Question

Complete combustion of 4.30 g of a hydrocarbon produced 14.0 g of CO2 and 4.30 g of H20. What is the empirical formula for the hydrocarbon? Insert subscripts as necessary. empirical formula: CH

Answer 1

let in compound number of moles of C and H be x and y respectively

Number of moles of CO2 = mass of CO2 / molar mass CO2
= 14.0/44
= 0.3182

Number of moles of H2O = mass of H2O / molar mass H2O
= 4.3/18
= 0.2389

Since 1 mol of CO2 has 1 mol of C
Number of moles of C in CO2= 0.3182
so, x = 0.3182

Since 1 mol of H2O has 2 mol of H
Number of moles of H = 2*0.2389 = 0.4778

Divide by smallest:
C: 0.3182/0.3182 = 1
H: 0.4778/0.3182 = 1.5

Multiply by 2 to get simplest whole number ratio:
C: 1*2 = 2
H: 1.5*2 = 3
So empirical formula is:C2H3

Answer: C2H3