Req Practical 1 Specific Heat Capacity Flashcards
Define the ‘Specific heat capacity’ of a substance
The amount of energy needed to raise the temperature of 1kg of a substance by 1 degree Celsius
State the units for Specific Heat Capacity
J/°C/kg
Joules/Degree Celsius/Kilogram
State the equation used to calculate the temperature change shen a subatance is heated . Give appropriate units
• change in thermal energy = mass x specific heat capcity x temp change
If the power of the heater being used isn’t given, how can you calculate it ?
By connecting it in parallel with a voltmeter, and in series with an ammeter, and then applying the equation
P = I x V
Why do the metal blocks used in the experiment have two hole in them ?
One is for the heater and one is for the thermometer
What can be done to improve the reading given by the thermometer?
Add a few drops of water in the hole with the thermometer to improve the thermal contact and ensure even heating
What reading do you record during the experiment and how frequently ?
You record the temperature value every 10 minutes from when the heater is inserted and switched on
What graph do you plot with the data ?
A graph of temperature against work done by the heater
How do you calculate work done by the heater?
Energy = Power of heater x Time
Where energy is equivalent to the work done
Once the block has initially warmed up, describe the graph of temperature against work done by the heater that should be obtained
It should be a linear relationship and so should produce a straight line
If you start timing from when you switch on the heater, why may the graph not initially be linear?
There will initially be some thermal inertia whilst the block and heater warm up
What does the gradient of the graph represent ?
The inverse of the heat capacity for the metal block
How do you obtain the specific heat capacity for the metal you are measuring ?
Divide the inverse of the gradient by the mass of the metal block used
What is the difference between heat capacity and specific heat capacity ?
Specific heat capacity is the heat capacity measured for a mass of 1kg
Why should you wrap insulation around the outside of the metal block ?
To reduce the heat loss to the environment and ensure the temperature reading is as accurate as possible
