Chapter 14 Chemistry Study Guide

How many moles of N₂ are in a flask with a volume of 250 mL at a pressure of 300.0 kPa and a temperature of 300.0 K?

250 mL x 1 L/1000 mL=0.25 L n=P x PV/RT= 300.0 kPa x 0.25 L/ 8.31 x 300.0 K=0.030 mol

What is the pressure exerted by 32 g of O₂ in a 22.0-L container at 30.0°C?

32 g O₂ x 1 mol O₂/ 32 g O₂= 1 mol O₂ P= nRT/V= 1.0 mol x 8.31 x 303 K/ 22.0 L= 110 kPa

Compressibility

A measure of how much the volume of matter decreases under pressure

When a container is filled with 3.00 moles of H₂, 2.00 moles of O₂, and 1.00 mole of N₂, the pressure in the container is 768 kPa. What is the partial pressure of O₂? A. 256 kPa B. 128 kPa C. 128 kPa D. 101.0 kPa

A. 256 kPa

Which of the following gases is the best choice for inflating a balloon that must remain inflated for a long period? A. Argon B. Oxygen C. Hydrogen D. Neon

A. Argon

An ideal gas CANNOT be _____. A. Condensed B. Cooled C. Heated D. Compressed

A. Condensed

How does the gas propellant move when an aerosol can is used? A. From a region of high pressure to a region of lower pressure B. From a region of high pressure to a region of equally high pressure C. From a region of low pressure to a region of higher pressure D. From a region of low pressure to a region of equally low pressure

A. From a region of high pressure to a region of lower pressure

If a sealed syringe is plunged into cold water, in which direction will the syringe piston slide? A. In B. Out C. No movement will occur D. The direction cannot be predicted

A. In

If a balloon is heated, what happens to the pressure of the air inside the balloon if the volume remains constant? A. It increases B. It stays the same C. It decreases D. The change cannot be predicted

A. It increases

If a balloon is heated, what happens to the volume of the air in the balloon if the pressure is constant? A. It increases B. It stays the same C. It decreases D. The change cannot be predicted

A. It increases

What happens to the partial pressure of oxygen in a sample of air if the temperature is increased? A. It increases B. It stays the same C. It decreases D. The change cannot be determined

A. It increases

If a balloon is squeezed, what happens to the pressure of the gas inside the balloon? A. It increases. B. It stays the same. C. It decreases. D. The pressure depends on the type of gas in the balloon.

A. It increases.

At high pressures, how does the volume of a real gas compare with the volume of an ideal gas under the same conditions? A. It is much greater B. It is much less C. There is no difference D. It depends on the type of gas

A. It is much greater

The volume of a gas is doubled while the temperature is held constant. How does the gas pressure change? A. It is reduced by one-half. B. It does not change. C. It is doubled. D. It varies depending on the type of gas.

A. It is reduced by one-half.

When the Kelvin temperature of an enclosed gas doubles, the particles of the gas _____. . A. Move faster B. Strike the walls of the container with less force C. Decrease in average kinetic energy D. Decrease in volume

A. Move faster

What does the ideal gas law allow a scientist to calculate that the other gas laws do not? A. Number of moles B. Pressure C. Volume D. Temperature

A. Number of moles

Why does air escape from a tire when the tire valve is opened? A. The pressure outside the tire is lower than the pressure inside the tire. B. The pressure outside the tire is greater than the pressure inside the tire. C. The temperature is higher outside the tire than inside the tire. D. There are more particles of air outside the tire than inside the tire

A. The pressure outside the tire is lower than the pressure inside the tire.

If 4 moles of gas are added to a container that already holds 1 mole of gas, how will the pressure change inside the container? A. The pressure will be five times higher. B. The pressure will double. C. The pressure will be four times higher. D. The pressure will not change.

A. The pressure will be five times higher.

If the volume of a container of gas is reduced, what will happen to the pressure inside the container? A. The pressure will increase. B. The pressure will not change. C. The pressure will decrease. D. The pressure depends on the type of gas.

A. The pressure will increase.

What happens to the temperature of a gas when it is compressed? A. The temperature increases. B. The temperature does not change. C. The temperature decreases. D. The temperature becomes unpredictable.

A. The temperature increases.

As the temperature of the gas in a balloon decreases, which of the following occurs? A. The volume of the balloon increases. B. The average kinetic energy of the gas decreases. C. The gas pressure inside the balloon increases. D. All of the above

A. The volume of the balloon increases.

Which of these changes would NOT cause an increase in the pressure of a contained gas? A. The volume of the container is increased. B. More of the gas is added to the container. C. The temperature is increased. D. The average kinetic energy of the gas in increased.

