Gas Laws

Question 1

Boyle’s Law

Answer 1

P₁V₁ = P₂V₂

PV = k

The pressure of a gas tends to increase as the volume of the container decreases. Assuming amount and temperature are held constant.

Pressure exerted by an ideal gas is inversely proportional to the volume it occupies.

Question 2

Charles’s Law

Answer 2

V₁/T₁ = V₂/T₂

VT = k

Gases tend to expand when heated.

The relationship between volume and temperature is directly proportional. A gas expands as temperature increases; conversely, a decrease in temperature will lead to a decrease in volume in proportion.

Question 3

Avogadro’s Law

Answer 3

V₁/n₁ = V₂/n₂

V/n = k

Equal volumes of all gases, at the same temperature and pressure, have the same number of molecules

For an ideal gas, the volume and amount (moles) of the gas are directly proportional. As the number of moles of gas increases, the volume of the gas also increases in proportion and vice versa.

Question 4

Gay-Lussac’s Law

Answer 4

P₁/T₁ = P₂/T₂

PT = k

The pressure of a gas of fixed mass and fixed volume is directly proportional to the gas’s absolute temperature. If a gas’s temperature increases, then so does its pressure.

Temperature is a measure of the average kinetic energy of a substance; as the kinetic energy of a gas increases, its particles collide with the container walls more rapidly, thereby exerting increased pressure.

Question 5

Dalton’s Law

Answer 5

P_total = P₁ + P₂ + P₃ . . . P_n

In a mixture of non-reacting gases, the total pressure exerted is equal to the sum of the partial pressures of the individual gases.

Question 6

Combined Gas Law

Answer 6

(P₁V₁)/T₁ = (P2V2)/T2

PV/T = k

The ratio between the pressure-volume product and the temperature of a system is constant.

Question 7

Ideal Gas Law

Answer 7

PV = nRT

Ideal gas model tends to fail at lower temperatures or higher pressures, when intermolecular forces and molecular size become important.

At normal conditions such as standard temperature and pressure, most real gases behave qualitatively like an ideal gas.

One mole of an ideal gas has a volume of 22.4L at STP

Question 8

Density Using Ideal Gas Law

Answer 8

PM = dRT

M = molar mass

d = density (g/L)

P = pressure (atm)

R = constant (.0821)

T = temp (K)