Ch 14 The Behavior of Gases
Equation for Combined Gas law
(P1 x V1) / T1 = (P2 x V2) / T2
# of moles
1 mol
Pressure
101.3 kPa
Volume
22.4 L
temperature
273 K
gas constant
8.31 L x kPa/K x mol
Why is it dangerous to throw aerosol cans into the fire?
A gas in a sealed container will generate enormous pressure when heated because the particles are moving faster and will more force causing it to explode.
What is Dalton's law of partial pressures?
At constant volume and temperature, the total pressure exerted by a mixture of gases is equal to the sum of the partial pressure of the component gases.
What law states that for a given mass of gas at constant temperature, the volume of the gas caries inversely with pressure?
Boyle's law
Which gas law does this equation represent if temperature is held constant so that T1 = T2?
Boyle's law
Which gas law does this equation represent if pressure is held constant so that P1 = P2
Charles's law
What law states that the pressure of a gas is directly proportional to the Kelvin temperature if the volume remains constant.
Gay-Lussac's law
Which gas law does this equation represent if volume is held constant so that V1 = V2?
Gay-Lussac's law
Equation for Boyle's law
P1 x V1 = P2 x V2
Equation for Gay-Lussac's law
P1/T1 = P2/T2
Equation for Ideal Gas law
PT = nRT
What constant can you calculate when you know the volume occupied by one mole of gas at standard temperature and pressure?
R - gas constant (8.31 L x kPa/K x mole)
Equation for Graham's law
Rate A / Rate B = square root (molar mass B / molar mass A)
In which situations does the combined gas law enable you to do calculations when the other gas laws do not apply?
Situations in which only the amount of gas is constant
What is Graham's law of effusion?
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 gases.
Equation for Charle's law
V1/T1 = V2/T2
How do conditions change inside a rigid container when you use a pump to add gas to the container?
You will be able to generate high pressures by adding more and more gas. Once the pressure exceeds the strength of the container, the container will burst.
When would you use the ideal gas law instead of the combined gas law?
You would use the ideal gas law to calculate the number of moles of a contained gas requiring an expression that contains the variable n.
What conditions are real gases most likely to differ from ideal gases?
at low temperatures and high pressures
How to collect gas?
collecting gas by water displacement or collect gas over water
What is the tendency of molecules in a gas to move from areas of higher concentration to areas of lower concentration?
diffusion
Pressure and temperature (K) are __________ proportional
directly
Volume and temperature (K) are __________ proportional
directly
At a specified temperature and pressure, is the number of moles of gas in a sample directly proportional or inversely proportional to the volume of the sample?
directly proportional
Is the number of moles in a sample of gas directly proportional or inversely proportional to the number of particles of gas in the sample?
directly proportional
T/F: If two objects with different masses have the same kinetic energy, the one with the greater mass must move faster.
false
T/F: Raising the temperature of a contained gas causes its pressure to decrease.
false
T/F: When a sealed container of gas is opened, gas will flow from the region of lower pressure to the region of higher pressure.
false
For what kind of gas is (P x V)/(T x n) a constant for all values of pressure, temperature, and volume under which the gas can exist?
ideal gases
Pressure and volume are _________ proportional
inversley
What happens when the push button on an aerosol spray can is pressed?
it creates an opening between the inside of the can and the air outside causing the gas to flow through the opening to the lower pressure region outside. this movement of the gas forces the paint outside of the can
How does the molar mass of a gas affect the rate at which the gas effuses of diffuses?
lower molar mass diffuse and effuse faster than those with higher molar masses
What is the contribution of the pressure of each gas in a mixture to the total pressure?
partial pressure (exerted by that gas)
What can happen if too much gas is pumped into a sealed, rigid container?
the container will burst
What theory explains the behavior of gases?
the kinetic theory
When the volume is reduced by one half, what happens to the pressure.
the pressure is increased by one half
What does the Combined Law describe?
the relationship among the pressure, temperature, and volume of an enclosed gas
Dalton's law of Partial Pressures:
total pressure is the sum of the partial pressures of the gases
T/F: Charles's law states that when the pressure of a fixed mass of gas is held constant, the volume of the gas is directly proportional to its Kelvin temperature.
true
T/F: Gas pressure depends only on the number of particles in a given volume and on their average kinetic energy. The type of particle does not matter.
true
T/F: If a gas were truly an ideal gas, it would be impossible to liquefy or solidify it by cooling or by applying pressure.
true
T/F: The gas laws of Boyle, Charles, and Gay-Lussac can be combined into a single mathematical expression.
true
T/F: when the temperature of a sample of steam increases from 100 degrees Celsius to 200 degrees Celsius, the average kinetic energy of its particles doubles.
true; the increase in temperature causes the particles to have more energy meaning its kinetic energy and temperature are directly related
