Chapter 14 The Behavior of Gases Test Review
What is Charles's Law?
V1/T1 = V2/T2
Calculate the ratio of the velocity of helium atoms to the velocity of fluorine molecules at the same temperature.
3.08:1
If 4.50 g of methane gas (CH4) is in a 2.00-L container at 35°C, what is the pressure in the container?
3.60 × 102 kPa
What is the volume occupied by 1.24 mol of a gas at 35°C if the pressure is 96.2 kPa?
33.0 L
What do you need to calculate the amount of gas in a sample at given conditions of temperature, pressure, and volume?
an expression that contains the variable n
The more the gas is __________, the greater s the pressure that the gas exerts inside the container.
compressed
Why are gases Easier to compress than solids or liquids are?
space between the particles in a gas.
An increase in the _____________ of an enclosed gas causes an increase in its pressure.
temperature
In __________ law the type of particle is not important
Dalton's
_____________________- 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.
Dalton's Law of Partial pressures
Assuming the gas in a container remains at a constant temperature, how could you increase the gas pressure in the container a hundredfold?
Decrease the volume by 100 times.
Consider four identical 1.00L Flasks containing the following gases, each at 25ºC and 1 atm pressure: H2, O2, NH3, and SO2. Which gas would effuse the fastest if identical pinholes were made in all four flasks?
H2
You can raise the pressure exerted by a contained gas by reducing its _______.
volume
What volume will 12.0 g of oxygen gas (O2) occupy at 25°C and a pressure of 52.7 kPa?
17.6 L
A helium-filled weather balloon has a volume of 2.4 x 10^2 L at 99 kPa pressure and a temperature of 0°C. What is the mass of the helium in the balloon?
42 g
An aerosol spray can with a volume of 325 mL contains 3.00g of propane [C3H8] as a propellant. What is the pressure in atm of the gas in the can at 28ºC?
5.17 atm
A mixture of three gases exerts a pressure of 448 kPa, and the gases are present in the mole ratio 1:2:5. What are the individual gas pressures?
56kPa, 112kPa, and 280kPa
____________ law states that as the temperature of an enclosed gas increases, the volume increases, if the pressure is constant.
Charles's
As a gas is heated, the temperature increases and the average kinetic energy of the particles in the gas ________.
Increases
Graham's Law says that the rate of diffusion of a gas is ___________ proportional to the square root of its ________ mass.
Inversely, Molar
List three factors that can effect gas pressure.
Number of molecules of gas. Temperature. Volume.
What is the ideal gas law?
P x V = n x R x T or PV = nRT
When is the combined gas law used to solve problems?
The combined gas law allows you to do calculations for situations in which only THE AMOUNT OF GAS IS CONSTANT.
In what situations is the combined gas law useful?
The combined gas law allows you to do calculations when the only constant is the amount of gas
An ideal gas differs from a real gas in that the molecules of an ideal gas ___________________.
have no attraction for one another
Temperature is measured in ________.
Kelvins
When solving gas law problems, temperature must always be expressed in _________.
Kelvins
What is Boyle's Law?
P1 x P2 = P2 x V2
Write the mathematical equation for Boyle's law and explain the symbols.
P1 × V1 = P2 × V2; P = pressure; V = volume; the subscript 1 represents the starting conditions; the subscript 2, the final conditions.
Why must Kelvin temperatures be used in calculations that involve gases?
Temperatures measured on the Kelvin scale are directly propor- tional to the average kinetic energy of the particles. Celsius temperatures are not.
What are the three factors that affect gas pressure?
The amount of gas, volume, and temperature
______________- PV=nRT
Ideal Gas Law
Find the volume of a gas in liters if 2.95 mol has a pressure of 0.760 atm at a temperature of 52ºC.
104 L
The gas in a closed container has a pressure of 3.00 x 10^2 kPa at 30°C (303 K). What will the pressure be if the temperature is lowered to -172°C (101 K)?
1.00 × 10^2 kPa
A 3.50-L gas sample at 20°C and a pressure of 86.7 kPa expands to a volume of 8.00 L. The final pressure of the gas is 56.7 kPa. What is the final temperature of the gas, in degrees Celsius?
165ºC
Determine the volume occupied by 0.582 mol of a gas at 15°C if the pressure is 81.8 kPa.
17.0 L
The Combined Gas Law is used when what is constant?
Amount of Gas
_____________ Law states that if temperature is constant, as the pressure of a gas increases, the the volume decreases.
Boyle's
A balloon appears slightly smaller when it is moved from the mountains to the seashore at constant temperature. The best gas law to explain this observation would be _____________.
