cl2 C) NH3 D) O2 E) not enough information to determine

A) H2

For which gas do the molecules have the highest average velocity? A) He B) Cl2 C) CH4 D) NH3 E) all gases the same

A) He

Which of the following would represent the greatest pressure? A) 0.680 atm B) 517 mmHg C) 11.4 psi D) 62106 Pa E) 14.1 in Hg

C) 11.4 psi

You fill a balloon with 2.50 moles of gas at 22°C at a pressure of 1.62 atm. What is the volume of the balloon? A) 15.7 L B) 98.0 L C) 37.4 L D) 2.79 L E) 22.4 L

C) 37.4 L

Zinc metal is added to hydrochloric acid to generate hydrogen gas, which is collected over a liquid whose vapor pressure is the same as pure water at 20.0°C (18 torr). The volume of the gas mixture is 1.7 L and its total pressure is 0.810 atm. 84. Determine the partial pressure of the hydrogen gas in this mixture. A) 562 torr B) 580 torr C) 598 torr D) 616 torr E) 634 torr

C) 598 torr

Consider a sample of gas in a container on a comfortable spring day. The Celsius temperature suddenly doubles, and you transfer the gas to a container with twice the volume of the first container. If the original pressure was 12 atm, what is a good estimate for the new pressure? A) 3 atm B) 5.5 atm C) 6.4 atm D) 12 atm E) 15 atm

C) 6.4 atm

The valve between a 5-L tank containing a gas at 9 atm and a 10-L tank containing a gas at 6 atm is opened. Calculate the final pressure in the tanks. A) 3 atm B) 4 atm C) 7 atm D) 15 atm E) none of these

C) 7 atm

Which of the following statements is true concerning ideal gases? A) The temperature of the gas sample is directly related to the average velocity of the gas particles. B) At STP, 1.0 L of Ar(g) contains about twice the number of atoms as 1.0 L of Ne(g) since the molar mass of Ar is about twice that of Ne. C) A gas exerts pressure as a result of the collisions of the gas molecules with the walls of the container. D) The gas particles in a sample exert attraction for one another. E) All of the above are false.

C) A gas exerts pressure as a result of the collisions of the gas molecules with the walls of the container.

All the following are postulates of the kinetic-molecular theory of gases except: A) The collisions between molecules are elastic. B) The gas molecules are in constant motion. C) At a constant temperature, each molecule has the same kinetic energy. D) The volumes of the molecules are negligible compared with the volume of the container. E) The gas molecules are in rapid motion.

C) At a constant temperature, each molecule has the same kinetic energy.

When 0.72 g of a liquid is vaporized at 110°C and 0.967 atm, the gas occupies a volume of 0.559 L. The empirical formula of the gas is CH2. What is the molecular formula of the gas? A) CH2 B) C2H4 C) C3H6 D) C4H8 E) none of these

C) C3H6

One way to isolate metals from their ores is to react the metal oxide with carbon as shown in the following reaction: If 34.08 g of a metal oxide reacted with excess carbon and 4.37 L of CO2 formed at 100°C and 1.50 atm, what is the identity of the metal? A) Hg B) Mg C) Cu D) Cd E) Zn

C) Cu

You have two samples of the same gas in the same size container, with the same pressure. The gas in the first container has a Kelvin temperature four times that of the gas in the other container. The ratio of the average velocity of particles in the first container compared to that in the second is A) 1:1 B) 4:1 C) 1:4 D) 2:1 E) 1:2

D) 2:1

A gaseous mixture containing 1.5 mol Ar and 3.5 mol CO2 has a total pressure of 7.3 atm. What is the partial pressure of CO2? A) 2.2 atm B) 1.4 atm C) 17 atm D) 5.1 atm E) 7.3 atm

D) 5.1 atm

An excess of sodium hydroxide is treated with 26.5 L of dry hydrogen chloride gas measured at STP. What is the mass of sodium chloride formed? A) 1.55 kg B) 1.69 g C) 0.138 kg D) 69.1 g E) 13.3 g

D) 69.1 g

The temperature of a specific amount of gas in a sealed container changes from 20.0°C to 40.0°C. If the volume remains constant, the pressure will change from 755 mmHg to A) 1510 mmHg B) 707 mmHg C) 378 mmHg D) 807 mmHg E) 755 mmHg

D) 807 mmHg

Consider three 1-L flasks at STP. Flask A contains NH3 gas, flask B contains NO2 gas, and flask C contains N2 gas. 22. Which contains the largest number of molecules? A) Flask A B) Flask B C) Flask C D) All are the same. E) More information is need to answer this.

