1. Today’s lesson Demonstrate understanding of the term thermal capacity
Describe an experiment to measure the specific heat capacity of a substance
Recall and use the equation:
Energy = mass x specific heat capacity x change in temperature

2. Imagine…
Heating a 1 kg block of copper and a 1 kg block of brass for the same time. Would their temperature rise be the same?
copper
brass

3. Why are the temperature rises different?
When a substance is heated, its internal energy increases (potential and kinetic). The stronger the force between the particles in the substance, the more heat energy goes into potential energy (and less into kinetic), so the temperature rise is less than in substances with little force between particles.
(Remember temperature is a measure of the kinetic energy)

4. Specific heat capacity
Specific heat capacity is the amount of energy needed to raise the temperature of one kilogram of a substance by 1°C
Specific heat capacity of water = 4186 J/kg/°C
Specific heat capacity of kerosene = 2010 J/kg/°C
Specific heat capacity of mercury = 140 J/kg/°C
Can you COPY this please?

5. Calculations using S.H.C.
Energy absorbed = Mass x Specific Heat capacity x Temp rise
E = mcΔT J kg
J/kg/°C °C
Can you COPY this too please?

6. For example
0.5 kg of olive oil is heated until its temperature rises by 120 °C. If the specific heat capacity of olive oil is 1970 J/kg/°C, how much heat energy was used?
Energy absorbed = Mass x Specific Heat capacity x Temp rise
Energy absorbed = 0.5 x 1970 x 120
Energy absorbed = J

7. An analogy: Water and wetness
“This analogy is one of my ideas!”
Richard Feynmann – Nobel prize winning Physicist, lock-picker and bongo player

8. Two towels – same size/mass
You can add the same amount of water (heat), but the cheap towel will be “wetter”
You can add the same amount of water (heat), but the cheaper towel will be “wetter” (temperature). They have different capacities for absorbing water

9. Questions

10. Investigation time!
Let’s do an experiment to measure specific heat capacities
solid block
immersion heater
thermometer

11. Measuring SHCs Energy put IN to metal = voltage x current x time
Energy = mass x specific heat capacity x temp rise
voltage x current x time = mass x specific heat capacity x temp rise
Specific heat capacity = (voltage x current x time)/(mass x temp rise)

12. The answers! Aluminium 897 J/kg/°C Copper 385J/kg/°C Steel 380 J/kg/°C
Brass 377 J/kg/°C

13. Let’s try some questions!
“What would Richard Feynmann do?” If you read biographies it is very true!
Let’s try some questions!