Qualitative

Question 1

Step 2 and 1 mark?

Answer 1

Determine:
1) θm - θ2 = fall in temp. of the mass.

2) θ2 - θ1 = rise in temp. of water

3) thermal energy gained by cold water:
E=mc(θ2-θ1)
IN JOULES (J)
1 mark for correct power of ten and units.

Question 2

Step 3 and marks?

Answer 2

1) record for a temp between 60-70C.
2) put the data into a table, headings:
θm, θ1, θ2, θm-θ2, θ2-θ1, E

All θ put in degrees Celsius (C), E in Joules (J)

2 marks - repeating at diff. temperature and suitable table and all data.

Question 3

Explain experiment step 1 and 2 marks?

Answer 3

1) measure and record θ1 (cold water) in degrees Celsius.
2) put 0.1kg mass into half full beaker of hot water (>75C) for 30secs then measure the temperature of water=mass temp(θm).
3) retrieve mass, put into 0.07kg cold water, record max temp. of cold water (θ2).

2 marks for safe+correct set up and correct temp of θm.

Question 4

Step 4 and mark?

Answer 4

Identify a hazard and describe a precaution for safety: (1mark)

Don’t splash the hot water with the mass when putting it in the water because you might burn yourself, instead lower it in slowly.

Question 5

Step 5 and mark?

Answer 5

Assume:
Energy gain by water = energy loss by metal

Then find the specific heat capacity of the metal (Cm) at both temperatures (Jkg^-1C^-1)
1 mark

Question 6

What aren’t values of Cm the same? 3 marks

Answer 6

1) there will be energy losses to the beaker - when the mass is put into the cold water the cold water warms up, thus heating up the beaker and losing energy. When the metal has a higher original temperature θm, more energy will be lost to the beaker once it enters the cold water since it will take longer for the mass and the water to reach thermal equilibrium.
2) assuming the metal has reached thermal eq. in 30 seconds. If it hasn’t reached TE it means that the value of θm is inaccurate since the metal won’t have reached the same temperature as the hot water. This will cause a difference in calculated values of θm for the two experiments since in 30seconds, the metal mass will reach closer to the 75C temperature, causing the final value for Cm1 to be different to that of Cm2.
3) also assuming the metal is the same temperature throughout. However it may not be, meaning the thermal energy stored in the 0.1kg mass is less since the centre might be colder than the outside. This will cause a disparity in the values of Cm because exp. for Cm2 is likely to heat more thoroughly than exp. for Cm1 since number 2 doesn’t have to heat to such a high temperature in the same time period.