D) All are the same.

Which of the following statements is false? A) The density of a gas is directly proportional to the external pressure. B) The density of helium gas is double that of hydrogen gas. C) The density of a gas is indirectly proportional to the temperature in Kelvin. D) All gases have the same density at STP. E) The density of a gas is independent of the volume.

D) All gases have the same density at STP.

Which of the following would have a higher rate of effusion than C2H2? A) N2 B) O2 C) Cl2 D) CH4 E) CO2

D) CH4

Complete the following: Because real gas particles have attraction for one another: A) Real gases act most ideally at STP. B) We assume gas particles have negligible (zero) volume. C) One mole of an ideal gas at STP has a volume of 22.4 L. D) Real gases act more ideally at higher temperatures and lower pressures. E) At least two of the above statements (A-D) correctly complete the statement.

D) Real gases act more ideally at higher temperatures and lower pressures.

A gas is found to diffuse at half the rate of methane (CH4). Which of the following could be this gas? A) O2 B) N2 C) CO2 D) SO2 E) C2H6

D) SO2

Which of the following is not an assumption of the kinetic molecular theory for a gas? A) Gases are made up of tiny particles in constant chaotic motion. B) Gas particles are very small compared to the average distance between the particles. C) Gas particles collide with the walls of their container in elastic collisions. D) The average velocity of the gas particles is directly proportional to the absolute temperature. E) All of the above are assumptions of the kinetic molecular theory.

D) The average velocity of the gas particles is directly proportional to the absolute temperature.

Which of the following effects will make PV/nRT less than one for a real gas? A) The gas molecules are large enough to occupy a substantial amount of space. B) A large number of molecules have speeds greater than the average speed. C) The gas molecules have a very low molar mass. D) The gas molecules attract one another. E) None of these.

D) The gas molecules attract one another.

Three 1.00-L flasks at 25°C and 725 torr contain the gases CH4 (flask A), CO2 (flask B), and C2H6 (flask C). 27. In which flask is there 0.039 mol of gas? A) Flask A B) Flask B C) Flask C D) all E) none

D) all

For which gas are the collisions elastic? A) He B) Cl2 C) CH4 D) NH3 E) all gases the same

E) all gases the same

The purity of a sample containing zinc and weighing 0.312 g is determined by measuring the amount of hydrogen formed when the sample reacts with an excess of hydrochloric acid. The determination shows the sample to be 84.0% zinc. What amount of hydrogen (measured at STP) was obtained? A) L B) g C) mole D) molecules E) atoms

D) molecules

At a given temperature and pressure, a sample of Gas A is observed to diffuse twice as fast as a sample of a different gas, B. Based on this: A) The molar mass of A is one fourth that of B B) The molar mass of A is one half that of B C) The molar mass of A is 0.707 times that of B D) The molar mass of A is 1.414 times that of B E) The molar mass of A is four times that of B

A) The molar mass of A is one fourth that of B

Determine the number of moles of hydrogen gas present in the sample. A) 42 mol B) 0.82 mol C) 1.3 mol D) 0.056 mol E) 22 mol

D) 0.056 mol

A 3.31-g sample of lead nitrate, , molar mass = 331 g/mol, is heated in an evacuated cylinder with a volume of 2.37 L. The salt decomposes when heated, according to the equation: Assuming complete decomposition, what is the pressure in the cylinder after decomposition and cooling to a temperature of 300. K? Assume the takes up negligible volume. A) 0.260 atm B) 0.208 atm C) 0.0519 atm D) 0.364 atm E) 34.4 atm

