When 2.701 grams of a hydrocarbon, C_xH_y, were burned in a combustion analysis apparatus, 9.132 grams of CO_2 and 1.870 grams of H_2O were produced. In a separate experiment, the molecular weight of the compound was found to be 78.11 amu. Determine the empirical formula and the molecular formula of the hydrocarbon. Enter the elements in the order presented in the question.