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A/S Chemistry

Hi what is the best method to work the answer out for this question:

Write an equation for the complete combustion of the alkane which requires 11 moles of oxgen per mole of alkane for complete combystion.

Reply 1

FaerieLand

put
alkane + 11o2 -> water + CO2 then balance it?

Reply 2

Barny

17

Which alkane?

Reply 3

vinny2256

6

supreme

Hi what is the best method to work the answer out for this question:

Write an equation for the complete combustion of the alkane which requires 11 moles of oxgen per mole of alkane for complete combystion.

I dont think any alkane or alkene will react with 11 moles of o2 in complete combustion. It doesnt work out.

Reply 4

etomac

C7h16 + 11o2 --> 7co2 + 8h2o

Reply 5

Sza

Alkane

C7 H16 + 11o2 ----> 7Co2 + 8H2o

work out how many atoms of oxygen there are, then case of trial and eorror really. Eg you know for C5H12 your gonna need at least 10 atoms of for co2 and the atoms of oxygen in h2o is just generally half of the hydrogen number. So you know it s a bit more 'cause you want 22. Soz, that was a really bad explanation but essentially its trial and error

Reply 6

PermaBored

No it doesn't.

Look again

7CO2 will require 14 moles of O2 on its own.

Reply 7

Sza

PermaBored

No it doesn't.

Look again

7CO2 will require 14 moles of O2 on its own.

Geezer, 14 moles of o2 has 28 atoms of oxygen. 7 co2 has 14 atoms (not moles) of oxygen and 8 h20 has 8 atoms (not moles) of oxygen.

hence 22 atoms are required of oxygen (o), which is found in 11 moles of oxygen (o2) (which is 22 atoms of O).

Reply 8

PermaBored

CH4 requires 4 moles of O2 to fully combust

C (2mol) H4 (2mol)

C2H6 7 moles
C3H8 10 moles
C4H10 13 moles.

No alkane requires 11 exactly.

This sounds like a typical Edexcel question.

Reply 9

PermaBored

Whoops.

Silly O2's going round in pairs :tongue:

Reply 10

vinny2256

6

Sza

Alkane

C7 H16 + 11o2 ----> 7Co2 + 8H2o

work out how many atoms of oxygen there are, then case of trial and eorror really. Eg you know for C5H12 your gonna need at least 10 atoms of for co2 and the atoms of oxygen in h2o is just generally half of the hydrogen number. So you know it s a bit more 'cause you want 22. Soz, that was a really bad explanation but essentially its trial and error

This is the CORRECT ANSWER.

Reply 11

supreme

OP

4

Thanks I used the right method then :smile:

A/S Chemistry

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