A) 0.260 atm

A sample of N2 gas is contaminated with a gas (A) of unknown molar mass. The partial pressure of each gas is known to be 200. torr at 25°C. The gases are allowed to effuse through a pinhole, and it is found that gas A escapes at 4 times the rate of N2. The molar mass of gas A is: A) 1.75 g/mol B) 112 g/mol C) 7.01 g/mol D) 448 g/mol E) none of these

A) 1.75 g/mol

Mercury vapor contains Hg atoms. What is the volume of 201 g of mercury vapor at 822 K and 0.512 atm? A) 132 L B) L C) 175 L D) 34.5 L E) 17.3 L

A) 132 L

You are holding two balloons, an orange balloon and a blue balloon. The orange balloon is filled with neon (Ne) gas and the blue balloon is filled with argon (Ar) gas. The orange balloon has twice the volume of the blue balloon. Which of the following best represents the mass ratio of Ne:Ar in the balloons? A) 1:1 B) 1:2 C) 2:1 D) 1:3 E) 3:1

A) 1:1

Into a 2.22-liter container at 25°C are placed 1.23 moles of O2 gas and 3.20 moles of solid C (graphite). If the carbon and oxygen react completely to form CO(g), what will be the final pressure in the container at 25°C? A) 27.1 atm B) 13.5 atm C) 2.27 atm D) 35.2 atm E) none of these

A) 27.1 atm

Avogadro's law states that: A) Equal amounts of gases occupy the same volume at constant temperature and pressure. B) The volume of a fixed amount of gas is inversely proportional to its pressure at constant temperature. C) The volume of a fixed amount of gas is directly proportional to its temperature in Kelvin at constant pressure. D) The total pressure of a mixture of gases is the simple sum of the partial pressure of all of the gaseous compounds. E) The rates of effusion of gases are inversely proportional to the square roots of their molar masses.

A) Equal amounts of gases occupy the same volume at constant temperature and pressure.

Which of the following is not a postulate of the kinetic molecular theory? A) Gas particles have most of their mass concentrated in the nucleus of the atom. B) The moving particles undergo perfectly elastic collisions with the walls of the container. C) The forces of attraction and repulsion between the particles are insignificant. D) The average kinetic energy of the particles is directly proportional to the absolute temperature. E) All of the above are postulates of the kinetic molecular theory.

A) Gas particles have most of their mass concentrated in the nucleus of the atom.

You are holding four identical balloons each containing 10.0 g of a different gas. The balloon containing which gas is the largest balloon? A) H2 B) He C) Ne D) O2 E) All have the same volume.

A) H2

Which of the following properties of a real gas is related to the b coefficient in the van der Waals equation? A) Real gases consist of molecules or atoms that have volume. B) The average speed of the molecules of a real gas increases with temperature. C) There are attractive forces between atoms or molecules of a real gas. D) The rate of effusion of a gas is inversely proportional to the square root of the molecular weight of the gas. E) None of these.

A) Real gases consist of molecules or atoms that have volume.

You carry out the reaction represented by the following balanced equation: N2(g) + 3H2(g) → 2NH3(g) You add an equal number of moles of nitrogen and hydrogen gases in a balloon. The volume of the balloon is 1.00 L before any reaction occurs. Determine the volume of the balloon after the reaction is complete. Assume constant temperature. A) 0.330 L B) 0.670 L C) 1.00 L D) 1.50 L E) 3.00 L

B) 0.670 L

The standard temperature for gases is A) 100°C B) 0°C C) 32°C D) 212°F E) 0°F

B) 0°C

Consider a sample of helium gas in a container fitted with a piston, as pictured below. The piston is frictionless, but has a mass of 10.0 kg. How many of the following processes will cause the piston to move away from the base and decrease the pressure of the gas? Assume ideal behavior. 10.0 kg ↓ base ↑ I. heating the helium II. removing some of the helium from the container III. turning the container on its side IV. decreasing the pressure outside the container A) 0 B) 1 C) 2 D) 3 E) 4

B) 1

Standard pressure for gases is A) 0 atm B) 1 atm C) 100 atm D) dependent upon temperature E) none of the above

B) 1 atm

Body temperature is about 309 K. On a cold day, what volume of air at 276 K must a person with a lung capacity of 2.2 L breathe in to fill the lungs? A) 2.46 L B) 1.97 L C) 2.08 L D) 3.93 L E) none of these

