Course: Combined Science + Separate Physics | Tier: Foundation | Linked: Specific heat capacity practical
✏️ You need: your exercise book and a calculator. Write out every step before you open the answer.
📌 KEY DEFINITIONS – learn them word for word
Specific heat capacity: the amount of energy needed to raise the temperature of 1 kg of a substance by 1 °C.
Energy = mass × specific heat capacity × temperature change
Unit of specific heat capacity: J/kg °C (joules per kilogram per degree Celsius).
🎬 Watch first: Free Science Lessons videos
Video 1: what specific heat capacity means and how to use the equation. Pause it and copy the equation into your book.
Video 2 (optional): the required practical – how to measure specific heat capacity in the lab.
📖 Notes
What does it mean?
Some materials heat up quickly. Others heat up slowly. Specific heat capacity tells you how much energy a material needs to warm up.
- High specific heat capacity → needs lots of energy → heats up slowly 🐢
- Low specific heat capacity → needs little energy → heats up quickly 🐇
🏖️ Real life: on a sunny day, the sand on a beach gets hot quickly but the sea stays cool. Water has a much higher specific heat capacity than sand.
| Material | Specific heat capacity (J/kg °C) | Heats up… |
|---|---|---|
| 💧 Water | 4200 | very slowly |
| 🥫 Aluminium | 900 | quicker |
| 🔩 Iron | 450 | quicker still |
| 🟠 Copper | 385 | very quickly |
What does 4200 J/kg °C mean? It takes 4200 J of energy to warm 1 kg of water by 1 °C. That is why water is used in radiators and hot water bottles – it stores lots of energy.
🧮 How to calculate energy – 3 steps
Step 1 – Temperature change = end temperature − start temperature
(Always take the smaller number from the bigger number.)
Step 2 – Check the mass is in kg. If it is in grams, divide by 1000. (500 g = 0.5 kg)
Step 3 – Multiply: energy = mass × specific heat capacity × temperature change
Write the unit: J (joules)
✅ Worked example
A pan contains 2 kg of water at 20 °C. It is heated to 30 °C. Specific heat capacity of water = 4200 J/kg °C. How much energy is needed?
Step 1: Temperature change = 30 − 20 = 10 °C
Step 2: Mass = 2 kg ✔
Step 3: Energy = 2 × 4200 × 10 = 84 000 J
🔍 See the specific heat capacity equation
✏️ Questions
Level 1: What does it mean?
Q1 1 kg of water and 1 kg of copper are heated in the same way. Which one warms up faster? Use the table to explain.
Show answer
Copper. It has a lower specific heat capacity (385 J/kg °C), so it needs less energy to warm up.
Q2 A cup of tea cools from 80 °C to 50 °C. What is the temperature change?
Show answer
80 − 50 = 30 °C
Level 2: Everything given
Q3 💧 1 kg of water is heated. Its temperature goes up by 10 °C. How much energy is needed? (water = 4200 J/kg °C)
Show answer
Energy = 1 × 4200 × 10 = 42 000 J
Q4 🥫 A 2 kg aluminium block is heated. Its temperature goes up by 5 °C. How much energy is needed? (aluminium = 900 J/kg °C)
Show answer
Energy = 2 × 900 × 5 = 9000 J
Q5 🔩 A 4 kg iron pan is heated. Its temperature goes up by 50 °C. How much energy is needed? (iron = 450 J/kg °C)
Show answer
Energy = 4 × 450 × 50 = 90 000 J
Level 3: Find the temperature change first
Q6 ☕ A kettle heats 1 kg of water from 20 °C to 100 °C. How much energy is needed? (water = 4200 J/kg °C)
Show answer
Temperature change = 100 − 20 = 80 °C
Energy = 1 × 4200 × 80 = 336 000 J
Q7 🟠 A 2 kg copper block warms from 20 °C to 30 °C. How much energy does it gain? (copper = 385 J/kg °C)
Show answer
Temperature change = 30 − 20 = 10 °C
Energy = 2 × 385 × 10 = 7700 J
Q8 🍵 500 g of hot water cools from 80 °C to 30 °C. How much energy does it give out? (water = 4200 J/kg °C)
Hint: change grams to kg first.
Show answer
Mass = 500 ÷ 1000 = 0.5 kg
Temperature change = 80 − 30 = 50 °C
Energy = 0.5 × 4200 × 50 = 105 000 J
Level 4: Challenge – work backwards
Tip: multiply together the numbers you know, then divide the energy by that answer.
Q9 💧 21 000 J of energy is given to 1 kg of water. By how much does its temperature go up? (water = 4200 J/kg °C)
Show answer
Mass × specific heat capacity = 1 × 4200 = 4200
Temperature change = 21 000 ÷ 4200 = 5 °C
Q10 🧪 A student gives 1800 J of energy to a 1 kg metal block. Its temperature goes up by 2 °C. Calculate the specific heat capacity. Use the table to name the metal.
Show answer
Mass × temperature change = 1 × 2 = 2
Specific heat capacity = 1800 ÷ 2 = 900 J/kg °C
The metal is aluminium.
Q11 🛁 84 000 J of energy warms some water by 10 °C. What is the mass of the water? (water = 4200 J/kg °C)
Show answer
Specific heat capacity × temperature change = 4200 × 10 = 42 000
Mass = 84 000 ÷ 42 000 = 2 kg
Level 5: Explain it
Q12 🌡️ Central heating radiators are filled with water. Explain why water is a good choice.
Show answer
Water has a high specific heat capacity, so it can store a lot of energy. It gives out energy to the room for a long time as it cools.
⚠️ Where students lose marks
- Using the final temperature instead of the temperature change. Always subtract first.
- Forgetting to change grams to kg. Divide by 1000.
- Mixing up high and low: a high specific heat capacity means it heats up slowly.
- Missing the unit: energy is in J; specific heat capacity is in J/kg °C.
Next: More specific heat capacity questions · Specific heat capacity practical · Energy topic page
