Table of contents

7. Gases

The Ideal Gas Law

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Multiple Choice

A cylinder contains 28.5 L of oxygen gas at a pressure of 1.8 atm and a temperature of 298 K. Using the Ideal Gas Law, how many moles of gas are in the cylinder?

1.50 moles

2.10 moles

3.00 moles

0.75 moles

Verified step by step guidance

Start by recalling the Ideal Gas Law, which is expressed as:

P V = n R T

. Here,

P

is the pressure,

V

is the volume,

n

is the number of moles,

R

is the ideal gas constant, and

T

is the temperature.

Identify the values given in the problem: Pressure

P

= 1.8 atm, Volume

V

= 28.5 L, and Temperature

T

= 298 K.

Use the ideal gas constant

R

= 0.0821 L atm/mol K, which is appropriate for the units of pressure in atm and volume in liters.

Rearrange the Ideal Gas Law to solve for the number of moles

n

n = \frac{P V}{R T}

Substitute the known values into the equation:

n = \frac{1.8 28.5}{0.0821 298}

. Calculate to find the number of moles of oxygen gas in the cylinder.

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