B) 1.97 L

What volume of measured at STP is produced by the combustion of 6.27 g of natural gas according to the following equation? A) 8.76 L B) 17.5 L C) 4.38 L D) 19.1 L E) 3.14 L

B) 17.5 L

A balloon has a volume of 2.32 liters at 24.0°C. The balloon is heated to 48.0°C. Calculate the new volume of the balloon. A) 2.32 L B) 2.51 L C) 2.15 L D) 4.64 L E) 1.16 L

B) 2.51 L

What volume of carbon dioxide measured at STP will be formed by the reaction of 1.47 mol of oxygen with 0.900 mol of ethyl alcohol, CH3CH2OH? A) 40.3 mL B) 22.0 L C) 32.9 L D) 49.4 L E) 0.980 L

B) 22.0 L

An automobile tire is filled with air at a pressure of 27.0 lb/in2 at 25°C. A cold front moves through and the temperature drops to 5°C. Assuming no change in volume, what is the new tire pressure? A) 5.40 lb/in2 B) 25.2 lb/in2 C) 28.9 lb/in2 D) 135 lb/in2 E) 4.63 lb/in2

B) 25.2 lb/in2

What volume is occupied by 21.0 g of methane (CH4) at 27°C and 1.25 atm? A) 37.2 L B) 25.8 L C) 2.32 L D) L E) not enough data to calculate

B) 25.8 L

A mixture is prepared from 15.0 L of ammonia and 15.0 L chlorine measured at the same conditions; these compounds react according to the following equation: When the reaction is completed, what is the volume of each gas (NH3, Cl2, N2, and HCl, respectively)? Assume the final volumes are measured under identical conditions. A) 0.00 L, 5.00 L, 7.50 L, 45.0 L B) 5.00 L, 0.00 L, 5.00 L, 30.0 L C) 0.00 L, 0.00 L, 7.50 L, 45.0 L D) 0.00 L, 0.00 L, 5.00 L, 30.0 L E) 0.00 L, 10.0 L, 15.0 L, 90.0 L

B) 5.00 L, 0.00 L, 5.00 L, 30.0 L

The mass of 1.12 liters of gas Y at STP is found to be 6.23 g. The density of gas Y is A) 10.6 g/L B) 5.56 g/L C) 15.6 g/L D) 0.200 g/L E) 0.180 g/L

B) 5.56 g/L

The air pressure in the inner tube of a tire on a typical racing bike is held at a pressure of about 112 psi. Convert this pressure to atm. A) 0.147 atm B) 7.62 atm C) 0.112 atm D) 0.131 atm E) 112 atm

B) 7.62 atm

Which of the following is included as a postulate in the kinetic molecular theory of an ideal gas? A) The distance between gas molecules is small compared with the size of the molecule. B) All collisions between molecules are elastic. C) In an average collision between molecules, both molecules have the same kinetic energy. D) All molecules move randomly in zigzag directions. E) All the molecules have the same velocity.

B) All collisions between molecules are elastic.

A 1.00-g sample of a gaseous compound of boron and hydrogen occupies 0.820 L at 1.00 atm and 3°C. What could be the molecular formula for the compound? A) BH3 B) B2H6 C) B4H10 D) B3H12 E) B5H14

B) B2H6

For which gas are the molecules diatomic? A) He B) Cl2 C) CH4 D) NH3 E) all gases the same

B) Cl2

Four identical 1.0-L flasks contain the gases He, Cl2, CH4, and NH3, each at 0°C and 1 atm pressure. 46. Which gas has the highest density? A) He B) Cl2 C) CH4 D) NH3 E) all gases the same

B) Cl2

What would happen to the average kinetic energy of the molecules of a gas sample if the temperature of the sample increased from 20°C to 40°C? A) It would double. B) It would increase. C) It would decrease. D) It would become half its value. E) Two of these.

B) It would increase.

