Chemical energy.
chemica
Fuels contain a store of energy called
When fuels are burned the
energy. Some fuels, called
were formed from the remains of plants or
energy is changed into
fossil
fuels,
Coal was formed from dead
The plants were buried in
, which stopped them
away.
More mud buried and squashed them. The mud turned into
and the dead plants turned into
that lived in
Oil and gas were formed from plants and
to the sea bed and were
the sea. When they died they
buried. Over
of years they were squashed and heated,
and turned into

oh it is true if thats what you are asking

answer: the enthalpy of the overall chemical reaction is +87.88 kj or +88 kj.

according to hess's law, the overall enthalpy of a reaction is the difference between the sum of enthalpy values of all the products and the sum of enthalpy values of all the reactants.

δh(reaction) = ∑nδh(products) - ∑nδh(reactants)

δh(reaction) = [δh +δh] - [δh]

δh(reaction) = [1(-287.02) + 1(0) ] - [1(-374.9)] kj = +87.88 kj

here, δh (pcl3) = -287.02 kj, δh(cl2) = 0, δh(pcl5) = -374.9 kj

therefore, enthalpy of the overall reaction is +87.88 kj or +88 kj.

it is the most commonly accepted one