Boyle's Law
Gas pressure results from what?
Collisions of particles in a gas with an object.
_____________-A Measure of how much the volume of matter decreases under pressure.
Compressibility
__________- The process that occurs when a gas escapes through a tiny hole in its container.
Effusion
Why do aerosol containers display the warning, "Do not incinerate"?
High temperatures increase the pressure of the contents of the container and may cause it to explode.
When the pressure of a gas in a sealed container is __________ than the outside air pressure, the gas will flow out of the container when the container is unsealed.
Higher
An ________ gas is one that follows the gas laws at all conditions of pressure and temperature.
Ideal
_______________- The constant in the ideal gas law with the symbol R and the value 8.31 [L•kPa]/[K•mol]
Ideal Gas Constant
If pressure is constant, how does a change in temperature affect the volume of a gas?
If the pressure is constant, as the temperature increases, the volume increases.
How can you compare the rates of effusion of two gases in a mixture?
The rate of effusion of two gases in a mixture is inversely proportional to the square roots of their molar masses.
Charles's Law is used when what is constant?
Pressure
What are the four variables to describe a gas?
Pressure, Volume, Temperature, and Number of Moles
What is Dalton's law?
Ptotal = P1 + P2 + P3 + . . .
The particles in a ________ gas do have volume, and there are attractions between the particles.
Real
How would the number of particles of two gases compare if their partial pressures in a container were identical?
The number of particles would be equal.
The volume of a weather balloon increases as the balloon rises in the atmosphere. Why doesn't the drop in temperature at higher altitudes cause the volume to decrease?
The outside pressure decreases, causing a greater increase in the balloon's volume.
What happens to the particles in a gas when the gas is compressed?
The space between particles is reduced.
In your own words, state Dalton's law of partial pressure.
The total pressure of a gaseous mixture is equal to the sum of the individual pressures of each gas.
Explain how using a pressure cooker reduces the time required to cook food.
The water boils at a higher temperature, which speeds the cooking process.
What is needed to calculate the amount of gas in a sample at given conditions of volume, temperature, and pressure?
To calculate the number of moles of a contained gas requires an expression that contains the variable n.
In a mixture of gases, how is the total pressure determined?
Total pressure is equal to the sum of the partial pressures of the components.
Gay-Lussac's Law is used when what is constant?
Volume
Explain how Charles's law can be derived from the combined gas law.
When the pressure is constant, P1 = P2, the pressure terms cancel, leaving an equation for Charles' law.
What is The combined Gas Law?
[P1 x V1]/T1 = [P2 x V2]/T2
When a gas is __________or___________, it can condense.
cooled, compressed
If the pressure of the gas in a sealed container is ____________ than the outside air pressure, air will rush into the container when the container is opened.
lower
Gases of _______ molar mass diffuse and effuse faster than gases of __________ molar mass.
lower, higher
When a Gas is pumped into a closed rigid container, the __________ increases, as more particles are added.
pressure
A sealed cylinder of gas contains nitrogen gas at 1.00 x 10^3 kPa pressure and a temperature of 20°C. When the cylinder is left in the sun, the temperature of the gas increases to 50°C. What is the new pressure in the cylinder?
1.10 × 10^3 kPa
What pressure is exerted by 0.450 mol of a gas at 25°C if the gas is in a 0.650-L container?
1.71 × 10^3 kPa
Calculate the volume of a gas (in L) at a pressure of 1.00 x 10^2 kPa if its volume at 1.20 x 10^2 kPa is 1.50 x 10^3 mL.
1.80 L
A gas with a volume of 4.0 L at 90.0 kPa expands until the pressure drops to 20.0 kPa. What is its new volume if the temperature doesn't change?
18 L
During an effusion experiment, a certain num- ber of moles of an unknown gas passed through a tiny hole in 75 seconds. Under the same condi- tions, the same number of moles of oxygen gas passed through the hole in 30 seconds. What is the molar mass of the unknown gas?
2.0 x 10^2g
A certain gas effuses four times as fast as oxygen (O2). What is the molar mass of the gas?
2.0g
At 46ºC and 0.880 atm pressure, a gas occupies a volume of 0.600L. How many liters will it occupy at 0ºC and 0.205 atm?
2.20L
Calculate the ratio of the velocity of helium atoms to the velocity of neon atoms at the same temperature.
2.25:1
A given mass of air has a volume of 6.00 L at 101 kPa. What volume will it occupy at 25.0 kPa if the temperature does not change?
