Question

hydrogen peroxide can decompose to water and oxygen by the following reaction

2H2O2 (l) ------ 2H2O(l) + O2(g) enthalpy=-196kj
calculate the value of q when 5.00g of h20(l) decomposes at constant pressure.

Answer 1

To begin calculating, there is one thing you need to remember :$1 mole of H2O2=34.0148 g$
Then we have $5.00g of H2O2=5/34.0148=0.146995$
As you know decomposition of 2moles now has prodused 196kj
So, q is made due $0.146995 moles of H2O2$$=(-196/2)*0.146995=-14.40551Kj$
I'm sure it will help.