AQA GCSE Combined Science: Trilogy Physics Paper 1 (Foundation), 2023: Question 3

14 marks · Standard Demand difficulty · Short Answer

Calculate energy changes and analyze particle behavior during the heating and melting of steel, including specific heat capacity and latent heat calculations.

Practise this question

Question

A multi-part exam question about the physics of heating and melting steel. It starts with a calculation for thermal energy change given mass, specific heat capacity, and temperature change. It follows with multiple-choice questions about the definition of internal energy, particle arrangements in solids, and the conservation of mass during melting. A diagrammatic question asks to identify the change in particle arrangement from solid to liquid. A table is provided showing carbon content in different steel types (low, medium, high carbon) per 1.0 kg, requiring a calculation to identify a 4.0 kg sample. The final part asks for a specific latent heat of fusion calculation.
Question text

03 A piece of steel is heated until it has all melted.

03.1 Calculate the change in thermal energy when the temperature of the piece of steel is

increased by 50 °C.

mass of steel = 4.0 kg

specific heat capacity of steel = 420 J/kg °C

Use the equation:

change in thermal energy = mass × specific heat capacity × temperature change

[2 marks]

Change in thermal energy = J

03.2 The internal energy of the steel increases as the steel is heated.

What is meant by ‘internal energy of the steel’?

[1 mark]

Tick ( ) one box.

The change in energy of the steel particles as the steel melts.

The energy added to the steel particles as they are heated.

The total kinetic energy and potential energy of the steel particles.13

03.3 Solid steel cannot be poured.

Which statement about the particles in a solid gives the reason why?

[1 mark]

Tick ( ) one box.

The number of particles always stays the same.

The particles are close together.

*12* The particles are in fixed positions.

The particles have a fixed size.

03.4 Complete the sentence.

Choose the answer from the box.

[1 mark]

decreases stays the same increases

As the piece of solid steel melts, the mass of the steel .

03.5 Which diagram shows how the arrangement of particles changes when a solid melts

and becomes a liquid?

[1 mark]

Tick ( ) one box.

03.6 The density of steel decreases as it melts.

How does the spacing of the particles change as the steel melts?

[1 mark]

03.7 Complete the sentence.

Choose the answer from the box.

[1 mark]

chemical permanent physical

Melting is an example of a change.

03.8 Steel is a mixture of iron and a small amount of carbon.

Table 1 shows the mass of carbon in 1.0 kg of different types of steel.

Table 1

Type of steel Mass of carbon in 1.0 kg of steel

Low carbon 2.0 g

Medium carbon 4.5 g

High carbon 7.0 g

A 4.0 kg piece of steel contains 18 grams of carbon.

Determine which type of steel the 4.0 kg piece is made from.

You should include a calculation in your answer.

[3 marks]

Type of steel16

03.9 The 4.0 kg piece of solid steel was heated until it reached its melting point.

The additional energy required to melt the piece of steel was 280 000 J.

*15* Calculate the specific latent heat of fusion of the steel.

Use the Physics Equations Sheet.

[3 marks]

Specific latent heat of fusion of steel = J/kg

Mark scheme

Show the mark scheme The mark scheme for question 3, totaling 14 marks. It provides the calculation steps and final answers: 84,000 J for thermal energy; 'total kinetic and potential energy' for internal energy; 'particles are in fixed positions' for solids; 'stays the same' for mass during melting; a diagram showing particles moving from a regular grid to a slightly more disordered but still close arrangement; 'spacing increases' for density decrease; 'physical' for the type of change. For the steel type, it shows the calculation 18 / 4.0 = 4.5 g/kg to identify 'medium carbon'. The latent heat calculation results in 70,000 J/kg.

Question 3

AO /

Question Answers Extra information Mark

Spec. Ref.

03.1 ΔE = 4.0 × 420 × 50 1 AO2

6.1.1.3

ΔE = 84 000 (J) 1 6.3.2.2

AO /

Spec. Ref.

03.2 the total kinetic energy and 1 AO1

potential energy of the steel 6.3.2.1

particles

AO /

Spec. Ref.

03.3 the particles are in fixed 1 AO1

positions 6.3.1.1

AO /

Spec. Ref.

03.4 stays the same 1 AO1

6.3.1.2

AO /

Spec. Ref.

03.5 1 AO1

6.3.1.1

– OMBINED SCIENCE: TRILOGY – 1F –

AO /

Spec. Ref.

