Chemistry: Post your doubts here!

[Lucy Black]

7a i) General formula : CnH(2n+1) OH
Now for verifying it that this formula is correct or not let's take example ---> Ethanol which is two carbon alcohol so now put it into formula --> C2H([2*2]+1)OH ===> C2H5OH which means it is correct

ii) To find it's molecular formula we have to calculate emplerical formula mass --> CH3OH --> 12+3+16+1 => 32
Now, mass of 1 mole/emperical formula mass ====> 116/32 ---> 3.625 which is equal to 4
now multiply this number with emperical formula --> 4(CH3OH) ==> C4H7OH

Can you check this second one answer I am not sure fully

its not correct...

 

[♣♠ Magnanimous ♣♠]

its not correct...

Wat is the answer than?

 

[Lucy Black]

Wat is the answer than?

C7H15OH

its w12 32

 

[♣♠ Magnanimous ♣♠]

C7H15OH

its w12 32

let me check it

 

[Lucy Black]

thnxxxx a lot

 

[♣♠ Magnanimous ♣♠]

C7H15OH

its w12 32

There is no paper of w12 32

 

[Lucy Black]

There is no paper of w12 32

Here you have it..

 

[♣♠ Magnanimous ♣♠]

Here you have it..

Don't know the perfect method

 

[Lucy Black]

fine....

 

[♣♠ Magnanimous ♣♠]

hey...can somebody help me out with dis...
its urgent...

Lola_sweet
any guess on "ii"

 

[Lola_sweet]

Lola_sweet
any guess on "ii"

im sorry Lucy Black i just started AS so im clueless
maybe ZaqZainab can help

 

[Lucy Black]

im sorry Lucy Black i just started AS so im clueless
maybe ZaqZainab can help

thnx for helping me out...
but i got the ans...

 

[♣♠ Magnanimous ♣♠]

How?

thnx for helping me out...
but i got the ans...

 

[ZaqZainab]

im sorry Lucy Black i just started AS so im clueless
maybe ZaqZainab can help

Sorry for being late even though you( Lucy Black )got it
I will show you my way maybe it will be easier

ii) General formula of ALCOHOLS CnH(2n+1) OH, as magnanimous stated.
We know the ratio of masses C:H:OH will be 12n:1(2n+1):1*(16+1) from the general formula and they should equate to 116.
The 12,1 and (16+1) are the relative atomic masses
12n+2n+1+17=116
14n=98
n=98/14
n=7

Now just replace the n with 7 in the formula
C7H15OH

 

[♣♠ Magnanimous ♣♠]

Sorry for being late even though you( Lucy Black )got it
I will show you my way maybe it will be easier

ii) General formula of ALCOHOLS CnH(2n+1) OH, as magnanimous stated.
We know the ratio of masses C:H:OH will be 12n:1(2n+1):1*(16+1) from the general formula and they should equate to 116.
The 12,1 and (16+1) are the relative atomic masses
12n+2n+1+17=116
14n=98
n=98/14
n=7

Now just replace the n with 7 in the formula
C7H15OH

Nic method
Thanks

 

[Lucy Black]

How?

Magnanimous...used d same method...

 

[ZaqZainab]

Magnanimous...used d same method...

did he? if he did he would have ended up with he same answer as mine.

 

[♣♠ Magnanimous ♣♠]

Magnanimous...used d same method...

did he? if he did he would have ended up with he same answer as mine.

Actually the thing is ki my maths is poor a looooooot!

 

[Lucy Black]

did he? if he did he would have ended up with he same answer as mine.

i meant to say i used d same method...

 

[ayaman Azmi]

Can anyone post a link for the Cambridge As and A Level Chemistry textbook or at least point me to a thread that does? Thanks in advance