UNIT 4: INTRODUCTION TO GAS LAWS

How to find partial pressure?

(Mols of gas/total moles of all gas - n)*(total pressure - P)

What is 273K in Celsius?

0 degrees

What is R in PV=nRt?

0.0821 L atm/mol K; gas law constant

How to convert Liters to mol to grams?

1 mol/22.4 L

How to do gas stoichiometry?

1. Balance. 2. Use balanced number ratio. Ex: if there was 3.40 ml of K3, and we needed to find K, we would need to balance. Then, the ratio will be 3.40 K3*3K/1K.

Explain how to find the amount of grams of O2 is needed to fill 5 air tanks with a volume of 2200 mL at STP.

1. Convert the mL to L 2. Convert 1. w/22.4/1mol x5 to 2. then divide by molar mass

What are the 4 postulates of Kinetic Molecular Theory?

1. No volume 2. Gas moves in straight lines (ping pong) 3. Elastic collisions (don't stick to each other; no net loss in kinetic energy) 4. Don't attract or repel each other.

STP - Standard Pressure (atmosphere)

1.00 atm

STP - Standard Pressure (kPa)

101.325 kPa

STP - Standard Pressure (PA)

101325 Pa

STP - Standard Temperature:

273

What is the standard temperature?

273

STP - Standard Pressure (mmHg)

760 mmHg

STP - Standard Pressure (torr)

760 torr

How to know what is mass a and b in Graham's Law?

A is the lighter/faster gas (molar mass/rate) and B is the heavier/slower gas.

What is the lowest temperature possible?

Absolute zero, or zero kelvin. This is when all molecular motion stops.

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

Atm; abbrevation for?

Atmosphere

What law would you use to find a new volume if the initial volume is 5.6L at 560 mmHg at standard pressure?

Boyle's Law.

If 60L of hydrogen gas at 546K is cooled to 273 K at constant pressure, what gas law would you use to find the new volume of the gas would be?

Charles' Law

The volume of a sample gas at 273C is 200L. If the volume is decreased to 100L at constant pressure, what law will you use to find the new temperature of the gas?

Charles' Law

What law would you use to find a final temperature of a 10.2L gas at 56C, if the volume is increased to 49L?

Charles' Law.

True or False, If the kinetic energies of H2 and O2 are the same, their velocities are also equal? Why or why not?

False, because in the equation KE=1/2mv^2, the mass affects the equation, so because they have different masses, they won't have the same velocity.

True or False, Boyle's Law demonstrates the relationship between volume and temperature. Why or why not?

False, it is pressure and volume.

True or False, Charles' Law represents the relationship between volume and pressure? Why or why not?

False, it is the volume and temperature.

Avogadro's Law represents the relationship between moles and temperature?

False, only pressure and volume.

How to find the partial pressure of He if there is 3.0g of He and 21g of Ne mixed at 51C w/a pressure of 93.3 atm? What law is that?

Find moles of given grams. Add up to total moles of (n) Solve for P in PV=nRT Use the equation (gas mol/total mol)(P) Ideal Gas Law

What leads to an increase in kinetic energy?

Higher temperature

Molar volume lab: you collected H2 gas under H2O, what are two ways to find the gas pressure?

If given the initial pressure (p1 or total pressure), and the amount of moles for each component, we can use the equation (gas mol/total mol)(total pressure). Because gas pressure is a partial pressure, this will find it. Another way is to find the atmospheric pressure, and the partial pressure of the water. The atmospheric pressure is the total amount of pressure, and given another partial pressure of a component, you can use Dalton's to find the gas pressure.

How do you figure out what mass of a gas diffuses at a rate slower than mass a?

If it is a slow rate, the unknown gas is heavier. The rate ratio will be 1:slow rate. W/molar mass of mass a, find mass b to find the gas. Equal the rate ratio to sqrt(mass b or unknown/mass a); remember mass b is slower.

If the temperature is at a constant, what does this mean for the kinetic energy of gases?

It must be the same

A cylinder with a tightly fitted piston moves downward. What happens to the amount of molecules in the cylinder?

It stays the same

What is the temp scale, or how to convert Celciu to Kelvin?

K=C+273

What do each term in the equation KE=1/2mv^2 represent?

KE - average kinetic energy m - mass v - velocity

Describe the gas that diffuses more rapidly and then the gas that diffuses more slowly to the other gas.

Lighter, and faster rate gases will diffuse rapidly compared to slower molar mass gases with slow rates.

The higher the kelvin or temperature leads to what effect on average kinetic energy?

Makes it increase

How does the Boyle's Law graph look like?

Negative Exponential Growth. Does not touch any of the axis. Y-axis is P, x-axis is V.

What is Gay-Lussac's equation?

P1/T1 = P2/T2

Combined Gas Law:

P1V1/T1=P2V2/T2

Based on the proportion, what is the equation of Boyle's Law?

P1V1=P2V2

Ideal Gas Law

PV=nRT

Pa; abbreviation for?

Pascals

How does the Gay-Lussac's Law graph look like?

Positive Linear Growth. Touches the origin. Y-axis is P, x-axis is T.

How does the Charles' Law graph look like?

Positive Linear Growth. Touches the origin. Y-axis is V, x-axis is T.

How does the Avogadro's Law graph look like?

Positive Linear Growth. Touches the origin. Y-axis is V, x-axis is n.

Boyle Law's shows that the gas volume is inversely proportional to the

Pressure on the gas when temperature and mole are constant

What law is: When V and mol are constant, the pressure and temperature are directly?

Proportional, this is Gay-Lussac's Law

Based on the definition of Dalton's Theory, what is the appropriate equation?

Ptotal = P1+P2+P3+P...

What are the two equations for Graham's Law?

Rate a/b=sqrt(mass b/a); sqrt(mass b/a)

Average Kinetic energy of all the molecules in a gas is equal to the?

Temperature. Gases at the same temperature will have the same kinetic energy.

At the same temperature, how would you know if a series of gases would effuse first?

The gas with the lowest molar mass will be lighter, which will result in a faster rate compared to the rest.

What is the proportion for Boyle's Law?

The increase of Pressure (P) = the decrease of Volume (V), vice-verca

A perfume bottle is opened at one end of the room and after a few minutes the smell of the perfume can be detected at the other end of the room. How do you explain how the smell traveled across the room?

The perfume molecules diffused throughout the room.

What does Graham's Law find?

The rate of effusion and diffusion

What happens to molecules at 0K?

They stop moving because that is absolute zero.

True or False, Gay Lussac's Law represents the relationship between pressure and temperature. Why or why not?

True.

A gas sample has a volume of 25.0 mL at a pressure of 1.00 atmospheres. If the volume increases to 50.0 mL and the temperature remains constant, what law will you have to use to find the new pressure?

Use Combined Gas Law.

If you have 2 moles of H2, and 4 moles of O2 at STP, describe the process to find the partial pressure of O2

Use following equation: (gas mol/total moles)(total pressure at STP, so 1.00 atm)

What is the equation for Charles Law?

V1/T1 = V2/T2

How to find density?

d=PM/RT

How to find molar mass using an equation with pressure, density, and temperature?

drt/p=m