[kep1]

The question is...
A hydrocarbon burns completely, producing 7.2g of H2O and 14.14g of CO2 at standard conditions. What is the hydrocarbon's empirical formula?

1m H2O = 18g H2O
H = 1/9 of 1m H2O
(1/9) * 7.2g = .8g H
.8g H = .8m H

1m CO2 = 44g CO2
C = 3/11 of 1m CO2
14.14g * (3/11) = 3.856g C
3.856g C = .3213m C

.8/.3213 = 2.49
so we have C1H2.49 which = C2H5.

is this correct?

[Borek]

OK

[khemistry101]

looks fine to me

[potatopotato]

Looks Great 

[AWK]

Note, in the case of saturated hydrocarbons (C_nH_2n+2), sometimes you can get also a real formula from this type of calculations. In your case C₄H₁₀ is a real formula of your hydrocarbon.