Specific Heat Capacity

Question 1

what is internal energy

Answer 1

the sum of energy in the kinetic and potential energy stores of the particles

Question 2

if heating a substance increases the energy in its thermal energy stores, what is temperature in terms of the kinetic theory

Answer 2

a way of measuring the average internal energy of a substance

Question 3

what are some examples of different amounts of energy being needed to increase the temperature of different substances

Answer 3

• you need 4200J to warm 1kg of water by 1C

- but only 139J to warm 1kg of mercury by 1C

Question 4

what do materials that need to gain a lot of energy to warm up also do and what does it mean

Answer 4

• they lose or release a lot of energy when cooling down

- in other words, they store a lot of energy for a given change in temperature

Question 5

what is the change in the energy stored in a substance when you heat it related to

Answer 5

the change in its temperature by its specific heat capacity

Question 6

what is the specific heat capacity of a substance

Answer 6

• the change in energy in the substances thermal energy store in order to raise the temperature of 1kg of it by 1C
• basically, the amount if energy required to increase the temperature of 1kg of it by 1C

Question 7

what is the specific heat capacity of water

Answer 7

4200J/kg C

Question 8

what is the equation for calculating the change in thermal energy

Answer 8

• change in thermal energy = mass x specific heat capacity x temperature change
• change in Q = m * c * change in (theta)

Question 9

what are the units for change in thermal energy, mass, specific heat capacity and temperature change

Answer 9

• change in thermal energy = J
• mass = kg
• specific heat capacity = J/kg C
• temperature change = C

Question 10

what is the process carried out to measure the specific heat capacity of water

Answer 10

• use a mass balance to measure the mass of the insulating container
• fill the container with water and measure the mass again to find mass of water
• set up so that joulemeter reads 0 and place a lid on the container
• measure the temp of the water then turn on the power
• when the temp of that water has increased by 10C by using a thermometer to observe, stop the experiment
• record the energy on the joulemeter and the increase in temp

Question 11

how do you specifically find the mass of the water in the experiement

Answer 11

by subtracting the mass of the water in the container from the mass of the container that should have already been weighed

Question 12

how would you calculate the specific heat capacity of the water in the experiment

Answer 12

by rearranging the change in thermal energy equation above for calculating the specific heat capacity and plugging in your measurements

Question 13

why should you repeat the experiment multiple times

Answer 13

to be able to calculate an average of the specific heat capacity of water

Question 14

what other instrument could you use in the experiment and for what reason

Answer 14

• you could use a voltmeter and ammeter instead of a joulemeter
• to time how long the heater was on for then calculate the energy supplied

Question 15

what is the equation for calculating specific heat capacity

Answer 15

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