What is meant by an ideal gas?

An ideal gas is one that obeys the equation pV = nRT at all pressures and temperatures, having molecules of negligible volume that exert no forces on one another except during collisions.

The mole is the amount of substance that contains exactly 6.02214076 × 10²³ elementary entities, the Avogadro constant; this is very nearly the number of atoms in 12 g of carbon-12, the definition used before 2019.

How is the number of moles of a gas found from its mass?

The number of moles is the mass of the sample divided by the molar mass, n = m/M, with mass and molar mass in the same units.

CCEA A-Level Physics 1210

Physical Quantities, Scalars and Vectors

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Thermal Physics

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Thermal Physics

The ideal gas equation pV = nRT

3 things to know
Unit A2 1

Overview

Ideal gas and value and unit of the molar gas constant.

What you need to know

Answer each one before you reveal it.

Your recallNot started

Key term

State the ideal gas equation in the form using the number of moles, and define every symbol.

Key term

State the value and unit of the molar gas constant.

Numbers

Calculate the pressure of 2.0 mol of an ideal gas occupying 0.050 m³ at 300 K.

Questions from this subtopic

Each one with the model answer underneath.

1
State the ideal gas equation in the form using the number of moles, and define every symbol.
Model answer
pV = nRT, where p is the pressure in Pa, V the volume in m³, n the number of moles, R the molar gas constant of 8.31 J K⁻¹ mol⁻¹ and T the absolute temperature in K.
2
What is meant by an ideal gas?
Model answer
An ideal gas is one that obeys the equation pV = nRT at all pressures and temperatures, having molecules of negligible volume that exert no forces on one another except during collisions.
3
State the value and unit of the molar gas constant.
Model answer
The molar gas constant is R = 8.31 J K⁻¹ mol⁻¹.
4
Define the mole.
Model answer
The mole is the amount of substance that contains exactly 6.02214076 × 10²³ elementary entities, the Avogadro constant; this is very nearly the number of atoms in 12 g of carbon-12, the definition used before 2019.
5
How is the number of moles of a gas found from its mass?
Model answer
The number of moles is the mass of the sample divided by the molar mass, n = m/M, with mass and molar mass in the same units.
6
Calculate the pressure of 2.0 mol of an ideal gas occupying 0.050 m³ at 300 K.
Model answer
p = nRT/V = 2.0 × 8.31 × 300/0.050 = 1.0 × 10⁵ Pa to two significant figures.

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The ideal gas equation pV = nRT

Overview

What you need to know

State the ideal gas equation in the form using the number of moles, and define every symbol.

State the value and unit of the molar gas constant.

Calculate the pressure of 2.0 mol of an ideal gas occupying 0.050 m³ at 300 K.

Questions from this subtopic

State the ideal gas equation in the form using the number of moles, and define every symbol.

What is meant by an ideal gas?

State the value and unit of the molar gas constant.

Define the mole.

How is the number of moles of a gas found from its mass?

Calculate the pressure of 2.0 mol of an ideal gas occupying 0.050 m³ at 300 K.

Other ways to work this

What is inside Levo

The 3-step method, run for you

Cram a whole paper in one sitting

Blank Blitz makes facts automatic

Build It gets the exam shape right

Test It catches misconceptions

Brain Breaks between sessions

Every question in Thermal Physics, on a schedule.