Specific Heat Capacity + Latent heat

Question 1

Define specific heat capacity

Answer 1

The specific heat capacity is the energy required to increase the temperature of 1kg of a substance by 1°C

Question 2

What is the equation for specific heat capacity in words

Answer 2

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

Question 3

What is the equation for specific heat capacity in symbols

Answer 3

∆ E = m x c x ∆ θ

Question 4

What are the units for
change in thermal Energy:
Mass
Specific heat capacity
Change in temperature

Answer 4

change in thermal Energy - Joules, J
Mass, kg
Specific heat capacity, J/kg °C
Change in temperature , °C

Question 5

Describe the method for measuring specific heat capacity

Answer 5

1) Set up the aparatus and record the initial temperature
2)Switch on the joulemeter, and then switch on the power supply
3)Allow the experiment to run for 6 minutes, then switch off the power supply and record the reading on the joule meter
4)Wait for a few minutes until the temperature gets to it’s highest value, record this value
5) Substitute numbers into the equation and calculate the specific heat capacity

Question 6

Draw and label diagram showing the method for measuring specific heat capacity

Answer 6

file:///C:/Users/44748/Documents/measuring%20specific%20heat%20capacity,%20latent%20heat%20and%20density.pdf

Question 7

Give an evaluation of experiment
Explain why the increase in temperature of the metal block is lower than the expected increase in temperature

Answer 7

Part of the heater is not in the metal block therefore it’s energy goes into the surroundings, instead of heating the block

Some the heat energy will be lost from the metal block through the insulation

Question 8

In the experiment what does ‘E’ in C=E/m x change in temp represent

Answer 8

E is the measure on the joulemeter - this is how much energy is going to the heater

Question 9

The experiment for specific heat capacity does not give the correct value for the specific heat of copper. Suggest one reason why

Answer 9

The experiment does not give the correct value for the specific heat of copper as heat energy was lost to the surroundings.
Energy was needed to warm the heater.

Question 10

Explain why the value for specific heat capacity is higher than it should be

Answer 10

The value for E (energy) was higher than it should be due to energy loss therefore the value for specific heat capacity should be lower.

Question 11

Metal Specific heat capacity in J/kg°C
Aluminium 900
Iron 450
Lead 130

Which one of the metals will heat up the most.
Give, in terms of the amount of energy needed to heat the metal blocks, a reason for your answer

Answer 11

Lead.
Lead has the lowest specific heat capacity meaning it needs least energy to raise it’s temperature by 1°C

Question 12

Define latent heat

Answer 12

Latent heat is the energy required to change the state of 1kg of a substance with no change in temperature

Question 13

Word equation for latent heat

Answer 13

energy for a change of state = mass × specific latent heat

Question 14

symbol equation for latent heat

Answer 14

E = m x L

Question 15

Units for
Energy for a change of state
Mass
Specific latent heat

Answer 15

Energy for a change of state - Joules, J
Mass , Kg
Specific latent heat - J/kg

Question 16

What is specific latent heat of fusion

Answer 16

Change of state from solid to liquid (or vice versa)

Question 17

What is Specific latent heat of vaporisation

Answer 17

– change of state from liquid to vapour (or vice versa)

Question 18

Equation for latent heat of fusion /WORD AND SYMBOL + units

Answer 18

Energy = mass x latent heat of fusion
E = m x Lf (subscript f)

Energy = J
mass = Kg
Latent heat of fusion - J/kg

Question 19

Equation for latent heat of vaporisation/WORD AND SYMBOL + units

Answer 19

Energy = mass x latent heat of vaporisation
E = m x Lv (subscript v)

Energy = J
mass = Kg
Latent heat of vaporisation - J/kg

Question 20

In terms of cooling, what is the specific latent heat

Answer 20

For cooling, specific latent heat is the energy released by a change in state.

Question 21

Draw and label diagram showing the method for measuring specific latent heat of fusion of water

Answer 21

file:///C:/Users/44748/Documents/measuring%20specific%20heat%20capacity,%20latent%20heat%20and%20density.pdf

Question 22

Describe the method for measuring specific latent heat of fusion of water

Answer 22

1) At the start of the experiment, both beakers are empty.
2) The heater is then switched on and the experiment for several minutes
3) After several minutes, turn off the heater and record he reading on the joulemeter and the mass of water in both beakers.

Question 23

Calculate the specific latent heat of fusion of water
using the experiment

The energy from the joule meter = 7100J
mass of water in Control beaker = 50g
mass of water in beaker with heater = 70g

Answer 23

E = 7100J
m=0.07kg - 0.02kg = 0.02
Lf=?

E = m x Lf (subscript f)
7100 = 0.02 x Lf
Lf = 7100/0.02
Lf = 355,000 J/kg

Question 24

When measuring the latent heat of fusion of water why is there a control experiment running

Answer 24

The control experiment is set up to measure the mass of the ice that has melted due to room temperature.

Question 25

Explain why the value for the specific latent heat of fusion of water is lower than it should be

Answer 25

The value calculated is higher than the actual value become some of the energy has dissipated from the heater to the surroundings. Therefore the energy reading should be lower, hence the value for the specific latent heat of fusion of water should be lower