Question

Menthol, which is derived from oil of mint, is a C, H, O compound. Its molar mass is 156.3 g/mole. If 95.6 mg of menthol is burned in oxygen, 269 mg of carbon dioxide and 110 mg of water are produced. Find menthol’s empirical and molecular formulas.

Please show all work involved.

Answer 1

no of mol of CO2 = 0.269/44 = 0.00611 mol

No of mol of H2O = 0.11/18 = 0.00611 mol

so that

No of mol C in sample = 0.00611 mol

No of mol of H in sample = 2*0.00611 = 0.01222 mol

mass of O in sample = (0.0956 - (0.00611*12+0.01222)) = 0.01006 grams

No of mol of O in sample = 0.01006 /16 = 0.00062875 mol

simplest ration of c,h,o

C = 0.00611/0.00062875 = 9.7

H = 0.01222/0.00062875 = 19.4

O = 0.00062875/0.00062875 = 1

simplest whole number ratio

C = 10 , H = 20 , O = 1

so that ,

molecular formula = C10H20O