Chemistry Practical: Measurement of Enthalpy change on Neutralization

Results table

Volume of 1M HCL, HNO3, H2SO4 - cm3

+- 0.05 Temperature of 1M HCL - °C

+

- 0.5 °C Temperature of 1M HNO3 - °C

+- 0.5 °C Temperature of 0.5M H2SO4 - °C

+

- 0.5 °C

0. 00 3¬1.0 30.0 31.0
5. 00 32.0 31.0 33.0
10. 00 33.0 31.5 35.0
15. 00 34.0 32.0 36.0
20. 00 35.0 31.5 37.0
25. 00 36.0 31.5 38.0
30. 00 35.0 31.5 37.0
35. 00 34.0 31.5 36.0
40. 00 34.0 31.5 35.0
45. 00 33.0 31.5 35.0
50. 00 33.0 31.5 35.0

Calculations

To measure the heat of neutralization - the following formula was used:

Q = mc Ä T

Q = Energy in (joules, J)

m = density of solution = density of water

(assumption: 1 ml = 1grammes because of density).

c = specific heat capacity ( Jg-1°C-1), the energy required to raise the temperature of 1g of a substance by 1°C.

Calculation for experiment 1 - 1M HCL

Q = mc Ä T

m = 50g

c = 4.18 Jg-1°C-1

Ä T = 31-36

= -5°C

Q = 50 x 4.18 x -5

= -1045 J

The enthalpy change for 25cm3 = -1045 j

The enthalpy change for 1000cm3 = -1045 x 1000

25

= - 41800 J

= - 41.8 kJ

Uncertainties

Burette =± 0.05 %

Thermometer =± 0.5 %

Pipette = ± 0.1 %

Calculation of Uncertainties...