To determine which alcohol makes the best fuel for burning.

Fair test:

A number of precautions will need to be taken when doing the experiment to make sure everything is fair.

* The container will always have to be kept the same, so the depth of the water stays the same.

* The volume of water must be kept constant (503) and sensible amount of water must be used, as if to little is used the water could evaporate, and there will also be to big an increase in temperature.

* The material of the container used is also important. If a metal container is used the water is likely to be heated quickly as metals conduct heat.

* The time should be kept the same as if an alcohol is kept burning for a longer period of time more fuel will be burnt

* 3 results should be taken for each fuel to make sure that

Prediction:

I predict that the more bonds there are holding the carbon, oxygen and hydrogen atoms, the more energy will be needed to break the bonds. Ach type of alcohol requires a certain amount of energy before all the bonds are broken.

The more bonds there are in a chain length the more Hydrocarbons there will be. Hydrocarbons are the source of potential energy, which is converted into kinetic energy. Therefore if the alcohol contains more hydrocarbons more energy will be released into the atmosphere when the energy is converted.

Scientific theory:

Energy is released when new bonds are formed. If the bond is to be broken a sufficient amount of energy is required

Amount of energy required to break certain bonds:

Chemical bond

Energy required to break bond (J)

C-H

413

O-H

464

C-O

358

C-C

346

C=O

745

O=O

497

The breaking of bonds is an endothermic reaction meaning heat is taken in. The breaking of making of bonds is an exothermic reaction meaning heat is given out.

The bonds that are formed from an exothermic reaction can be one of two types. The first is an ionic bond, which involves electrons transferring from one atom to another. The other type is covalent bonding, which is where electrons are shared to complete their outer orbit.

The formulas for the alcohols used are:

Alcohol

Formula

Ethanol

C2H5OH

Propanol

C3H7OH

Brutanol

C4H9OH

Pentanol

C5H11OH

Hexanol

C6H13OH

Heptanol

C7H15OH

Octanol

C8H15OH

When the chain length increases the amount of energy needed to break the bonds increases.

The following equation can be used to calculate the amount of energy released from a fuel.

E=mc?T

E=Energy

m=mass

c=specific heat capacity

T=change in temperature (final temperature-initial)

Results:

Name of fuel

Mass of fuel +container before burning

Mass of fuel +container after burning

Temperature of H2O before burning (C?)

Temperature of H2O after burning (C?)

79.69

74.75

25

36

Ethanol

95.29

94.86

22

31

94.86

94.13

22

32

200.39

98.82

24

41

Propanol

98.41

89.72

24

37

98.82

97.51

22

46

204.08

203.02

21

34

Butanol

203.07

202.88

21

43

219.99

217.63

26

45

216.08

214.92

25

55

Pentanol

214.78

213.42

25

50

213.42

211.83

26

51

220.39

28.36

25

82

Hexanol

219.02

217.68

24

47

217.68

216.42

26

55

75.80

216.36

25

42

Heptanol

207.80

206.66

25

47

206.66

205.33

26

51

203.27

202.38

25

31

Octanol

202.38

201.61

24

36

201.61

200.78

25

34

Evaluation:

There were a number of factors in this experiment that lead to some of the results being slightly out.

. Heat conducted and convected away through the air

2. Radiation of heat out into the atmosphere

3. Change in temperature of tin

4. At high temperatures heat is lost faster to the air, which makes higher temperatures more inaccurate

5. Evaporation of water

6. Evaporation of alcohol after burning

7. Flame size changed due to type of alohol. How the experiment is stopped and whether it is on time

8. Different size of burner wick

9.

0.

1.

2.