Qualification > Sciences

who have answers to this book???(edexcel)

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The Golden Girl =D:

--- Quote from: Relina on November 30, 2010, 09:49:09 pm ---well I have questions but cando the screen shot so I will give u the page 23 Q3 if u could do it telll me ? if u donot tell mwe to post it here

many Thanks :)

--- End quote ---

I'll working on it :)

I got a)  0.03211  for C , 0.003699 for N , 0.2247 for H , and 0.06033 for O

b) as 9 : 1 : 61 : 16

c) as C9NH61O

d) I didn't know how to solve it  :-X *srry I'm distracted by the TV -.- *

here is the pic ppl :)


 

Deadly_king:
Here's my working.

a) Make use of the formula ---> No of moles = Mass/Mr
Oxygen : 0.66712/16 = 0.041695
Carbon : 0.3853/12 = 0.032108
Hydrogen : 0.05178/1 = 0.05178
Nitrogen : 0.2247/14 = 0.01605
Phosphorus : 0.2981/31 = 0.0096161

b) To get the ratio, we divide everything by the smallest number which in this case is 0.0096161.

Example : Oxygen -----> 0.041695/0.0096161 = 13/3(nearest)
So the ratio is O    : C      : H      : N     : P
                  13/3  : 10/3 : 16/3  : 5/3   : 1

Now we just have to multiply by 3 to get C10O13N5H16P3. This is the empirical formula. ;)

d) The empirical formula gives us an Mr of 494.

494n = 507 which is almost n=1.

Hence the molecular formula is equal to the empirical one. :D

Molecular formula : C10O13N5H16P3

~ Miss Relina ~:

--- Quote from: Amatu Allah on December 01, 2010, 07:34:02 am ---I'll working on it :)

I got a)  0.03211  for C , 0.003699 for N , 0.2247 for H , and 0.06033 for O

b) as 9 : 1 : 61 : 16

c) as C9NH61O

d) I didn't know how to solve it  :-X *srry I'm distracted by the TV -.- *

here is the pic ppl :)


 


--- End quote ---

Thanks that is great  :D
how did u took the screen shot pm me  ;) other wise I wonot be able to post my questions as they are too long to type  :(

~ Miss Relina ~:

--- Quote from: Martin Luther King Jr on December 02, 2010, 05:29:44 am ---Here's my working.

a) Make use of the formula ---> No of moles = Mass/Mr
Oxygen : 0.66712/16 = 0.041695
Carbon : 0.3853/12 = 0.032108
Hydrogen : 0.05178/1 = 0.05178
Nitrogen : 0.2247/14 = 0.01605
Phosphorus : 0.2981/31 = 0.0096161

b) To get the ratio, we divide everything by the smallest number which in this case is 0.0096161.

Example : Oxygen -----> 0.041695/0.0096161 = 13/3(nearest)
So the ratio is O    : C      : H      : N     : P
                  13/3  : 10/3 : 16/3  : 5/3   : 1

Now we just have to multiply by 3 to get C10O13N5H16P3. This is the empirical formula. ;)

d) The empirical formula gives us an Mr of 494.

494n = 507 which is almost n=1.

Hence the molecular formula is equal to the empirical one. :D

Molecular formula : C10O13N5H16P3

--- End quote ---
Thanks amillion Thanks  :) :)
but I really had too many questions there hope that u could help
ur ansers are really great I will try to do it by meslf now  ;)

Deadly_king:

--- Quote from: Relina on December 02, 2010, 03:26:12 pm ---Thanks amillion Thanks  :) :)
but I really had too many questions there hope that u could help
ur ansers are really great I will try to do it by meslf now  ;)

--- End quote ---

No problem. :)

Do post your doubts and i'll try to help you as much as possible. ;)

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