OCR A-Level Physics B H557
Planning
Implementing
Analysis
Evaluation
Practical Skills
Use of Apparatus and Techniques
Fundamental Data Analysis
Imaging and Signalling
Sensing
Mechanical Properties of Materials
Waves and Quantum Behaviour
Space, Time and Motion
Creating Models
Out Into Space
Our Place in the Universe
Matter: Very Simple
Matter: Hot or Cold
Electromagnetism
Charge and Field
Probing Deep Into Matter
Ionising Radiation and Risk
Matter: Very Simple
The equation of state for an ideal gas
- 3 things to know
- Components 01, 02 and 03
Overview
Recall questions on what each symbol means, converting between particle and molar forms, calculating moles, particles and a new pressure, why kelvin is required, and what pressure times volume represents.
What you need to know
Answer each one before you reveal it.
A cylinder of volume 0.020 m³ holds gas at 2.5 × 10⁵ Pa and 300 K. Calculate the number of moles present.
A sealed flask of volume 5.0 × 10⁻⁴ m³ contains gas at 1.0 × 10⁵ Pa and 290 K. Calculate the number of particles.
Questions from this subtopic
Each one with the model answer underneath.
- 1
In pV = NkT, what does each symbol stand for?
Model answer
p is the pressure, V the volume, N the number of particles, k the Boltzmann constant and T the absolute temperature.
- 2
How is the particle form pV = NkT turned into the molar form pV = nRT?
Model answer
Substituting N = nNₐ and R = Nₐ k replaces Nk by nR, so NkT becomes nRT.
- 3
A cylinder of volume 0.020 m³ holds gas at 2.5 × 10⁵ Pa and 300 K. Calculate the number of moles present.
Model answer
n = pV/RT = (2.5 × 10⁵ × 0.020) ÷ (8.31 × 300) = 2.0 mol.
- 4
A sealed flask of volume 5.0 × 10⁻⁴ m³ contains gas at 1.0 × 10⁵ Pa and 290 K. Calculate the number of particles.
Model answer
N = pV/kT = (1.0 × 10⁵ × 5.0 × 10⁻⁴) ÷ (1.38 × 10⁻²³ × 290) = 1.2 × 10²² particles.
- 5
What happens to the pressure of a fixed mass of ideal gas if both its absolute temperature and its volume are doubled?
Model answer
The pressure is unchanged, because pV = NkT and both sides of the relationship double.
- 6
A gas occupying 1.0 m³ at 1.0 × 10⁵ Pa and 300 K is compressed to 0.25 m³ and heated to 450 K. Calculate the new pressure.
Model answer
The new pressure is 1.0 × 10⁵ × (1.0 ÷ 0.25) × (450 ÷ 300) = 6.0 × 10⁵ Pa.
Other ways to work this
The same content, four other ways.
What is inside Levo
Six ways to work the same material.
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