Use the kinetic molecular theory of gases to predict what would happen to a closed sample of a gas whose temperature increased while its volume decreased. A) Its pressure would decrease. B) Its pressure would increase. C) Its pressure would hold constant. D) The number of moles of the gas would decrease. E) The average kinetic energy of the molecules of the gas would decrease.

B) Its pressure would increase.

Which of the following is true about the kinetic molecular theory? A) The volume of a gas particle is considered to be small - about 0.10 mL. B) Pressure is due to the collisions of the gas particles with the walls of the container. C) Gas particles repel each other, but do not attract one another. D) Adding an ideal gas to a closed container will cause an increase in temperature. E) At least two of the above statements are correct.

B) Pressure is due to the collisions of the gas particles with the walls of the container.

You have a certain mass of helium gas (He) in a rigid steel container. You add the same mass of neon gas (Ne) to this container. Which of the following best describes what happens? Assume the temperature is constant. A) The pressure in the container doubles. B) The pressure in the container increases but does not double. C) The pressure in the container more than doubles. D) The volume of the container doubles. E) The volume of the container more than doubles.

B) The pressure in the container increases but does not double.

Boyle's law states that: A) Equal amounts of gases occupy the same volume at constant temperature and pressure. B) The volume of a fixed amount of gas is inversely proportional to its pressure at constant temperature. C) The volume of a fixed amount of gas is directly proportional to its temperature in Kelvin at constant pressure. D) The total pressure of a mixture of gases is the simple sum of the partial pressure of all of the gaseous compounds. E) The rates of effusion of gases are inversely proportional to the square roots of their molar masses.

B) The volume of a fixed amount of gas is inversely proportional to its pressure at constant temperature.

Hydrogen and chlorine gases react to form HCl. You and a friend are on opposite sides of a long hallway, you with H2 and your friend with Cl2. You both want to form HCl in the middle of the room. Which of the following is true? A) You should release the H2 first. B) Your friend should release the Cl2 first. C) You both should release the gases at the same time. D) You need to know the length of the room to answer this question. E) You need to know the temperature to answer this question.

B) Your friend should release the Cl2 first.

Real gases are those that A) only behave ideally at high pressures or low temperatures B) deviate from ideal behavior C) are only available naturally in the earth's atmosphere D) are called real gases because their behavior can easily be modeled E) have an even number of protons

B) deviate from ideal behavior

According to the postulates of the kinetic theory of gases, the average speed of the molecules of a given gas is proportional to the A) absolute temperature squared B) square root of the absolute temperature C) absolute temperature D) Celsius temperature squared E) reciprocal of the absolute temperature

B) square root of the absolute temperature

The van der Waals equation, nRT = [P + a(n/V)2] (V - nb), incorporates corrections to the ideal gas law in order to account for the properties of real gases. One of the corrections accounts for A) the possibility of chemical reaction between molecules B) the finite volume of molecules C) the quantum behavior of molecules D) the fact that average kinetic energy is inversely proportional to temperature E) the possibility of phase changes when the temperature is decreased or the pressure is increased

B) the finite volume of molecules

What volume of oxygen gas at STP is needed to react with 5.75 mol of ? A) 17.3 L B) 42.9 L C) L D) L E) Not enough information is given to solve the problem.

C) L

Oxygen gas, generated by the reaction is collected over water at 27°C in a 1.55-L vessel at a total pressure of 1.00 atm. (The vapor pressure of H2O at 27°C is 26.0 torr.) How many moles of KClO3 were consumed in the reaction? A) 0.0608 moles B) 0.0912 moles C) 0.0405 moles D) 0.0434 moles E) 1.50 moles

C) 0.0405 moles

A balloon contains an anesthetic mixture of cyclopropane (cp) and oxygen (O2) at 171 torr and 570. torr, respectively. What is the ratio of the number of moles of cyclopropane to moles of oxygen? A) 3.33 B) 0.230 C) 0.300 D) 0.390 E) 0.460

C) 0.300

The partial pressures of CH4, N2, and O2 in a sample of gas were found to be 135 mmHg, 508 mmHg, and 571 mmHg, respectively. Calculate the mole fraction of nitrogen. A) 20.4 B) 0.470 C) 0.418 D) 0.751 E) 0.359

