Hydrogen bonding in the trichloromethane-ethyl ethanoate system

> Note the boiling point.

> Continue adding 2 cm3 portions of trichloromethane in this way, recording the boiling point of each mixture, until a total of 10 cm3 has been added.

> Then allow the apparatus to cool down for some time.

> Repeat the experiment, starting with 10 cm3 of trichloromethane and making 2 cm3 additions of ethyl ethanoate, until a total of 10 cm3 has been added.

> Put the results in a chart of boiling point against percentage composition of the mixture by volume.

Fig. 1

Data recorded:

Boiling points of ethyl ethanoate and trichloromethane

Boiling point (°C)

Ethyl ethanoate

70

Trichloromethane

54

Trichloromethane been added to Ethyl ethanoate

Ethyl ethanoate + 2 cm3 of trichloromethane

Boiling point:

First time Second time Third time

71°C 71°C 71°C

Average: 71°C

Ethyl ethanoate + 4 cm3 of trichloromethane

Boiling point:

First time Second time Third time

71°C 72°C 72°C

Average: 71.7°C

Ethyl ethanoate + 6 cm3 of trichloromethane

Boiling point:

First time Second time Third time

72°C 72°C 73°C

Average: 72.3°C

Ethyl ethanoate + 8 cm3 of trichloromethane

Boiling point:

First time Second time Third time

71°C 75°C 74°C

Average: 73.3°C

Ethyl ethanoate + 10 cm3 of trichloromethane

Boiling point:

First time Second time Third time

74°C 75°C 74°C

Average: 74.3°C

Ethyl ethanoate been added to trichloromethane

Trichloromethane + 2 cm3 ethyl ethanoate

Boiling point:

First time Second time third time

61°C 61°C 61°C

Average: 61°C

Trichloromethane + 4 cm3 ethyl ethanoate

Boiling point:

First time Second time third time

65°C 65°C 65°C

Average: 65°C

Trichloromethane + 6 cm3 ethyl ethanoate

Boiling point:

First time Second time third time

67°C 66°C 67°C

Average: 66.7°C

Trichloromethane + 8 cm3 ethyl ethanoate

Boiling point:

First time Second time third time

68°C 68°C 68°C

Average: 68°C

Trichloromethane + 10 cm3 ethyl ethanoate

Boiling point:

First time Second time third time

69°C 68°C 69°C

Average: 68.7°C

Graph of boiling point against percentage composition of the mixture

Conclusion

The more of ethyl ethanoate or trichloromethane that is added the higher the boiling point is but the wider the range of boiling points that the mixture has. This is because there are more hydrogen bonds in the mixture; these bonds attach the molecules together. To break the hydrogen bonds more energy is need. This extra energy, heat energy in this case is that is need to break the bonds is represented as an increase in the temperature need for the solution to change from the liquid state to the gas state. The wide range in the mixture boiling point is because there are more impurities in the solution and the more is added the bigger the range would be.

There were some problems during the experiment for example; some of the mixture escaped throw the opening in the top of the reflux tube because the water could not cool the vapour fast enough. This put an error to the boiling point because by the end the solution was less than when we started. This make easier for the solution to evaporate. It was hard to tell when the real boiling point was.

These errors could be correct by using a better cooling agent and by having a close reflux tube.