The specific heat of solid water (ice) and liquid water are 2.03 J/gºC and 4.18 J/gºC respectively. Heating a 49.3 g sample of
ice from -25.0°C to water at 44.7 °C requires 28.23 kJ of heat.
Calculate the heat of fusion of water in J/g. Assume the melting
point of water is 0 °C.

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's all four options.