Question

La Ce Pr Nd Pm Sm Eu Gd Tb Но Er Tm Yb Lu Cane SM4 Ac Th Np Pu Am Cm Bk Cf Fm Md No LEM J004 berum A 6.807 g sample of an unknown compound, composed only of carbon, hydrogen, and nitrogen, produced 13.3 g of CO, and 9.52 g of H2O in a combustion analysis. What is the mass percent composition of nitrogen of the unknown compound? Round to one decimal place. Provide your answer below:

Answer 1

Number of moles of CO2 = mass of CO2 / molar mass CO2

= 13.3/44

= 0.3023

Number of moles of H2O = mass of H2O / molar mass H2O

= 9.52/18

= 0.5289

Since 1 mol of CO2 has 1 mol of C

Number of moles of C in CO2= 0.3023

so, x = 0.3023

Since 1 mol of H2O has 2 mol of H

Number of moles of H = 2*0.5289 = 1.058

Molar mass of N = 14.01 g/mol

mass N = total mass - mass of C and H

= 6.807 - 0.3023*12 - 1.058*1

= 2.122

Now use:

Mass % of N = mss of N * 100 / total mass of sample

= 2.122 * 100 / 6.807

= 31.17 %

Answer: 31.2 %