Do large molecules transfer more energy when they burn?

(more heat is given out). More energy will be needed to break the bonds apart as we go down the list as there will be more bonds to break.

APPARATUS:

1) Thermometer

2) Stopwatch

3) Metal beaker

4) Copper tin

5) 100g water

PLAN:

1) Set up apparatus as shown in the diagram

2) In results table, write the start temperature of the water and the start mass of the

substance.

3) Light the substance at the wick.

4) When the temperature of the water in the metal beaker increases by 20? blow out the wick to stop the experiment.

5) Write the end temperature down in your result table.

6) Measure the substance and write down the mass at the end of the reaction in the result table.

7) Repeat this 3 time.

8) Repeat step 1-7 for each substance.

APPARATUS:

1) Thermometer

2) Metal beaker

3) Copper tin

4) Substance

5) 100g water

RESULTS:

methanol

repeats

mass at start

mass at end

change in mass

temp at start

temp at end

increase

34.4

36

.6

21

41

20

2

29.8

28.3

-1.5

9

39

20

3

28.3

26.8

-1.5

9

39

20

average

-1.5

20

Butanol

repeats

mass at start

mass at end

change in mass

temp at start

temp at end

increase

05.8

04.3

-1.5

22

44

22

2

04.4

02.6

-1.7

22

49

27

3

02.6

01.4

-1.2

9

39

20

average

-1.5

23.5

octanol

repeats

mass at start

mass at end

change in mass

temp at start

temp at end

increase

04

02.9

-1.1

25

50

25

2

02.9

01.8

-1.1

24

44

20

3

01.9

00.9

-1

22

44

22

average

-1.1

22.5

propanol

repeats

mass at start

mass at end

change in mass

temp at start

temp at end

increase

12.7

11.3

-1.4

9

50

20

2

11.3

09.8

-1.5

9

44

20

3

09.8

08

-1.8

9

44

20

average

-1.6

20

ethanol

repeats

mass at start

mass at end

change in mass

temp at start

temp at end

increase

13.4

12.3

-1.1

21

41

20

2

12.3

10.9

-1.4

21

41

20

3

10.9

09.6

-1.3

20

40

20

average

-1.2

20

AVERAGES

Energy released joules = temp increase x mass of water x specific heat capacity of water

Energy released = 20 x 100 x 4.2=8400j/g

Methanol

8400j = 5600j/g

.5

Butanol

8400

.5 =5600j/g

Octanol

8400

.1 = 7636.36j/g

Propanol

8400

.6 =5250j/g

Ethanol

8400

.2 =7000

.3

CONCLUSION:

My results show that as the number of particles are increased, the energy transferred was also be increased. This is because as the numbers of particles are increased, the energy transferred was also be increased. We used methanol, ethanol, propanol, butonol and octanol.

The word and symbol equations for these reactions are:

Methanol:

Methanol + oxygen carbon dioxide + water

C2H5OH + 3O2 2CO2 +4H20

Ethanol:

Ethanol + oxygen carbon dioxide + water

C2H5OH + 3O2 2CO2 + 3H20

Propanol:

Propanol + oxygen carbon dioxide + water

2C3H7OH + 9O2 6CO2 + 8H2O

Butanol:

Butanol + oxygen carbon dioxide + water

C4H9OH + 6O2 4CO2 + 5H2O

Octanol:

Octanol + oxygen carbon dioxide + water

C8H17OH + 12O2 8CO2 + 9H2O

All of these reactions are exothermic reaction. At the start of each reaction, less energy is taken in to break the bonds than is given out at the end of the reaction when new bonds are being made

(more heat is given out). More energy will be needed to break the bonds apart as we go down the list as there will be more bonds to break.

EVALUATION:

I think that the test was not a fair test. There are a number of reasons for this:

) The copper can is metal. Metal is a good conductor of heat; therefore some of the heat released in this reaction would have been collected in the copper can.

2) There was window close by to where we did the experiment. A draft could have come through and made a few results inaccurate.

3) Not all-key variables were controlled i.e. "the same increase in temperature."

To improve this experiment we could have closed the window so the draft could not interfere with our results. If this was controlled we would have got more accurate result. I think the apparatus we used was good enough for the experiment.