03.6 (the space between the allow the particles move further 1 AO1

particles) increases apart 6.3.1.1

AO /

Spec. Ref.

03.7 physical 1 AO1

6.3.1.2

AO /

Spec. Ref.

03.8 mass per kg = 1 AO3

4.0

6.3.1.1

mass per kg = 4.5 g 1

medium carbon dependent on MP2 1

OR

mass in 4.0 kg of medium allow mass in 4.0 kg of low

carbon steel = 4.5 × 4.0 (1) carbon steel = 8 (g)

allow mass in 4.0 kg of high

carbon steel = 28 (g)

mass in 4.0 kg of medium dependent on MP1

carbon steel = 18 g (1)

medium carbon (1) dependent on MP2

AO /

Spec. Ref.

03.9 280 000 = 4.0 × L 1 AO2

6.3.2.3

280 000

L = 1

4.0

L = 70 000 (J/kg) 1

Total Question 3 14

How to answer it

Energy Changes and the Particle Model

What this question tests

This question assesses your understanding of the Particle Model of Matter and Energy Transfers. Key skills include calculating Specific Heat Capacity and Specific Latent Heat, defining internal energy, and using proportional reasoning to identify materials based on their composition.

Part 3.1

Calculating Thermal Energy Change

📐 Step-by-Step Calculation

  1. Identify the values: Mass (m) = 4.0 kg, SHC (c) = 420 J/kg °C, Temp change (Δθ) = 50 °C.
  2. Substitute into the formula: ΔE = 4.0 × 420 × 50
  3. Calculate: 84,000

✅ Correct Answer

84,000 J

1 mark for correct substitution
1 mark for correct answer
Parts 3.2 & 3.3

Internal Energy and Solids

💡 Key Knowledge

  • Internal Energy: The sum of the total kinetic energy (due to motion) and potential energy (due to positions/bonds) of all the particles in a system.
  • Solids: Particles are held in fixed positions by strong forces of attraction. They vibrate but cannot move past each other.

✅ Correct Choices

  • 3.2: The total kinetic energy and potential energy of the steel particles.
  • 3.3: The particles are in fixed positions.
Parts 3.4, 3.5 & 3.6

Changes of State (Melting)

🧠 Exam Technique

When a substance changes state (e.g., melting), the mass stays the same because the number of particles doesn't change. This is called "Conservation of Mass".

❌ Common Errors

Students often think particles get "bigger" or "heavier" when heated. They don't! Only the spacing and arrangement change.

✅ Correct Answers

  • 3.4: Mass stays the same.
  • 3.5: The first diagram (Regular rows of circles → Randomly arranged circles that are still touching).
  • 3.6: The spacing increases (particles move further apart).
Part 3.7 & 3.8

Physical Changes and Proportions

💡 Physical vs Chemical

Melting is a physical change because no new substance is made, and the process can be reversed by cooling (freezing).

📐 Step-by-Step: Identifying the Steel

We need to find how much carbon is in 1.0 kg of this specific steel to compare it to Table 1.

  1. Total Carbon: 18 g
  2. Total Mass: 4.0 kg
  3. Calculation: 18 g ÷ 4.0 kg = 4.5 g per kg
  4. Comparison: Table 1 shows 4.5 g per kg is Medium carbon steel.
1 mark for dividing 18 by 4
1 mark for 4.5 (g)
1 mark for "Medium carbon"
Part 3.9

Specific Latent Heat of Fusion

🧠 Using the Equation Sheet

The formula for state change is: Energy = mass × specific latent heat (E = m L).

To find L, rearrange to: L = E ÷ m

📐 Calculation

  1. Substitute: 280,000 = 4.0 × L
  2. Rearrange: L = 280,000 ÷ 4.0
  3. Final Answer: 70,000 J/kg

❌ Calculation Traps

  • Wrong Formula: Don't use the SHC formula (with temperature) for melting. Melting happens at a constant temperature, so use Latent Heat.
  • Units: Ensure the answer is in J/kg. If the energy was in kJ, you would need to multiply by 1000 first!

Topics

Physics · Chemistry · P1: Energy · P3: Particle Model of Matter · C1: Atomic Structure and the Periodic Table

Question and mark scheme from the AQA GCSE Combined Science: Trilogy examination, Physics Paper 1 (Foundation), 2023. QuestionVault is an independent revision resource; questions remain the copyright of the awarding body.