Alcohol Combustion Experiment

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Adam Franks 10BW

GCSE
CHEMISTRY
COURSEWORK

Skill Area:“P”.  Planning.

Background information

The breaking of bonds is endothermic, and the making of bonds is exothermic. The difference between the two decides whether a reaction is exothermic or endothermic. We can calculate the theoretical change in energy, by using given values, of the energy required to break certain bonds.

Prediction

I predict that if the Mr value of the alcohol / and the number of carbon atoms is increased that the heat of combustion will increase.  I predict that the heat of combustion will increase in a regular manner aswell.

Equations

1C2H5OH + 3O2                         2CO2 + 3H2O

1C3H7OH + 4.5O2                         3CO2 + 4H2O

1C4H9OH + 6O2                         4CO2 + 5H2O

1C5H11OH + 7.5O2                         5CO2 + 6H2O

1C6H13OH + 3O2                         6CO2 + 7H2O

PREDICTING HEATS OF COMBUSTION, BY CALCULATING THEM USING BOND ENERGY VALUES.

  1. Ethanol

H        H

H                C        C        O        H     + 3O=O                      2O=C=O +         O

H        H

H        H

Heat of Combustion  = +4728-6004

▲H     = -1276 kJ mol –1

  1. Propanol

H        H   H

1 H    C    C    C         O    H + 4.5O=O                           3=O=C=O + 4O

H    H    H

H              H

Heat of Combustion  = +6648-8542

▲H     = -1894 kJ mol –1

  1. Butanol

H        H   H    H

1 H    C    C    C         C      O    H + 6O=O                        4=O=C=O + 5O

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H    H    H         H

H            H

Heat of Combustion  = +8568-11080

▲H     = -2512 kJ mol –1

  1. Pentanol

H H H H H

1 H    C C C C C     O    H + 6O=O                        5=O=C=O + 6O

H H H H H

H             ...

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