C) 0.418

A glass column is filled with mercury and inverted in a pool of mercury. The mercury column stabilizes at a height of 729 mm above the pool of mercury. What is the pressure of the atmosphere? A) 1.04 atm B) 0.729 atm C) 0.959 atm D) 456 atm E) 0.639 atm

C) 0.959 atm

Air has an average molar mass of 29.0 g/mol. The density of air at 0.97 atm and 30.0°C is: A) 29.0 g/L B) 39.0 g/mL C) 1.13 g/L D) 1.35 g/mL E) 11.4 g/L

C) 1.13 g/L

Calculate the ratio of the effusion rates of N2 and N2O. A) 0.637 B) 1.57 C) 1.25 D) 0.798 E) 1.61

C) 1.25

Given reaction 2NH3(g) + 3Cl2(g) → N2(g) + 6HCl(g), you react 5.0 L of NH3 with 5.0 L of Cl2 measured at the same conditions in a closed container. Calculate the ratio of pressures in the container (Pfinal/Pinitial). A) 0.75 B) 1.00 C) 1.33 D) 1.50 E) none of these

C) 1.33

You have a 400-mL container containing 55.0% He and 45.0% Ar by mass at 25°C and 1.5 atm total pressure. You heat the container to 100°C. 89. Calculate the total pressure. A) 1.20 atm B) 1.50 atm C) 1.88 atm D) 2.01 atm E) none of these

C) 1.88 atm

The mass of 1.12 liters of gas Y at STP is found to be 6.23 g. The molar mass of gas Y is A) 56.0 g/mol B) 89.0 g/mol C) 125 g/mol D) 140. g/mol E) 157 g/mol

C) 125 g/mol

You have two samples of the same gas in the same size container, with the same pressure. The gas in the first container has a Kelvin temperature four times that of the gas in the other container. 25. The ratio of the number of moles of gas in the first container compared to that in the second is A) 1:1 B) 4:1 C) 1:4 D) 2:1 E) 1:2

C) 1:4

Argon has a density of 1.78 g/L at STP. How many of the following gases have a density at STP greater than that of argon? Cl2 He NH3 NO2 A) 0 B) 1 C) 2 D) 3 E) 4

C) 2

For an ideal gas, which pairs of variables are inversely proportional to each other (if all other factors remain constant)? 1. V and T 2. T and n 3. n and V 4. P and T A) 1 and 2 only B) 3 and 4 only C) 2 only D) 1 and 3 only E) 1, 3, and 4 only

C) 2 only

The valve between the 2.00-L bulb, in which the gas pressure is 1.80 atm, and the 3.00-L bulb, in which the gas pressure is 3.00 atm, is opened. What is the final pressure in the two bulbs, the temperature remaining constant? A) 0.720 atm B) 2.28 atm C) 2.52 atm D) 1.80 atm E) 2.40 atm

C) 2.52 atm

A 3.60-L sample of carbon monoxide is collected at 55°C and 0.869 atm. What volume will the gas occupy at 1.05 atm and 25°C? A) 1.35 L B) 3.95 L C) 2.71 L D) 3.28 L E) none of these

C) 2.71 L

You have 41.6 g of O2 gas in a container with twice the volume as one with CO2 gas. The pressure and temperature of both containers are the same. Calculate the mass of carbon dioxide gas you have in the container. A) 57.2 g B) 0.650 g C) 28.6 g D) 2.60 g E) none of these

C) 28.6 g

What volume does 40.5 g of N2 occupy at STP? A) 64.8 L B) 1.81 L C) 32.4 L D) 50.7 L E) none of these

C) 32.4 L

Consider three 1-L flasks at STP. Flask A contains NH3 gas, flask B contains NO2 gas, and flask C contains N2 gas. In which flask are the molecules least polar and therefore most ideal in behavior? A) Flask A B) Flask B C) Flask C D) All are the same. E) More information is needed to answer this.