24.2 L
A gas with a volume of 3.00 x 10^2 mL at 150.0°C is heated until its volume is 6.00 x 10^2 mL. What is the new temperature of the gas if the pressure remains constant during the heating process?
846 K (573°C)
The photograph shows a tube with cotton balls at each end. The cotton ball at the left was soaked with hydrochloric acid. The cotton ball on the right was soaked with a solution of ammonia. When these compounds react, they form a white solid, ammonium chloride. Based on the location of the ammonium chloride in the tube, which gas diffuses at a faster rate, hydrogen chloride or ammonia? Explain.
Ammonia diffuses faster than hydrogen chloride. Based on the location of the reaction product, the ammonia molecules travel about twice the distance of the hydrogen chloride molecules, in the same time.
Explain why gas pressure decreases when gas is removed from a container with a fixed volume.
As particles are removed from the container, there is a decrease in the number of collisions.
A teacher adds 1 mL of water to an empty metal soda can. The teacher heats the can over a burner until the water boils and then quickly plunges the can upside down in an ice-water bath. The can immediately collapses inward as though crushed in a trash compactor. Use kinetic theory to explain why the can collapsed inward.
Boiling the water fills the can with steam. When the can is plunged upside down into ice water the steam is trapped and rapidly condenses, reducing gas pressure inside the can. The walls of the can are not strong enough to withstand the comparatively high atmospheric pressure, which crushes the can.
Explain why the rates of diffusion of nitrogen gas and carbon monoxide are almost identical at the same temperature.
Carbon monoxide and nitrogen have almost identical molar masses when the masses are rounded to two significant figures (28 g).
__________ law allows you to do calculations for situations in which only the amount of gas is constant.
Combined Gas
What is the motion of Gases?
Constant and Random due to that there are no significant forces of attraction or repulsion among particles in a gas.
With _________ and _________, the type of particle is important.
Effusion, diffusion
How does kinetic theory explain the compressibility of gases?
Gases are easily compressed because there is a lot of space between the particles.
Why is a gas easy to compress?
Gases are easily compressed because there is space between the molecules of a gas.
How does the molar mass of a gas affect the rate at which the gas effuses or diffuses?
Gases of lower molar mass diffuse and effuse faster than gases of higher molar mass.
What is the effect of molar mass on rates of diffusion and effusion?
Gases with lower molar masses diffuse and effuse faster than gases with higher molar masses.
Why does a balloon filled with helium deflate more quickly than a balloon filled with air?
Helium atoms have a smaller molar mass than oxygen and nitrogen molecules and effuse faster through pores in the balloon.
Which gas effuses faster: hydrogen or chlorine? How much faster?
Hydrogen gas diffuses faster than chlorine gas by an approximate factor of six.
How are the pressure, volume, and temperature of a gas related?
If the temperature is constant, as the pressure of a gas increases, the volume decreases.
How are the pressure and volume of a gas related at constant temperature?
If the temperature is constant, the volume of a gas decreases as the pressure increases.
What is the relationship between the temperature and pressure of a contained gas at constant volume?
If the volume is constant, as the temperature increases, the pressure increases.
How is the total pressure of a mixture of gases related to the partial pressures of the component gases?
In a mixture of gases, the total pressure is the sum of the partial pressures of the gases.
Describe an ideal gas.
Its particles have no volume, there are no attractions between them, and collisions are elastic. An ideal gas follows the gas laws at all temperatures and pressures.
Pressure is measured in ________.
Kilopascals
Volume is measured in _______.
Liters
For gases, the SI units for volume[V], Pressure[P], and Temperature[T] are ________________________________.
Liters, Kilopascals, and Kelvins
In a ________ of gases, the total pressure is the sum of the partial pressures of the gases.
Mixture
Which gas effuses faster at the same temperature: molecular oxygen or atomic argon?
Molecular oxygen
Does an ideal gas exist?
No
[N] in the equation PV=nRT represents what?
Number of moles
What is Gay-Lussac's Law?
P1/T1 = P2/T2
Write the mathematical expression for the combined gas law.
P1V1)/T1 = (P2V2)/T2
_______________- The contribution each gas in a mixture of gases makes to the total pressure
Partial Pressure
Explain why it is impossible for an ideal gas to exist.
Particles in a real gas have a finite volume and are attracted to one another at low temperatures and high pressures.
By adding Gas you increase the number of ___________, thus increasing the number of _________, which explains why the gas pressure increases.
Particles, Collisions
What is Graham's Law?
RateA/RateB = √Molar MassB/Molar MassA
________ Gases behave very much like an ideal gas.
Real
Under what conditions are real gases most likely to differ from ideal gases?
