Question

The decomposition of `H_2O_2` produces water and oxygen gas, releasing 197 kJ per one mole of `H_2O_2`. How much energy is released if we start with 798 grams of `H_2O_2`?

Answer 1

`q=4629.5kJ`

Explanation:

The amount of heat (`q`) released from decomposing `798g` of `H_2O_2` could be found by:

`q=DeltaHxxn` where, `DeltaH` is the enthalpy of the reaction and `n` is the number of mole of `H_2O_2`.

Note that `DeltaH=197kJ*mol^(-1)`

To find `n`, we can simply use: `n=m/(MM)` where, `m=798g` is the given mass and `MM=34g*mol^(-1)` is the molar mass of `H_2O_2`.

`n=m/(MM)=(798cancel(g))/(34cancel(g)*mol^(-1))=23.5molH_2O_2`

Thus, `q=DeltaHxxn=197(kJ)/(cancel(mol))xx23.5cancel(mol)=4629.5kJ`