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# Chemistry Practical HELP!!! urgent Watch

1. Motor vehicle environmental effects are judged on the grams of carbon dioxide emitted per kilometre of travel.
The combustion equations for bioethanol and the alkane ethane and the energy liberated are:

C2H5OH + 3O2 --> 2CO2 + 3H2O, delta H = -1371 kJ mol-1
and
C2H6 + 7/2O2 --> 2CO2 + 3H2O, delta H = -1560 kJ mol-1

Bearing in mind that the car is driven by the energy liberated, state which fuel would be more environmentally friendly per mol on the basis of these results, giving your reason.

There is however, another factor to be considered. Discuss this and state whether or not your initial conclusion should be altered.
2. (Original post by SwatiL)
Motor vehicle environmental effects are judged on the grams of carbon dioxide emitted per kilometre of travel.
The combustion equations for bioethanol and the alkane ethane and the energy liberated are:

C2H5OH + 3O2 --> 2CO2 + 3H2O, delta H = -1371 kJ mol-1
and
C2H6 + 7/2O2 --> 2CO2 + 3H2O, delta H = -1560 kJ mol-1

Bearing in mind that the car is driven by the energy liberated, state which fuel would be more environmentally friendly per mol on the basis of these results, giving your reason.

There is however, another factor to be considered. Discuss this and state whether or not your initial conclusion should be altered.
You can see that both fuels produce 2 mol of carbon dioxide per mole of fuel burned.

Also that ethane produces more energy by combustion.

So which fuel produces more carbon dioxide per unit of energy?
3. (Original post by charco)
You can see that both fuels produce 2 mol of carbon dioxide per mole of fuel burned.

Also that ethane produces more energy by combustion.

So which fuel produces more carbon dioxide per unit of energy?
I know that ethane produces more energy, but it also requires more oxygen. do i say that for the second part of the question? if not, how do i word it?
4. (Original post by SwatiL)
I know that ethane produces more energy, but it also requires more oxygen. do i say that for the second part of the question? if not, how do i word it?
Oxygen is irrelevant. Pollution is formation of carbon dioxide (greenhouse gas)

You are looking for the fuel that produces more carbon dioxide per unit of energy - that will be the most polluting (from this data)
5. ok then thanks

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