AQA GCSE Physics
AQA GCSE Physics 4.3.1 Changes of State and the Particle Model Exam Questions
Free AQA GCSE Physics exam questions for 4.3.1 Changes of State and the Particle Model, with a mark scheme for every pack. Covers density of solids, liquids and gases, the particle model, density calculations, the density required practical and changes of state.
4.3.1 Changes of State and the Particle Model exam questions
2 question packs of real past exam questions, each with its mark scheme. Do not stop after a few: answer as many as you can without notes, then mark every answer with the mark scheme. The more questions you do, the more quickly you will spot how examiners ask about each idea.
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About AQA GCSE Physics 4.3.1 Changes of State and the Particle Model
This AQA GCSE Physics section uses the particle model to explain the different densities of solids, liquids and gases and what happens when a substance changes state. It includes the equation for density and a required practical measuring the density of regular and irregular solids and liquids. It is examined on Paper 1 and is the starting point for internal energy, specific heat capacity and latent heat in 4.3.2. Examiners test density calculations with unit conversions, displacement methods and the idea that mass is conserved in changes of state.
What you need to know
- Density ρ = m / V, where ρ is density in kg/m^3, m is mass in kg and V is volume in m^3. This must be memorised. Density can also be expressed in g/cm^3.
- Particle model and density In solids the particles are closely packed in a regular arrangement; in liquids they are close but irregular; in gases they are far apart. This explains why gases have much lower densities than solids and liquids.
- Density practical: regular solids Measure mass on a balance and dimensions with a ruler or vernier callipers, calculate volume (length x width x height), then calculate density.
- Density practical: irregular solids and liquids For an irregular solid, use a displacement (eureka) can or measuring cylinder to find the volume of water displaced. For a liquid, find the mass of a known volume using a measuring cylinder on a zeroed balance.
- Changes of state Melting, freezing, boiling, evaporating, condensing and sublimating are physical changes. The material recovers its original properties if the change is reversed.
- Conservation of mass When a substance changes state, mass is conserved because the number of particles stays the same. Only the arrangement and energy of the particles change.
Common mistakes in 4.3.1 Changes of State and the Particle Model
- Using cm^3 with kg, giving mixed units. Keep units consistent: g with cm^3, or kg with m^3. 1 g/cm^3 = 1000 kg/m^3.
- Saying particles in a solid do not move. They vibrate about fixed positions.
- Calling a change of state a chemical change. It is a physical change and is reversible.
- Saying particles expand when a substance is heated. The particles stay the same size; the spacing between them changes.
Try three 4.3.1 Changes of State and the Particle Model exam-style questions
1. A metal block measures 2.0 cm x 3.0 cm x 5.0 cm and has a mass of 270 g. Calculate its density in g/cm^3. (3 marks)
Show the mark scheme answer
V = 2.0 x 3.0 x 5.0 = 30 cm^3; ρ = 270 / 30; = 9.0 g/cm^3.
2. Describe how to measure the density of an irregularly shaped stone. (4 marks)
Show the mark scheme answer
Measure the mass of the stone on a balance; fill a displacement can with water to the spout; lower the stone in and collect the displaced water in a measuring cylinder; volume of water = volume of stone; density = mass / volume.
3. Use the particle model to explain why gases have a lower density than solids. (2 marks)
Show the mark scheme answer
Particles in a gas are much further apart than in a solid; so there is less mass in the same volume.
4.3.1 Changes of State and the Particle Model FAQs
What does AQA GCSE Physics 4.3.1 Changes of state and the particle model cover?
It covers density and the particle model of solids, liquids and gases, the density required practical, and changes of state including conservation of mass.
Which paper is the particle model examined in?
The Particle Model of Matter topic is on AQA GCSE Physics Paper 1.
What do I need to know for the density required practical?
Know how to find the volume of regular solids by measurement, irregular solids by displacement, and liquids using a measuring cylinder, then calculate density with ρ = m / V.