A. The volume of the container is increased.

Why does the pressure inside a container of gas increase if more gas is added to the container? A. There is an increase in the number of collisions between particles and the walls of the container. B. There is an increase in the temperature of the gas. C. There is a decrease in the volume of the gas. D. There is an increase in the force of the collisions between the particles and the walls of the container.

A. There is an increase in the number of collisions between particles and the walls of the container.

Boyle's law states that . A.The volume of a gas varies inversely with pressure B. The volume of a gas varies directly with pressure C. The temperature of a gas varies inversely with pressure D. The temperature of a gas varies directly with pressure

A.The volume of a gas varies inversely with pressure

Explain how pumping air into a bicycle tire increases the pressure within the tire.

Adding air increases the number of gas particles in the tire. Collisions of particles with the inside walls of the tire cause the pressure that is exerted by the enclosed gas. Therefore, increasing the number of air particles increases the number of collisions, which in turn increases the pressure within the tire

What are some of the differences between a real gas and an ideal gas?

An ideal gas is one that follows the gas laws at all conditions of pressure and temperature. The behavior of a real gas deviates from the behavior of an ideal gas, particularly at low temperatures and high pressures. Also, kinetic theory assumes that the particles of an ideal gas have no volume and are not attracted to each other. This is not true for real gases. Real gases can be liquefied and sometimes solidified by cooling and applying pressure, but ideal gases cannot.

Explain why the rates of diffusion and effusion, for any particular gas at constant temperature, are proportional to the square root of the molar mass of the gas.

At constant temperature, particles all have the same average kinetic energy. The formula for kinetic energy is KE =1/2 mv². At constant temperature, the KE is constant and the velocity is proportional to the square root of 1/m. Because the diffusion and effusion rates are directly proportional to the velocity at which a particle is moving, these rates are also proportional to the square root of 1/m. So the more mass a particle has, the more slowly it will diffuse or effuse.

Dalton's Law

At constant volume and temperature, the total pressure exerted by a mixture of gases is equal to the sum of the partial pressures of the component gases.

At a certain temperature and pressure, 0.20 mol of carbon dioxide has a volume of 3.1 L. A 3.1-L sample of hydrogen at the same temperature and pressure . A. Has the same mass B. Contains the same number of atoms C. Has a higher density D. Contains the same number of molecules

B. Contains the same number of atoms

At low temperatures and pressures, how does the volume of a real gas compare with the volume of an ideal gas under the same conditions? A. It is greater B. It is less C. There is no difference D. It depends on the type of gas

B. It is less

Under what conditions of temperature of pressure is the behavior of real gases most like that of ideal gases? A. Low temperature and low pressure B. Low temperature and high pressure C. High temperature and low pressure D. High temperature and high pressure

B. Low temperature and high pressure

If the atmospheric pressure on Mt. Everest is one-third the atmospheric pressure at sea level, the partial pressure of oxygen on Everest is ______. A. One-sixth its pressure at sea level B. One-third its pressure at sea level C. One-half its pressure at sea level D. Equal to its pressure at sea level

B. One-third its pressure at sea level

Which of the following is constant for 1 mole of any ideal gas? A. PVT B. PV/T C. PT/V D. VT/P

B. PV/T

Charles's law states that . A. The pressure of a gas is inversely proportional to its temperature in kelvins B. The volume of a gas is directly proportional to its temperature in kelvins C. The pressure of a gas is directly proportional to its temperature in kelvins D. The volume of a gas is inversely proportional to its temperature in kelvins

B. The volume of a gas is directly proportional to its temperature in kelvins

A breathing mixture used by deep-sea divers contains helium, oxygen, and carbon dioxide. What is the partial pressure of oxygen at 101.4 kPa if PHe = 82.5 kPa and PCO₂ =0.4 kPa? A. 82.9 kPa B. 19.3 kPa C. 18.5 kPa D. 101.0 kPa

C. 18.5 kPa

If a balloon containing 3000 L of gas at 39°C and 99 kPa rises to an altitude where the pressure is 45.5 kPa and the temperature is 16°C, the volume of the balloon under these new conditions would be calculated using the following conversion factor ratios: A. 3000 L x 99/45.5 x 16/39 B. 3000 L x 312/289 x 45.5/99 C. 3000 L x 289/312 x 99/44.5 D. 3000 L x 39/16 x 45.5/99

C. 3000 L x 289/312 x 99/44.5

A sample of gas occupies 17 mL at -112°C. What volume does the sample occupy at 70°C? A. 10.6 mL B. 27 mL C. 36 mL D. 8.0 mL

C. 36 mL

What happens when a piston is used to decrease the volume of a contained gas? A.Fewer gas particles exert a force on the piston. B. The piston's pressure on the gas becomes greater than the pressure exerted by the gas on the piston. C. Gas particles become compressed. D. Gas particles leak out of the container.

