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.