Empirical formula q?

Question

hi everyone...heres a q im confused on...any help would be appreciated.

vanilla is made up of carbon, hydrogen and oxgen. 15g of vanilla is burned in excess O2 yielding 34.71 g CO2 and 7.104 g H2O. What's the empirical formula of vanilla?

Answer 1

find grams, using molar mass ratios:

34.71 g CO2 @ 12.01 g C / 44.01 g CO2 = 9.47 grams of Carbon

7.104 g H2O @ 2.02 g H / 18.02 g H2O =0.80 grams Hydrogen

15 g total - 9.47 g Carbon - 0.80 g Hydrogen = 4.73 grams of Oxygen

find moles, using molar masses:

9.47 grams of Carbon / 12.01 g/mol = 0.79 moles C

0.80grams Hydrogen / 1.01 g/mol = 0.79moles H

4.73 grams of Oxygen / 16.0g / mol = 0.30 moles O

ratio the moles:

0.79moles C / 0.30 = 2.6 mol C

0.79 moles H / 0.30 = 2.6 mol H

0.30 moles O / 0.30 = 1 mol O

triple to get whole numbers [(2 & 2/3) times3 =8]:

C8 H8 O3

that's your answer: C8 H8 O3