Question

Ethanol is added to gasoline because the oxygen it contains improves gasoline's burning efficiency. Its combustion reaction is given below. CH3CH2OH(l) + 3O2(g) → 2CO2(g) + 3H2O(g) ∆H = - 1236 kJ a) Is this an exothermic or endothermic reaction? _______________ b) If 15.3 grams of pure ethanol is completely converted to products, calculate how much heat is absorbed or released, in: (1) kJ and in (2) kcal c) If 42.7 g of water vapor is produced, how much heat, in kJ, is absorbed or released?

Answer 1

Answer:

A) The reaction is exothermic reaction

B) 46 gm CH3CH2OH  = 1236KJ

15.3 gm ch3ch2OH = 1236/46 x 15.3

= 411.10 KJ..........released

therefore  1 KJ = 0.239 K cal

so, 411.10 x 0.239 kcal

= 98.2529 .................. released

c) 54 gm of H2O produced = 1236KJ

so, 42.7 gm H2O produced = 1236/54 x 42.7KJ

= 977.35 KJ released.

Explanation: