Which fuel has the most energy?

Authors Avatar

Science GCSE Coursework

Which fuel has the most energy?

Aim:  The aim of this exercise is to find out, which fuel has the most energy.  The fuels that I will be testing are Methanol, Ethanol, Propanol, Butanol and Pentanol.  All of these fuels are alcohols.

Prediction:  I think that Pentanol will be the fuel that will have the most energy.  I have made this prediction because I worked out the energy needed in each bond and then how much energy is needed in the balanced equations I drew up for each fuel.  

Here are the bond energies: 

C-H       413KJ/mol

C-C       347KJ/mol

C-O       335KJ/mol

O-H       464KJ/mol

O-O       498KJ/mol

C-O       805KJ/mol

Here are the balanced equations:

Methanol: CH3O-H + O2 ----- Co2 + H2o

Ethanol:    C2H5O-H + O2 ----- Co2 + H2o

Propanol:  C3H7O-H + O2 ----- Co2 + H2o

Butanol:    C4H9O-H + O2 ----- Co2 + H2o

Pentanol:   C5H11O-H + O2 ----- Co2 + H2o

Once I had the bond energies I could work out how much energy there was in each fuels structure.  

                           H                

Methanol:  H – C – O – H = CH3 O – H    

                           H

C-H: 3  413 = 1239

C-O: 1  335 = 335

O-H: 1  464 = 464

Total = 1239 + 335 + 464

= 2038KJ/mol

       

                        H   H

Ethanol:  H – C – C – O – H = C2H5O-H

 

                        H   H

C-H: 9  413 = 3717

C-C: 3  347 = 1041

C-O: 1  335 = 335

O-H: 1  464 = 464

Total = 2065 + 347 + 335 + 464

= 3211KJ/mol

                          H   H    H

Propanol:  H – C – C – C – O – H = C3H7O-H

 

                          H   H    H

C-H: 7  413 = 2891

C-C: 2  347 = 694

C-O: 1  335 = 335

O-H: 1  464 = 464

Total = 2891 + 694 + 335 + 464

= 4384KJ/mol

                          H   H    H    H

Butanol:  H – C – C – C – C – O – H = C4H9O-H

 

                          H   H    H    H

C-H: 9  413 = 3717

C-C: 3  347 = 1041

C-O: 1  335 = 335

O-H: 1  464 = 464

Total = 3717 + 1041 + 335 + 464

= 5557KJ/mol

                       

                          H   H   H   H   H         

Pentanol:  H – C – C – C – C – C – O – H = C5H11O-H

 

                          H   H    H    H   H

C-H: 11  413 = 4543

C-C: 4  347 = 1388

C-O: 1  335 = 335

O-H: 1  464 = 464

Total = 4543 + 1388 + 335 + 464

= 6730KJ/mol

Once I had these totals I used my balanced equations to find activation energy.

Methanol:

CH3OH (L) + O2 (G)           CO2 (G) + H2O (G)

Join now!

2H3OH + 3O2               2CO2 + 4H2O

2038  +  3  498        2  1610 + 4  928

3532 KJ/mol            6932KJ/mol

= 3400KJ/mol

Ethanol: 

C2H5OH (L) + O2 (G)         CO2 (G) + H2O (G)

C2H5OH + 3O2               2CO2 + 5H2O

3211  +  3  498            2  1610 + 4  928

3532 KJ/mol                6004KJ/mol

= 3400KJ/mol

Propanol: 

C3H7OH (L) + O2 (G) ...

This is a preview of the whole essay