Chapter 9 Open Stax Chemistry

atmosphere (ATM)

unit of pressure, 1 atm = 760 mmHg

Avodagro's law

V₁/n₁ = V₂/n₂

barometer

an instrument used to measure atmospheric pressure

Dalton's Law of Partial Pressure

Ptotal=P₁+P₂+P₃

ideal gas

assumed to have no attractions between molecules

ideal gas law

PV=nRT

ideal gas constant

0.0821 (atm * L)/(mol * K)

partial pressure

The pressure exerted by a component of a gas mixture.

pressure

the measure of how much force is acting on a given area

combined gas law

P₁V₁/T₁ = P₂V₂/T₂

standard temperature and pressure (STP)

273.15 K and 1 atm or 760 mmHg

A ___ is an instrument used to measure atmospheric pressure specifically in the area of meteorology.

barometer

What gas has the greatest kinetic energy at STP?

All gases have the same kinetic energy

What is the standard pressure for 1.00 mole of gas at STP?

760 mm Hg

What is the temperature for STP conditions?

273.15 K

For a gas, which pair of variables are inversely proportional to each other (if all other conditions remain constant)?

Pressure and volume

What is the volume for 1.00 mole of gas at STP?

22.4 L

The molecular weight of mixing gases and their rates of diffusion are related _____.

Inversely

The rates of diffusion of two gases and their densities are related ___.

Indirectly

The pressure of a gas in a container is 1.85 atm and it occupies a volume of 12.5 L. If the original volume is reduced by half at constant temperature, what would happen to the pressure?

the pressure would double

Your car is equipped with tire pressure monitoring system (TPMS) and the tire pressure is 34.0 psi on a 98°F day in California. You decided to take a road trip to Alaska where the temperature drops to 20°F. As you arrived in Alaska, you noticed that the TPMS alert light is illuminated. Why did this happen?

As temperature decreases, gas molecules lose kinetic energy and the volume of gas is reduced thus reducing the overall pressure in the tire which results in the TPMS becoming activated.

On a hot summer day, you notice that a bag of chips left in your vehicle has inflated. Why did this happen?

As temperature increases, gas molecules gain kinetic energy and the volume of gas increases inside the bag of chips.

One way to state Boyle's Law is "All other things being equal, the pressure of a gas is inversely proportional to its volume." What are the "other things" that must be equal?

number of moles and temperature

Boyle's Law

The volume of a given amount of gas held at constant temperature varies inversely with the applied pressure when the temperature and mass are constant.

Charles' Law

The volume of a given amount of gas held at constant pressure is directly proportional to the Kelvin temperature.

Avogadro's Law

Gives the relationship between volume and amount when pressure and temperature are held constant. Remember amount is measured in moles. Also, since volume is one of the variables, that means the container holding the gas is flexible in some way and can expand or contract.
If the amount of gas in a container is increased, the volume increases. If the amount of gas in a container is decreased, the volume decreases.

Dalton's Law of Partial Pressures

The total pressure of a mixture of non-reacting gases is the sum of their individual partial pressures.