C) Flask C

At 200 K, the molecules or atoms of an unknown gas, X, have an average velocity equal to that of Ar atoms at 400 K. What is X? (Assume ideal behavior.) A) He B) CO C) HF D) HBr E) F2

C) HF

At 1000°C and 10. torr, the density of a certain element in the gaseous state is . The element is: A) F B) He C) Na D) Zn E) Hg

C) Na

Which of the following pollutant gases is not produced directly in a combustion engine? A) CO B) CO2 C) O3 D) NO E) NO2

C) O3

Calculate the density of nitrogen at STP. A) 0.312 g/L B) 0.625 g/L C) 0.800 g/L D) 1.25 g/L E) 1.60 g/L

D) 1.25 g/L

Consider the following containers, one with helium at 27°C and the other with argon at 27°C. Which of the following statements are true? A) The speed of each atom of helium is 926 m/s. B) The rms speed of the He and the Ar atoms are the same. C) The average kinetic energy of the two samples are equal. D) All of the above are true. E) None of the above are true.

C) The average kinetic energy of the two samples are equal.

Charles's law states that: A) Equal amounts of gases occupy the same volume at constant temperature and pressure. B) The volume of a fixed amount of gas is inversely proportional to its pressure at constant temperature. C) The volume of a fixed amount of gas is directly proportional to its temperature in Kelvin at constant pressure. D) The total pressure of a mixture of gases is the simple sum of the partial pressure of all of the gaseous compounds. E) The rates of effusion of gases are inversely proportional to the square roots of their molar masses.

C) The volume of a fixed amount of gas is directly proportional to its temperature in Kelvin at constant pressure.

Which statement is inconsistent with the kinetic theory of an ideal gas? A) The forces of repulsion between gas molecules are very weak or negligible. B) Most of the volume occupied by a gas is empty space. C) When two gas molecules collide, they both gain kinetic energy. D) The average kinetic energy of a gas is proportional to the absolute temperature. E) Gas molecules move in a straight line between collisions.

C) When two gas molecules collide, they both gain kinetic energy.

A plastic bag is weighed and then filled successively with two gases, X and Y. The following data are gathered: Temperature: 0.0°C (273 K) Pressure: 1.00 atmosphere Mass of empty bag: 20.77 g Mass of bag filled with gas X: 24.97 g Mass of 1.12 liters of air at conditions given: 1.30 g Volume of bag: 1.12 liter Molar volume at STP: 22.4 liters The bag is emptied and refilled, successively, with gases X and Y, this time at 1 atm pressure and a temperature 30°C higher. Assume that the volume of the bag is the same as before. Which one of the following statements is wrong? A) The full bag contains fewer molecules of each gas than it did at 0.0°C. B) The ratio of the density of gas Y to the density of gas X is the same as at 0.0°C. C) The molar masses of the two gases are the same as they were at 0.0°C. D) The mass of each gas filling the bag is now 303/273 times the mass held at 0.0°C. E) The average velocity of the molecules of gas X at 30°C is higher than it was at 0.0°C.

D) The mass of each gas filling the bag is now 303/273 times the mass held at 0.0°C.

Consider the following gas samples: Sample A Sample B S2(g) O2(g) n = 1 mol n = 2 mol T = 800 K T = 400 K P = 0.20 atm P = 0.40 atm Which of the following statements is false? A) The volume of sample A is twice the volume of sample B. B) The average kinetic energy of the molecules in sample A is twice the average kinetic energy of the molecules in sample B. C) The fraction of molecules in sample A, having a kinetic energy greater than some high fixed value, is larger than the fraction of molecules in sample B, having kinetic energies greater than that same high fixed value. D) The mean square velocity of molecules in sample A is twice as large as the mean square velocity of molecules in sample B. E) Assuming identical intermolecular forces in the two samples, sample A should be more nearly ideal than sample B.

D) The mean square velocity of molecules in sample A is twice as large as the mean square velocity of molecules in sample B.

Dalton's law of partial pressures states that: A) Equal amounts of gases occupy the same volume at constant temperature and pressure. B) The volume of a fixed amount of gas is inversely proportional to its pressure at constant temperature. C) The volume of a fixed amount of gas is directly proportional to its temperature in Kelvin at constant pressure. D) The total pressure of a mixture of gases is the sum of the partial pressure of all of the gaseous compounds. E) The rates of effusion of gases are inversely proportional to the square roots of their molar masses.

