chemistry alevel

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Thread starter 3 months ago
#1
under suitable conditions , a mixture of carbon monoxide and hydrogen reacts to form water and a mixture of hydrocarbons
nCO + (2n +1 )H2 -> nH2O + hydrocarbons
what is the general formula for the hydrocarbons produced ?
CnH2n-1
CnH2n
CnH2n+1
CnH2n+2
can some one please explain why is the answer D ?
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3 months ago
#2
(Original post by staerryynighht)
under suitable conditions , a mixture of carbon monoxide and hydrogen reacts to form water and a mixture of hydrocarbons
nCO + (2n +1 )H2 -> nH2O + hydrocarbons
what is the general formula for the hydrocarbons produced ?
CnH2n-1
CnH2n
CnH2n+1
CnH2n+2
can some one please explain why is the answer D ?
plug in a random number for n and see what is missing on the other side to balance out the hydrogens.
Try plugging in 3 for example and see what needs to multiply/add/minus to the hydrogen in the hydrocarbon to balance out the equation.
we focus on the hydrogen as the oxygens and carbons are already balanced out.
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Thread starter 3 months ago
#3
(Original post by sara.m12)
plug in a random number for n and see what is missing on the other side to balance out the hydrogens.
Try plugging in 3 for example and see what needs to multiply/add/minus to the hydrogen in the hydrocarbon to balance out the equation.
we focus on the hydrogen as the oxygens and carbons are already balanced out.
i plugged 3 so it gives 7 which is 14H On the left AND Then on the right 6 H soo i need 8 more to balance but how does this make it clear that the ans is D ?
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3 months ago
#4
(Original post by staerryynighht)
i plugged 3 so it gives 7 which is 14H On the left AND Then on the right 6 H soo i need 8 more to balance but how does this make it clear that the ans is D ?
Because the same rule will work for every number that u plug in. Try 4
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3 months ago
#5
(Original post by staerryynighht)
under suitable conditions , a mixture of carbon monoxide and hydrogen reacts to form water and a mixture of hydrocarbons
nCO + (2n +1 )H2 -> nH2O + hydrocarbons
what is the general formula for the hydrocarbons produced ?
CnH2n-1
CnH2n
CnH2n+1
CnH2n+2
can some one please explain why is the answer D ?
D is the standard formula for hydrocarbons because the middle section of the hydrocarbon will always be H-C-H (which is why its 2n), and each end will need an extra H to complete the 4 bonds per carbon (which is why you +2, one extra H for each end).
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Thread starter 3 months ago
#6
(Original post by sara.m12)
Because the same rule will work for every number that u plug in. Try 4
oh my god tysmmm got it ! may u explain this one too i got it wrong in my exam how do u read it
0
3 months ago
#7
(Original post by staerryynighht)
oh my god tysmmm got it ! may u explain this one too i got it wrong in my exam how do u read it
The answer is C. You ALWAYS have to identify the longest chai in this case 8 carbons make the longest chain.
A tip is to write down “C” on the skeletal points to avoid confusion.
So the longest chain is 8C therefore the ending will be octane.
There r no ethyl groups, only 3 methyl groups. One on the 3rd 4th and 6th carbon.
Tri- because three methyl groups.

In order you write this as
3,4,6-trimethyloctane
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Thread starter 3 months ago
#8
(Original post by sara.m12)
The answer is C. You ALWAYS have to identify the longest chai in this case 8 carbons make the longest chain.
A tip is to write down “C” on the skeletal points to avoid confusion.
So the longest chain is 8C therefore the ending will be octane.
There r no ethyl groups, only 3 methyl groups. One on the 3rd 4th and 6th carbon.
Tri- because three methyl groups.

In order you write this as
3,4,6-trimethyloctane
can u pls draw it without the skeletal structure
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3 months ago
#9
(Original post by staerryynighht)
can u pls draw it without the skeletal structure
Drawn out
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