Real Gases differ most from an ideal gas at low temperatures and high pressures.
Boyle's Law is used when what is constant?
Temperature
When ___________ is constant you can delete the ratio from the rearranged combined gas law.
Temperature
Explain why heating a contained gas that is held at a constant volume increases its pressure.
The increased kinetic energy of the particles causes collisions to occur more frequently and with more force.
Explain the reasons why real gases deviate from ideal behavior.
The particles in a real gas have a finite volume and are attracted to one another.
A metal cylinder contains 1 mol of nitrogen gas. What will happen to the pressure if another mole of gas is added to the cylinder, but the temperature and volume do not change?
The pressure doubles.
If a gas is compressed from 4 L to 1 L and the temperature remains constant, what happens to the pressure?
The pressure quadruples.
The manufacturer of an aerosol deodorant packaged in a 150mL container plans to produce a container of the same size that will hold twice as much gas. How will the pressure of the gas in the new product compare with that of the gas in the original container?
The pressure will double.
A teacher adds 1 mL of water to an empty metal soda can. The teacher heats the can over a burner until the water boils and then quickly plunges the can upside down in an ice-water bath. The can immediately collapses inward as though crushed in a trash compactor. If the experiment were done with a dry can, would the results be similar? Explain.
The results would be much less dramatic.The change in volume (and in internal pressure) from heated air to cold air is much less dramatic than when steam (a vapor) condenses to water (a liquid).
The ratio of two variables is always a constant. What can you conclude about the relationship between the two variables?
The variables are directly proportional.
If the temperature is constant, what change in volume would cause the pressure of an enclosed gas to be reduced to one quarter of its original value?
The volume and the pressure change in an INVERSE relationship. As one gets bigger the other gets smaller: To reduce the pressure of a gas by 4 times you need to increase the volume by 4 times.
Describe what happens to the volume of a balloon when it is taken outside on a cold winter day. Explain why the observed change happens.
The volume decreases. The mol- ecules have less kinetic energy and cause less pressure on the inside of the balloon.
Write the mathematical equation for Charles's law and explain the symbols.
V1/T1 = V2/T2 V1 and V2 are the initial and final volumes; T1 and T2 are the initial and final temperatures.
Show how Gay-Lussac's law can be derived from the combined gas law.
When the volume is constant, V1 = V2, so the volume terms cancel, leaving the equation for Gay-Lussac's law.
What is the combined gas law with amount of moles included?
[P1 x V1/T1 x n1] = [P2 x V2/T2 x n2]
Compared to liquids and solids, gases are easily compressed because the particles in a gas ___________________.
are spaced relatively far apart.
If the the number of particles is _________, the pressure will double.
doubled
If the volume of a gas in a container were reduced to one-fifth the original volume at constant temperature, the pressure of the gas in the new volume would be ____________ .
five times the original pressure
Why does a collision with an air bag cause less damage than a collision with a steering wheel?
An air bag is filled with gas which is compressible. It allows the body to compress gases instead of hitting a solid wheel. The gases absorb the momentum of the body in a soft gradual fashion instead of an abrupt, brutal way.
What is an ideal gas?
An ideal gas is a gas that follows the gas laws at all conditions of pressure and temperature.
How does a decrease in temperature affect the pressure of a contained gas?
As the temperature of a gas goes up in a closed container, the pressure also goes up. As the temperature goes down, the pressure goes down too.
____________- The tendency of molecules to move toward areas of lower concentration until the concentration is uniform throughout.
Diffusion
What distinguishes effusion from diffusion? How are these processes similar?
During effusion, a gas escapes through a tiny hole in its container. In both cases, the rate depends on the molar mass.
__________ law states that as the temperature of an enclosed increases, the pressure increases, if the volume is constant.
Gay-Lussac's
____________________- The rate of effusion of a gas is inversely proportional to the square root of its molar mass; this relationship is also true for the diffusion of gasses.
Graham's law of effusion
Use the kinetic theory of gases to explain this statement: No gas exhibits ideal behavior at all temperatures and pressures.
In real gases, there are attractions between molecules, and the molecules have volume. At low temperatures, attractions between molecules pull them together and reduce the volume. At high pressures, the volume occupied by the molecules is a significant part of the total volume.
Under what conditions do real gases deviate most from ideal behavior?
Real gases deviate from ideal behavior at low temperatures and high pressures.
Gas Particles move in what type of line paths?
Straight until they collide with other particles or the walls of their container.
How is the partial pressure of a gas in a mixture calculated?
Subtract the partial pressures of the other gases from the total pressure.
