confirmation please

[cindyy]

I'm not sure whether this is right of not, so i was wandering if someone could confirm it for me !

Q: If a compound containing carbon and hydrogen is burned in air or oxygen, carbon dioxide and water are formed.  Methyl salicylate has the common name of oil of wintergreen and is often used in medical rubs.  A 20.00 g sample of Methyl salicylate, which contains carbon hydrogen and oxygen only, was burnt in oxygen.  The mass of water and carbone dioxide was 9.47 g and 46.30 g respectively.  Calculate the empirical formula of Methyl salicylate.

My answer was C₈H₈O₃.  Somehow i just dont think that is correct

[vexx]

n(CO2)=1.05mol
x1 :.n(C)=1.05mol

n(H20)=0.53mol
x2 :.n(H)=1.05mol

m(O)=20g - (mol of other two x their molar mass)
=20-(12.6+1.05)
=6.32g
n(o)=0.39mol

n(c):n(H):n(o)
= 1.05:1.05:0.39
divide by 0.39
2.7:2.7.1
x3 all

:.= C8H8O3

ah all right:P

[cindyy]

siqq  8-)

well i have another question, and i dont know the answer to this question!

Q: Liquid ammonia, NH₃, is widely used by farmers as a fertilizer.  Industrially, ammonia is produced by the haber process.  Hydrogen and nitrogen gases are introduced into a steel container, in the stoichiometric proportions.  A total mass of 340 g gases are introduced into a 20 L steel container at 25 degrees celcius.

(b) The total mass of hydrogen and nitrogen is 240 g.  What is the mass of each gas if mixed in stoichiometric proportions?

[fady_22]

siqq  8-)

well i have another question, and i dont know the answer to this question!

Q: Liquid ammonia, NH₃, is widely used by farmers as a fertilizer.  Industrially, ammonia is produced by the haber process.  Hydrogen and nitrogen gases are introduced into a steel container, in the stoichiometric proportions.  A total mass of 340 g gases are introduced into a 20 L steel container at 25 degrees celcius.

(b) The total mass of hydrogen and nitrogen is 240 g.  What is the mass of each gas if mixed in stoichiometric proportions?

Ok, so the equation is: 3H2+N2-------->2NH3
By using m=n*mr:
n(H2)*2 + n(N2)*28= 240 (as the masses of both add up to equal 240)

But n(H2)=3*N(N2)
Sub n(H2) into the equation:
3n(N2)*2 + n(N2)*28= 240
n(N2)=7.06 mol

m(N2)=n*mr=7.06*28= 198 g
m(H2)= 240-198
        =42.4 g

[cindyy]

thank youuu i get it now