RP specific heat capacity

Question 1

specific heat capacity

Answer 1

the amount of energy required to raise the temperature of 1 kg of a substance by 1 °C

Question 2

equation + units

Answer 2

change in thermal energy = mass x specific heat capacity x change in temperature
ΔE = mcΔθ
J kg J/kg°C °C

Question 3

what two stores is internal energy comprised of?

Answer 3

potential and kinetic

Question 4

what is temperature?

Answer 4

the average kinetic energy of the particles in a substance

Question 5

equipment list

Answer 5

-copper, iron and aluminium metal blocks with two holes
-insulation
-thermometer
-pipette
-heater
-12V power supply
-balance

Question 6

method

Answer 6

1. measure and record the mass of the copper block
2. wrap insulation around the block and connect the heater and power pack
3. use a pipette to put a small amount of water into the other wall then place in the thermometer
4. if power of heater is unknown, connect a voltmeter and ammeter then switch on the power pack and calculate power
5. start the timer and measure the temperature of the block every minute for ten minutes
6. repeat for different metal blocks

Question 7

calculating the specific heat capacity from a graph

Answer 7

1/gradient

Question 8

safety

Answer 8

-don’t handle block or heater while heating
-keep block on heatproof
-keep careful of spillages around power pack

Question 9

how can you calculate the power of the heater?

Answer 9

connecting it in parallel with a voltmeter, and in series with an ammeter then using P=VI

Question 10

why do the metal blocks have two holes?

Answer 10

one for heater, one for thermometer

Question 11

what can be done to improve the reading off the thermometer?

Answer 11

add a few drops of water in the hole with the thermometer to improve the thermal contact

Question 12

what graph do you plot?

Answer 12

temperature against energy transferred (work done) by the heater

Question 13

how could you calculate work done by the heater?

Answer 13

E=Pt

Question 14

describe the graph once the heater has warmed up

Answer 14

a straight line

Question 15

why should you wrap insulator around the block?

Answer 15

to reduce heat lost to the environment and ensure temp reading is as accurate as possible

Question 16

difference between heat capacity and specific heat capacity

Answer 16

specific heat capacity is the heat capacity measured for a mass of 1kg

Question 17

why might the graph not be linear?

Answer 17

there will initially be some thermal inertia whilst the block and heater warm up

Question 18

what does the gradient represent?

Answer 18

the inverse of the heat capacity for the metal block

Question 19

what causes the temperature to increase?

Answer 19

-current does work on heater when power pack is turned on
-by transferring energy electrically from power supply to heater’s thermal energy store
-this energy is then transferred to material’s thermal energy store by heating

Question 20

variables

Answer 20

independent-metal block
dependent-temperature
control-power supply, power of heater