D) The total pressure of a mixture of gases is the sum of the partial pressure of all of the gaseous compounds.

Pressure is A) defined as the mass that an object exerts when at rest B) measured in Newtons C) defined as the number of moles of substance divided by the mass of the substance D) defined as the force per unit area E) measured in grams

D) defined as the force per unit area

A gas sample is heated from -20.0°C to 57.0°C and the volume is increased from 2.00 L to 4.50 L. If the initial pressure is 0.140 atm, what is the final pressure? A) 0.0477 atm B) -0.177 atm C) 0.411 atm D) 0.242 atm E) 0.0811 atm

E) 0.0811 atm

For a gas, which two variables are directly proportional to each other (if all other conditions remain constant)? 1. T and n 2. V and n 3. V and T A) 1 only B) 2 only C) 3 only D) 1 and 2 only E) 2 and 3 only

E) 2 and 3 only

A sample of gas is in a 50.0-mL container at a pressure of 645 torr and a temperature of 25°C. The entire sample is heated to a temperature of 35°C and transferred to a new container whose volume is 98.7 mL. The pressure of the gas in the second container is about: A) 457 torr B) 316 torr C) torr D) 65 torr E) 338 torr

E) 338 torr

Three 1.00-L flasks at 25°C and 725 torr contain the gases CH4 (flask A), CO2 (flask B), and C2H6 (flask C). In which single flask do the molecules have the greatest mass, the greatest average velocity, and the highest kinetic energy? A) Flask A B) Flask B C) Flask C D) All are the same. E) No one flask has all these.

E) No one flask has all these.

Given a cylinder of fixed volume filled with 1 mol of argon gas, which of the following is correct? (Assume all gases obey the ideal gas law.) A) If the temperature of the cylinder is changed from 25°C to 50°C, the pressure inside the cylinder will double. B) If a second mole of argon is added to the cylinder, the ratio T/P would remain constant. C) A cylinder of identical volume filled with the same pressure of helium must contain more atoms of gas because He has a smaller atomic radius than argon. D) Two of the above. E) None of the above.

E) None of the above.

Graham's law states that: A) Equal amounts of gases occupy the same volume at constant temperature and pressure. B) The volume of a fixed amount of gas is inversely proportional to its pressure at constant temperature. C) The volume of a fixed amount of gas is directly proportional to its temperature in Kelvin at constant pressure. D) The total pressure of a mixture of gases is the simple sum of the partial pressure of all of the gaseous compounds. E) The rates of effusion of gases are inversely proportional to the square roots of their molar masses.

E) The rates of effusion of gases are inversely proportional to the square roots of their molar masses.

Which of the following statements is least likely to be true of a sample of nitrogen gas? A) Molecules of gaseous nitrogen are in constant random motion. B) The pressure exerted by gaseous nitrogen is due to collisions of the molecules with the walls of the container. C) The average kinetic energy of the gaseous nitrogen is proportional to the absolute temperature of the gas. D) Collisions between the gaseous molecules are elastic. E) The volume of the sample would be zero at -273°C.

E) The volume of the sample would be zero at -273°C.

For which gas do the molecules have the smallest average kinetic energy? A) He B) Cl2 C) CH4 D) NH3 E) all gases the same

E) all gases the same

Which gas sample has the greatest number of molecules? A) He B) Cl2 C) CH4 D) NH3 E) all gases the same

E) all gases the same

Which conditions of P, T, and n, respectively, are most ideal? A) high P, high T, high n B) low P, low T, low n C) high P, low T, high n D) low P, high T, high n E) low P, high T, low n

E) low P, high T, low n

A 142-mL sample of gas is collected over water at 22°C and 753 torr. What is the volume of the dry gas at STP? (The vapor pressure of water at 22°C = 20. torr) A) 122 mL B) 162 mL C) 136 mL D) 111 mL E) none of these

E) none of these

Which of the following is the best qualitative graph of P versus molar mass of a 1-g sample of different gases at constant volume and temperature? A) B) C) D) E) none of these

E) none of these

The SI unit of pressure is the A) ampere B) kilojoule C) newton D) gram E) pascal

E) pascal