C. Gas particles become compressed.

Which law can be used to calculate the number of moles of a contained gas? A. Boyle's law B. Combined gas law C. Ideal gas law D. Charles's law

C. Ideal gas law

If oxygen is removed from a sample of air as iron rusts, what happens to the partial pressure of oxygen in the air? A. It increases B. It stays the same C. It decreases D. The change cannot be determined

C. It decreases

If oxygen is removed from a sample of air as iron rusts, what happens to the total pressure of the air? A. It increases B. It stays the same C. It decreases D. The change cannot be determined

C. It decreases

The volume of a gas is reduced from 4 L to 0.5 L while the temperature is held constant. How does the gas pressure change? A. It increases by a factor of four B. It decreases by a factor of eight C. It increases by a factor of eight D. It increases by a factor of two

C. It increases by a factor of eight

If the volume of a container of air is reduced by one-half, what happens to the partial pressure of oxygen within the container? A. It is reduced by one-half B. It does not change C. It is doubled D. It is reduced by one-fourth

C. It is doubled

How is the ideal gas law usually written? A. PV/nT=R B. PV/T=nR C. PV=nRT D. P=nRT/V

C. PV=nRT

What happens to the pressure of a gas inside a container if the temperature of the gas decreases? A. The pressure increases B. The pressure does not change C. The pressure decreases D. The pressure cannot be predicted

C. The pressure decreases

When the temperature and number of particles of a gas are constant, which of the following is also constant? A. The sum of the pressure and volume B. The difference of the pressure and volume C. The product of the pressure and volume D. The ratio of the pressure and volume

C. The product of the pressure and volume

A gas occupies a volume of 2.4 L at 14.1 kPa. What volume will the gas occupy at 84.6 kPa? A. 497 L B. 2.5 L C. 14 L D. 0.40 L

D. 0.40 L

The tendency of molecules to move toward areas of lower concentration is called _____. A. Suffusion B. Suspension C. Effusion D. Diffusion

D. Diffusion

Which of the following atoms would have the greatest velocity if each atom had the same kinetic energy? A. Bromine B. Chlorine C. Ammonia D. Hydrogen

D. Hydrogen

Which of the following gases will effuse the most rapidly? A. Bromine B. Chlorine C. Ammonia D. Hydrogen

D. Hydrogen

As the temperature of a fixed volume of a gas increases, the pressure will _____? A. Vary inversely B. Decrease C. Not Change D. Increase

D. Increase

The combined gas law relates which of the following? A. Pressure and volume only B. Temperature and pressure only C. Volume and temperature only D. Temperature, pressure, and volume

D. Temperature, pressure, and volume

If a sealed syringe is heated, in which direction will the syringe plunger move? A. Out B. In C. The plunger will not move D. The direction cannot be predicted

D. The direction cannot be predicted

A box with a volume of 22.4 L contains 1.0 mol of nitrogen and 2.0 mol of hydrogen at 0°C. Which of the following statements is true? A. The total pressure in the box is 101 kPa. B. The partial pressures of N₂ and H₂ are equal. C. The total pressure is 202 kPa D. The partial pressure of N₂ is 101 kPa.

D. The partial pressure of N₂ is 101 kPa.

In general, for a gas at a constant volume, _____. A. The pressure of the gas is inversely proportional to its temperature in kelvins B. The volume of the gas is inversely proportional to its temperature in kelvins C. The volume of the gas is directly proportional to its temperature in kelvins D. The pressure of the gas is directly proportional to its temperature in kelvins

D. The pressure of the gas is directly proportional to its temperature in kelvins

When the volume and number of particles of a gas are constant, which of the following is also constant? A. The sum of the pressure and temperature in kelvins B. The difference of the pressure and temperature in kelvins C. The product of the pressure and temperature in kelvins D. The ratio of the pressure and temperature in kelvins

D. The ratio of the pressure and temperature in kelvins

When the pressure and number of particles of a gas are constant, which of the following is also constant? A. The sum of the volume and temperature in kelvins B. The difference of the volume and temperature in kelvins C. The product of the volume and temperature in kelvins D. The ratio of the volume and temperature in kelvins

D. The ratio of the volume and temperature in kelvins

Why is a gas easier to compress than a liquid or a solid? A. Its volume increases more under pressure than an equal volume of liquid does. B. Its volume increases more under pressure than an equal volume of solid does. C. The space between gas particles is much less than the space between liquid or solid particles. D. The volume of a gas's particles is small compared to the overall volume of the gas.

D. The volume of a gas's particles is small compared to the overall volume of the gas.

What is Dalton's law of partial pressures? Explain how this law relates to the fact that mountain climbers must carry tanks of oxygen when scaling high peaks.

Dalton's law of partial pressures states that, at constant volume and temperature, the total pressure exerted by a mixture of gases is equal to the sum of the partial pressures of the individual gases in the mixture. Mountain climbers carry oxygen tanks because at high altitudes, the total air pressure is much lower than it is at sea level and the partial pressure of oxygen in the air is correspondingly lower, also. This low partial pressure of oxygen is not sufficient to support respiration.

