[thomas49th]

Hi, I know that ethonal is formed by reacting ethene with steam over a strong catalyst (such as phosphuric acid)

C₂H₄ + H2O => C₂H₅O

Have I balanced this right:

CH₄ + 3O₂ => 2CO₂ + 2H₂O

ALSO

Ethonal can be oxidise to form ethanoic acid. Carboxylic acids have the function group COOH, so where does the extra carbon come from when Ethonal is oxidised to make ethanoate:
     H   H     O
     |    |    //
H - C - C - C -O - H
     |    |         
     H   H           

Thankyou

[Dan]

Have I balanced this right:

CH₄ + 3O₂ => 2CO₂ + 2H₂O

No, C is not balanced.

ALSO

Ethonal can be oxidise to form ethanoic acid. Carboxylic acids have the function group COOH, so where does the extra carbon come from when Ethonal is oxidised to make ethanoate:
     H   H     O
     |    |    //
H - C - C - C -O - H
     |    |         
     H   H           

Thankyou

You don't get an extra carbon. The structure you've drawn is propanoic acid. Ethanoic acid is CH₃COOH.

[thomas49th]

1) o i missed out the 2 at the begging
2) Ok, so the C - H is changed to C =O
                                             |
                                             O - H

[Dan]

1) o i missed out the 2 at the begging

2CH₄ + 3O₂ ---> 2CO₂ +2H₂O is still not balanced

2) Ok, so the C - H is changed to C =O
                                             |
                                             O - H

The -CH₂OH group has been transformed into the -COOH group.

[thomas49th]

2CH₄ + 4O₂ ---> 2CO₂ +4H₂O

Okay now I wondering about carboxylic acid formula:

CnH2n+1COOH                     O
                                         //
Howcome methanoic acid is C - O - H

Wouldn't the formula make it CH₃COOH

[Borek]

n=0

[Farid]

Howcome methanoic acid is C - O - HHowcome methanoic acid is C - O - H

When I was wondering how to called Carboxylic Acid i was doing it like that:
For example, Butane has got 4 carbon atoms, so butanoic acid has 4 carbon atoms as well.One in -COOH group and 3 in carbon chain.

And methanoic it mean there is one C atom. So it's HCOOH.

Wouldn't the formula make it CH₃COOH

CH₃COOH  has got 2 carbon atoms so it's ethanoic acid

[Dan]

Butane has got 5 carbon atoms, so butanoic acid has 5 carbon atoms as well.One in -COOH group

4 carbon atoms.

[thomas49th]

Meth = 1
Eth = 2
Prop = 3
But = 4
Pent = 5

so how can n = 0 for methanoic acid?

The formula works for alkanes and alchohols

However the alchohols formula is C_nH_2n+1OH
CH₃OH
C = 1
H = 2(1) + 1
OH

that's methonal.... you dont have to take carbons from the function group there unlike what you said

CH3COOH  has got 2 carbon atoms so it's ethanoic acid

it doesn't make sense....

[Dan]

Eth = 2

CH3COOH  has got 2 carbon atoms so it's ethanoic acid

it doesn't make sense....

You recognise that 2 carbon atoms results in the prefix "eth", so why does it not make sense that ethanoic acid has 2 carbon atoms?

However the alchohols formula is C_nH_2n+1OH
CH₃OH

Ok let's break down the logic to this formula. The formula is an alkyl chain and OH functionality

C_nH_2n+1OH

where n=1, Me; n=2, Et;...

Now, when naming carboxylic acids the C in the carboxylic acid functionality does contribute to the prefix.
An analogous formula for alkyl carboxylic acids with alkyl chain and COOH functionality would be:

C_n-1H_2n-1COOH

Where n=1, Me; n=2, Et;...

eg, if n=1, it's methanoic acid, with the formula C_1-1H_2(1)-1COOH = HCOOH

The formula you posted for carboxylic acids:

C_nH_2n+1COOH

is valid if you recognise that the C of the COOH is contributing to the prefix, ie. that
n=0, Me; n=1, Et;... as Borek said.

As you can see, the lesson here is that thinking in these n=... formulas to determine the name is really overcomplicating something that is remarkably simple. Just count the carbon chain, that way you can't go wrong.

[thomas49th]

Thx