[HDG]

"A substance containing 28.84% Nitrogen, 0.0648g Hydrogen, and Oxygen and Carbon, with (total) mass (of the substance) 1.2953, is burned in excess oxygen to produce 2.241 grams of carbon dioxide.
Find the mass of Carbon.
Find the mass of Oxygen.
Find the emperical formula of the compound. "

pls help me with this question...
the answer i got was CH4NO2

[Borek]

Are you sure about the numbers you entered? Please recheck for typos.

Show how you got CH₄NO₂. Doesn't look correct to me, but then answer I am getting doesn't make much sense either.

[HDG]

So Nitrogen mass is 28.84% of 1.2953=0.3736g
Hydrogen=0.0648

mass of carbon:  CO₂ moles is 2.241/44=0.05093

since there are three atoms 0.05093/3=0.016978

1 atom of carbon means  0.016978x1=0.016978

Mass of carbon: 0.016978x12=0.2037g

mass of Oxygen:  1.2953-(0.2037+0.3736+0.0648)=0.6532g

EF:
C:  0.2037g/12 = 0.016978
H:  0.0648/1    = 0.0648
N:  0.3736/14  = 0.02668
O:  0.6532/16  = 0.041

when doing the ratios:
C: 1
H: 4
N: 1
O: 2

Therefore EF of compound is: CH₄NO₂

[HDG]

what is the answer you are getting? is it C₄HN₂O ?

[DevaDevil]

mass of carbon:  CO₂ moles is 2.241/44=0.05093

since there are three atoms 0.05093/3=0.016978

1 mole of CO₂ contains how many moles of C?

[HDG]

i made a ratio of the total moles of CO2 to the number of atoms... so i could get the portion of moles of carbon in CO2
and then i used that to convert to mass

[DevaDevil]

I am sorry to tell you, but read up again on the mole - definition.

1 mole of CO₂ consists of 1 mole of C and 2 moles of O

[HDG]

i was finding the number of moles in 2.241 grams of CO₂

[DevaDevil]

and you did that correctly. then you divided that by 3 to find the number of moles of carbon, which was incorrect.