Measuring enthalpy changes

Question 1

what is the formula for specific heat capacity ?

Answer 1

Q = m x c x ∆T
m = mass of the surroundings generally water
c = specific heat capacity
∆T = temperature change

Question 2

deifine specific heat capacity

Answer 2

amount of energy required to raise 1g of water by 1 kelvin

Question 3

what is the specific heat capacity of water ?

Answer 3

4.18 Jg-1 K-1

Question 4

Describe equipment for coffee cup calorimetry?

Answer 4

• has polystyrene lid: to provide insulation and minimize heat loss
• thermometer: measures temp. change
• styrofoam cup: held in another styrofoam cup or beaker to provide further insulation

Question 5

give three sources of error that affect the value of energy transferred

Answer 5

1. heat energy is lost to its surroundings - copper can, thermometer and air
2. not complete combustion so the flame is yellow and not roaring blue

Question 6

what precautions do we take to prevent heat loss to the surroundings when we do this experiment in the lab ?

Answer 6

1. put a lid on copper can
   2.use draft excluders
2. copper calorimeter