PAG 11.2 Determine Specific Heat Capacity Flashcards
What is specific heat capacity?
The amount of energy required to raise the temperature of 1kg of substance by 1 degree
What equation can be used to calculate the energy required to change the temperature of a sample?
E = mcΔT
What is the unit of specific heat capacity?
Jkg^-1K^-1
How can the specific heat capacity of a block be obtained from a graph of energy against temperature
c = gradient/mass
How can the work done by an immersion heater in a given period of time be calculated?
E = Pt
How can the power of an immersion heater be determined?
P = IV
Immersion heater is connected in a circuit in series with an ammeter and in parallel to a voltmeter.
The readings from these meters can be multiplied together to obtain the power.
How is your value for SHC likely to differ from the true value?
Experimental is likely to be higher than the true value due to energy losses in the wiring and heat loss to the surroundings.
How can the heat lost to the surroundings be reduced?
The metal cover can be placed in an insulating cover. This will reduce the heat radiated to the surroundings.
Why should the immersion heater be in contact with the block?
The heat will be mostly transferred through conduction. This happens when the heater is in contact with the block
How can the mass of the metal block be measured?
Mass balance
Should be zeroed before placing metal block on to avoid zero error
Why should you continue to measure the temperature after the heater has been switched off?
The temperature is likely to continue increasing for a short period after the heater is switched off
When should you stop measuring the temperature of the block?
Until temperature starts to decrease.
Ensure that you record the maximum temperature that the block reaches
As well as reducing energy losses, what is another advantage of placing the metal block into the insulating cover?
Acts as a safety precaution.
The block will get very hot and so insulating it reduces the likelihood of burning yourself through contact with it.
What safety precautions should be taken when using an immersion heater?
The heater will get very hot and so you must not touch any exposed parts of it during, or immediately after use.
It should be switched off when not in use to prevent it overheating.
How can the percentage difference between your value and true value be calculated?
[Your Value - True Value]/True Value x 100
