## Examples

1. Calculate the amount of heat needed to increase the temperature of 250g of water from 20oC to 56oC.

q = m x Cg x (Tf - Ti)
m = 250g
Cg = 4.18 J oC-1 g-1 (from table above)
Tf = 56oC
Ti = 20oC

q = 250 x 4.18 x (56 - 20)
q = 250 x 4.18 x 36
q = 37 620 J = 38 kJ

2. Calculate the specific heat capacity of copper given that 204.75 J of energy raises the temperature of 15g of copper from 25o to 60o.

q = m x Cg x (Tf - Ti)
q = 204.75 J
m = 15g
Ti = 25oC
Tf = 60oC

204.75 = 15 x Cg x (60 - 25)
204.75 = 15 x Cg x 35
204.75 = 525 x Cg
Cg = 204.75 ÷ 204.75 = 0.39 JoC-1 g-1

3. 216 J of energy is required to raise the temperature of aluminium from 15o to 35oC. Calculate the mass of aluminium.
(Specific Heat Capacity of aluminium is 0.90 JoC-1g-1).

q = m x Cg x (Tf - Ti)
q = 216 J
Cg = 0.90 JoC-1g-1
Ti = 15oC
Tf = 35oC

216 = m x 0.90 x (35 - 15)
216 = m x 0.90 x 20
216 = m x 18
m = 216 ÷ 18 = 12g

4. The initial temperature of 150g of ethanol was 22oC. What will be the final temperature of the ethanol if 3240 J was needed to raise the temperature of the ethanol?
(Specific heat capacity of ethanol is 2.44 JoC-1g-1).

q = m x Cg x (Tf - Ti)
q = 3240 J
m = 150g
Cg = 2.44 JoC-1g-1
Ti = 22oC

3240 = 150 x 2.44 x (Tf - 22)
3240 = 366 (Tf - 22)
8.85 = Tf - 22
Tf = 30.9oC

#### 1 comment:

1. thank you so much for this it really helped