8.4 Ideal Gas Law

A sample of argon gas at STP occupies 56.2 liters. Determine the number of moles of argon and the mass of argon in the sample.

• 101 g

• 110 g

• 100 g

Answer explanation

Solution:

1) Rearrange PV = nRT to this:

n = PV / RT

2) Substitute:

n = [(1.00 atm) (56.2 L) ] / [ (0.08206 L atm mol¯¹ K¯¹) (273.0 K)]

n = 2.50866 mol

3) Multiply the moles by the atomic weight of Ar to get the grams:

2.50866 mol times 39.948 g/mol = 100 g (to three significant figures)

At what temperature will 0.654 moles of neon gas occupy 12.30 liters at 1.95 atmospheres?

• 427 K

• 447 K

• 437 K

Answer explanation

Solution:

1) Rearrange PV = nRT to this:

T = PV / nR

2) Substitute:

T = [(1.95 atm) (12.30 L)] / [(0.654 mol) (0.08206 L atm mol¯¹ K¯¹)]

T = 447 K

Which of the following statements describes an ideal gas?

• Behaves as predicted by the ideal gas law

• Has molecules that do not attract one another

• Has molecules that are considered volumeless

• All of the above

What is the scientific formula for the ideal gas law?

• PV=T

• PV=nRT

• V₁T,=V₂T₂

• PV=0

The IDEAL GAS LAW stated that PV=NkT, where k stands for?

• Kelvin

• Kilogram

• Kepler's Unit

• Boltzmann constant

The IDEAL GAS LAW stated that PV=NkT, where N stands for?

• number of moles

• number of atoms and molecules

• number of atoms

• number of molecules

Determine the Celsius temperature of 2.49 moles of gas contained in a 1.00-L vessel at a pressure of 143 kPa. 

• -266 degrees C
• -622 degrees C
• 622 degrees C 
• 266 degrees C

Determine the number of moles in a container of gas at STP with a volume of 99.2 L. 

• 2222.08 moles
• 4.43 moles
• 22.4 moles 
• 76.8 moles

If the pressure exerted by a gas at 25 degrees C in a volume of 0.044 L is 3.81 atm, how many moles of gas are present?

• .002766 mole
• .0069 mol
• 2.766 mol
• 9.887 mol

In order to solve gas law calculations, temperature must be measured in:

• Fahrenheit
• Celsius
• Kelvin
• It doesn't matter