Internal Energy and Energy Transfers Flashcards
Savemyexam [Medium]
Medium
State two advantages of using digital thermometer rather than the analouge thermometer. [2]
The analouge thermometer measurement is easy to misread.[1]
The digital thermometer meausrements has higher resolution. [1]
Resolution - this means he smallest change in a quantity that can be detected by a measuring instrument.
Medium
Calculate the energy transferred to the ice as 0.25kg of ice was heated from -15C to 0C.
The specific heat capacity of ice is 2050 J/kg C [3]
Energy = mass x specific heat capacity x change in temperature.
0 –15 = 15
Energy = 0.25 x 2050 x 15
Energy = 7687.5J
Medium
After 1760 seconds the temperature of the water began to increase again.
Explain why. [2 marks]
The change from state was soild to liquid. [1]
and it is still being heated. [1]
Mistake: Misunderstood the question I thought the question said to expla
Medium
A thermosflask, as shown in Figure 3 is designed to minimise the trasnfer of thermal energy between the contents and the surroundings.
The claim is made by manufacturer is that the thermos can keep hot water warm for up to 6 hours.
14,800 J of energy are transferred from the thermos
to the surroundings in 6 hours.
The mass of water in the flask is 360g.
The specific heat capacity of water is 4200J/kg C.
The intial temperature of the water is 95 C.
Calculate the tempertaure of water in the flask after 6 hours, and state whether or not you agree with the manufacturer’s claim. [4]
Mass = 360/1000 = 0.360kg - conversion from g to kg. [1]
14,800 = 0.360x 4200x (95 - T)[1]
T= 95 - 14800/( 0.36 x 4200) [1]
T = 85 C the water in the flask is still hot after 6 hours, therfore the manufacturer’s claim is correct. [1]
Medium
By how much has the internal energy of the water in the flask changed? [ 1 mark ]
14,800 J [1]
Medium
A student wants to carry out an investigation to calculate the speciifc latent heat of fusion of water.
She uses a 250 ml beaker to hold the water.
Suggest what other apparatus she would need to carry out the investigation.
Mass balance [1]
Electric heater [1]
Jolemeter [1]
Hard
State the variables which need to be measured to calculate specific heat capacity of water.
Explain how the student should one of these variables. [4]
Mass of water [1] zero the scales with the empty cup before adding water .[1]
Energy supplied [1]use start and end readings on the joluemeter.[1]
Hard
State what the student should do with the anonymous reading while doing the experiment. [1]
Repeat the experiment to take another reading.
Hard
Describe the movement of the particle that make up the lidded beaker and the movement of particles of water vapour [2]
The particles vibrate around a fixed postion.[1]
In water vaapour, paticles move at high speed[1]
Hard
Explain what is meant by the specific heat of a substance [2]
The thermal energy needed to raise the temperature of 1kg [1]by 1 C[1]
Define and state the differences between latent heat of fusion and latent of vaporisation[3]
Remember it the latent heat of fusion can happen by melting but also fr
latent heat of fusion is the thermal energy required to change the state of 1kg of a susbatnce between a soild and a liquid with no change in temperature. [1]
Latent heat of vaporisation is the thermal energy required to change the state of a 1kg of a substance between liquid to gas with no change in temperature.[1]
Latent heat of fusion describes the change of state between soild and liquid while latent heat of vaporisation describes the change of state between liquid and gas. [1]
Hard
Give me 2 advantages of using the electric water bath rather than the bunsen burner while doing an experiment to calculate the energy transferred to the liquid. [2]
The unknown subsatnce can be flammable so the water bath is safer.[1]
It is easier to caluclate the energy input from the water bath rather than the bunsen burner as the energy input from a bunsen burner is a variable. [1]
