The link between the numbers of carbon atom in a fuel with the amount of energy it releases.

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CHEMISTRY COURSEWORK

THE LINK BETWEEN CARBON ATOMS IN A FUEL AND THE ENERGY IT RELEASES.

PLANNING

INTRODUCTION

Alcohols generally belong to compounds whose molecules are based on chains of carbon atoms. They usually contain one oxygen atom, which is joined to a carbon atom by a singular bond. This makes them different to other compounds. The oxygen atom is joined to the hydrogen atom as well as the carbon atom, which makes the oxygen a part of a hydroxyl group. These atoms are generally a part of a hydrocarbon chain. These alcohols can take away water from the body, in which a hydrocarbon chain has replaced a hydrogen atom. Alcohols have a general structure of CnH2n+1OH

The aim of this investigation is to see the link between the numbers of carbon atom in a fuel with the amount of energy it releases. There would be a change in the amount of energy given off, that is getting greater, the more carbon atoms in the fuel, the more there are more bonds to be broken and formed, thus producing more energy. 'In a chemical reaction, bonds in the reactant molecule are broken and new ones are formed. Atoms are rearranged. Energy has to be put in to break bonds, and energy is given out when bonds are formed.' When the total energy put in is greater than the energy put out, the substance cools down (it is endothermic). This is expressed as ? +ve (delta positive). If the total energy put in is less than the energy created, then the substance warms up (it is exothermic). This is expressed as ? -ve (delta negative).

I will investigate eight different alcohols using an alcohol or spirit burner, to measure the energy change by measuring the change in water temperature. To hold the water I need some sort of container. This container must be a heat resistant, so it can use little of the energy from the reaction as possible. Probably the most conductive container available for use in the classroom is a calorimeter. As well as not wasting energy in the heating of the container, I could also try to stop heat from escaping around the edges of the container. I will try to prevent the wind from blowing the flames to a different direction so all the windows must be shut.

HYPOTHESIS

More energy is released as more bonds are formed, below is the list of approximate energy required to breaking all bonds in an alcohol.

TYPE OF BOND ENERGY REQUIRED TO BREAK THE BOND (j)

C-H 410

C-O 360

O-H 510

C-C 350

Below is the calculation of all the alcohols I have decided to use. They are as follows:

* Methanol has three C-H bonds, one C-O bond and one O-H bond therefore the calculation would be: (3?410) + 360 + 510 = 2100

* Ethanol has five C-H bonds, one C-O bond, one C-C bond and one O-H bond therefore the calculation would be: (5?410) + 360 + 350 + 510 = 3270

* Propan-1-ol has seven C-H bonds, 2 C-C bond, one C-O bond and one O-H bond therefore the calculation would be: (7?410) + 360 + (2? 350) + 510 = 4440

* Butan-1-ol has nine C-H bonds, 3 C-C bond, one C-O bond and one O-H bond therefore the calculation would be: (9?410) + 360 + (3?350) + 510 = 5610

* Pentan-1-ol has eleven C-H bonds, 4 C-C bonds, 1 C-O bond and one O-H bond therefore the calculation would be: (11?410) + (4?350)+ 360 + 510 = 6780

* Hexan-1-ol has 13 C-H bonds, 5 C-C bonds, one C-O bond and one O-H bond therefore the calculation would be: (13?410) + 360 + (5?350) + 510 = 7950

* Heptan-1-ol has 15 C-H bonds, 6 C-C bonds, one C-O bond and one O-H bond therefore the calculation would be: (15?410) + 360 +(6?350) + 510 = 9120

* Octan-1-ol has 17 C-H bonds, 7 C-C bonds, one C-O bond and one O-H bond therefore the calculation would be: (17?410) + 360 + (7?350) + 510 = 10170

From the above, I would find out who much energy how much energy is released.

* Methanol + Oxygen ==> Carbon dioxide + Water

* 2CH3OH + 3O2> 2CO2 + 4H2O

* 2(2100)+3(496)>2(2?360)+4(2?510) =

5688-5520=168

* Ethanol + Oxygen==> Carbon dioxide + Water

* 2C2H5OH + 6O2 > 4CO2 + 6H2O
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* 2 (3270)+6(496)>4(720)+6(1020)

9516-9000=516

* Propan-1-ol + Oxygen ==> Carbon dioxide + Water

* 2C3H7OH + 9O2 > 6CO2 + 8H2O

* 2(4440)+9(496)>6(720)+6(1020)

3344-12480=864

* Butan-1-ol + Oxygen ==> Carbon dioxide + Water

* 2C4H9OH + 12O2 > 8CO2 + 10H2O

* 2(5610) + 12(496) > 8(720) + 10(1020)=

* Pentan-1-ol + Oxygen ==> Carbon dioxide + Water

* 2C5H11OH + 15O2 > 10CO2 + 12H2O

* 2(6780) + 15(496) > 10(720) + 12(1020)

* Hexan-1-ol + Oxygen ==> Carbon dioxide + Water

* ...

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