posted by Mahir .
1. The bombardier beetle uses an explosive discharge as a defensive measure. The chemical reaction involved is the oxidation of hydroquinone by hydrogen peroxide to produce quinine and water:
C6H4(OH)2 (aq) + H2O2 (aq) C6H4O2 (aq) + 2 H2O (l)
Calculate ΔH for this reaction from the following data:
C6H4(OH)2 aq --> C6H4O2 aq + H2 g ΔH = +177.4 kJ
H2 g + O2 g --> H2O2 aq ΔH = -191.2 kJ
H2 g + ½ O2 g --> H2O g ΔH = -241.8 kJ
H2O g --> H2O (L) ΔH = -43.8 kJ
Add equation 1 to the reverse of equation 2, then add twice equation 3 and twice equation 4. Cancel atoms/molecules common to both sides and check to make sure you have the equation you want. Don't forget to change the sign of any delta H value for which the equation was reversed. Also, don't forget to multiply the delta H value for any equation multiplied.
Is it -194.6KJ ?