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2.2.3Thermal Physics

Investigating Specific Heat Capacity — Cambridge IGCSE Physics 0625 Revision Notes & Topical Questions

5 min read 10 parts Lesson 19 of 45 1 quiz

📚 Cambridge IGCSE Physics 0625 Hub / Topical Revision
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Lesson summary

2.2.3 Investigating Specific Heat Capacity — IGCSE PHYSICS notes: Describe and evaluate an electrical-heater experiment to find the specific heat capacity of a solid or a liquid.Aim — determine c by linking the electrical energy supplied to the temperature rise and thermal energy…

  • Independent variable
  • Control variables
  • Temperature change
  • Results table
  • Zero the balance
  • Thermometer

Part 1 of 8Aim and variables

Aim
  • Aim determine c by linking the electrical energy supplied to the temperature rise and thermal energy stored
Independent variable
  • Independent variable time
Dependent variable
  • Dependent variable temperature
Control variables
  • Control variables current and potential difference supplied

Part 2 of 8Equipment

EquipmentPurpose
ThermometerMeasure temperature change of the solid or water
Aluminium block or beaker of waterThe material investigated
Immersion heaterHeat the block or water
VoltmeterMeasure voltage across the heater
AmmeterMeasure current through the heater
Power supplySupply power to the heater
Digital balanceMeasure mass
StopwatchTime the heating

Part 3 of 8Method for water

1
Place the beaker on the balance, press zero, add about 250 cm³ of water and record its mass.
2
Place the immersion heater and thermometer in the water.
3
Connect the ammeter in series with the supply and heater, and the voltmeter in parallel with the heater.
4
Use a direct current supply so readings stay steady.
5
Record the initial temperature at time 0 s.
6
Switch on at about 10 V and start the stopwatch.
7
Record voltage, current and temperature every 60 s for 10 minutes.

Part 4 of 8Method for the aluminium block

1
Record the mass of the block.
2
Put the thermometer in one hole and the heater in the other.
3
Connect the circuit as for water.
4
Record the initial temperature, switch on at about 10 V and start the stopwatch.
5
Record voltage, current and temperature every 60 s for 10 minutes.

Part 5 of 8Analysis

Energy supplied
  • E = IVt using average current and voltage and the time spent heating
Temperature change
  • Δθ = final temperature − initial temperature
Specific heat capacity
  • Specific heat capacity c = E ÷ (mΔθ) with mass in kg
Results table
  • Results table columns for time, voltage, current, temperature, energy supplied and temperature change

Part 6 of 8Errors and improvements

Zero the balance
  • Zero the balance before measuring mass
Thermometer
  • Thermometer keep it off the sides and base of the beaker so it reads the liquid
Final reading
  • Final reading wait for the temperature to stop rising after switching off
Evaporation
  • Evaporation some water is lost, so use an average of the mass before and after
Heat loss
  • Heat loss makes measured c too high
  • Wrap the beaker
  • Use a lid
  • Heat for a shorter time
Stirring
  • Stirring stir constantly so the temperature measured is the temperature throughout the liquid
Random error
  • Random error when readings flicker between two values, be consistent in choosing the higher one

Part 7 of 8Safety

Immersion heater
  • Immersion heater very hot, so do not touch it and have a heatproof mat ready
Unstable beaker
  • Unstable beaker use a clamp stand to hold the heater and thermometer
Eye protection
  • Eye protection wear goggles while heating water
Standing
  • Standing stand throughout to react quickly to spills

Part 8 of 8More from the specification

1
Calorimetric thermal system
  • Calorimetric thermal system insulating the metal block minimizes unwanted thermal energy dissipation from the experimental calorimeter system to surroundings.
2
Specific Heat Capacity Equation
  • The thermal energy ΔE transferred to heat a substance of mass m without a change of state is given by ΔE = m c ΔT,
  • where c is specific heat capacity in J/(kg °C).
3
Microscopic Thermal Expansion
  • Absorbing thermal energy increases the average kinetic energy and vibrational speed of particles,
    • (atoms or molecules)
  • causing thermal expansion as intermolecular separation increases.
4
Phase Changes at Melting and Boiling Points
  • During melting and boiling, transferred energy is used to overcome intermolecular binding forces rather than raising particle kinetic energy, maintaining a constant temperature.
5
Experimental Measurement of Heat Capacity
  • In a laboratory experiment, electrical work transferred by an immersion heater (E = I V t) is measured alongside temperature rise, using insulation to minimize energy losses to surroundings.
6
Specific Heat Capacity Equation
  • The thermal energy ΔE transferred to heat a substance of mass m without a change of state is given by ΔE = m c ΔT,
  • where c is specific heat capacity in J/(kg °C).
7
Microscopic Thermal Expansion
  • Absorbing thermal energy increases the average kinetic energy and vibrational speed of particles,
    • (atoms or molecules)
  • causing thermal expansion as intermolecular separation increases.
8
Phase Changes at Melting and Boiling Points
  • During melting and boiling, transferred energy is used to overcome intermolecular binding forces rather than raising particle kinetic energy, maintaining a constant temperature.
9
Experimental Measurement of Heat Capacity
  • In a laboratory experiment, electrical work transferred by an immersion heater (E = I V t) is measured alongside temperature rise, using insulation to minimize energy losses to surroundings.
10
Internal energy
  • Total random kinetic and potential energy of all particles.
11
Intermolecular force
  • An attractive force between particles.
12
Boiling
  • Liquid becoming gas throughout the liquid at the boiling point
13
Molecule
  • Tiny particle of the fluid, too small to be seen.
14
Expansion
  • Increase in size on heating as particles move further apart.
15
Melting
  • Change from solid to liquid.
16
Force
  • A push or pull measured in newtons.
17
Joule
  • Unit of energy, 1 kg·m2/s2.
18
Kinetic energy
  • K = ½mv2, energy of motion.
19
Energy transferred
  • W = V Q, in joules.
    What the symbols mean: E or W = energy transferred (J) · Q = charge (C) · V = potential difference (V) · I = current (A) · t = time (s)
20
ΔE
ΔE mcΔθ [1 mark]
What the symbols mean: E, Q or q = energy transferred (J) · m = mass (kg; g in chemistry calorimetry) · c = specific heat capacity (J kg−1 °C−1; water 4.18 J g−1 °C−1) · ΔT or Δθ = temperature change (°C or K)

Key terms

TermMeaning
Specific heat capacityEnergy required per unit mass per unit temperature increase
Immersion heaterElectric heater placed in a liquid or block to supply energy
Independent variableThe variable deliberately changed, here time
Dependent variableThe variable measured, here temperature
Control variableA quantity kept the same to make the test fair

Avoid these mistakes

1
Leaving mass in grams — convert to kilograms before calculating c.
2
Blaming vague human error — name a specific cause such as heat loss to the surroundings.
3
Using AC from the supply — a direct current keeps current and voltage readings steady.
4
Taking the final temperature the moment the heater is switched off — wait for the highest value.

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