Boyle's Law

For a given mass of gas at constant temperature, the volume of the gas varies inversely with pressure.

Ideal gas law

PV=nRT

A mixture of gases at a total pressure of 95 kPa contains N₂, CO₂, and O₂. The partial pressure of the CO₂ is 24 kPa and the partial pressure of the N₂ is 48 kPa. What is the partial pressure of the O₂?

Po₂=Ptotal-(Pco₂ + Pn₂)= 95 kPa - (48 kPa + 24 kPa)=23 kPa

A 10-g mass of krypton occupies 15.0 L at a pressure of 210 kPa. Find the volume of the krypton when the pressure is increased to 790 kPa.

P₁ x V₁= P₂ x V₂ 210 kPa x 15.0 L= 790 kPa x V₂ 210 kPa x 15.0 L/ 790 kPa=V₂ V₂=4.0 L

A gas has a pressure of 710 kPa at 227°C. What will its pressure be at 27°C, if the volume does not change?

P₁/T₁=P₂/T₂; 710 kPa/500 kPa= P₂/300 K 710 kPa x 300 K/ 500 K=P₂ P₂= 470 kPa

A rigid container of O₂ has a pressure of 340 kPa at a temperature of 713 K. What is the pressure at 273 K?

P₂=P₁ x T₂/T₁=340 kPa x 273 K/ 713 K= 140 kPa

Use Graham's law to calculate how much faster fluorine gas, F₂, will effuse than chlorine gas, Cl₂, will. The molar mass of F₂=38.0; the molar mass of Cl₂ =70.9.

Rate F₂/Rate Cl₂= √70.9/38.0=1.4

Diffusion

Tendency of molecules to move to regions of lower concentration

How does the air pressure in a balloon change when the balloon is squeezed? Explain why this change occurs.

The air pressure increases. Squeezing reduces the enclosed volume of the balloon without changing the number of particles in the balloon. Consequently, the number of collisions between the particles and the balloon increases.

Effusion

The escape of gas through a small hole in a container

Partial pressure

The pressure exerted by a gas in a mixture

How does the pressure of an enclosed gas in a rigid container change when the gas is heated? Explain why this change occurs

The pressure increases when the gas is heated because increasing the temperature of the gas increases the average kinetic energy of the particles in the gas. With an increase in average kinetic energy, there will be an increase in the number of collisions between the particles and the container walls. In addition, because the particles are moving faster, on average, the collisions will occur with greater force. Both factors, the increased frequency of collision and the increased force of the collisions, contribute to the increase in pressure.

Gay-Lussac's Law

The pressure of a gas is directly proportional to its Kelvin temperature if the volume is kept constant.

Graham's Law

The rate at which a gas will effuse is inversely proportional to the square root of the gas's molar mass.

Charles's Law

The volume of a fixed mass of gas is directly proportional to its Kelvin temperature, if the pressure is kept constant.

A gas occupies a volume of 140 mL at 35.0°C and 97 kPa. What is the volume of the gas at STP?

V₂=P₁ x V₁ x T₂/T₁ x P₂ V₂= 97 kPa x 140 mL x 273 K/ 308 K x 101 kPa=120 mL

A gas storage tank has a volume of 3.5 x 10⁵ m³ when the temperature is 27°C and the pressure is 101 kPa. What is the new volume of the tank if the temperature drops to -10°C and the pressure drops to 95 kPa?

V₂=P₁ x V₁ x T₂/T₁ x P₂= (101 kPa) x (3.5 x 10⁵ m³) x 263 K/ 300 K x 95 kPa V₂= 3.26 x 10⁵ m³

The volume of a gas is 250 mL at 340.0 kPa pressure. What will the volume be when the pressure is reduced to 50.0 kPa, assuming the temperature remains constant?

V₂=V₁ x P₁/P₂=250 mL x 340.0 kPa/50.0 kPa=1700 mL

A balloon filled with helium has a volume of 30.0 L at a pressure of 100 kPa and a temperature of 15.0°C. What will the volume of the balloon be if the temperature is increased to 80.0°C and the pressure remains constant?

V₂=V₁ x T₂/T₁=30.0 L x 353 K/288 K=34.3 L

A gas has a volume of 590 mL at a temperature of -55.0°C. What volume will the gas occupy at 30.0°C?

V₂=V₁ x T₂/T₁=590mL x 303 K/218 K= 820mL

The gaseous product of a reaction is collected in a 25.0-L container at 27°C. The pressure in the container is 300.0 kPa and the gas has a mass of 96.0 g. How many moles of the gas are in the container?

n=PV/RT= 300.0 kPa x 25 L/ 8.31 x 300 K=3.0 mol