Heat of displacement (Find the change of temperature)

In an experiment, excess magnesium powder is added to 50 cm³ of 0.25 mol dm^-3 

iron(ll) sulphate solution. The thermochemical equation is shown below,

       Mg(s)   +   Fe²⁺ (aq)  à  Mg²⁺ (aq)  +   Fe (s)                  ΔH =  -80.6 kJ mol ^{- 1}  

What is the change in temperature?

[ Specific heat capacity of solution : 4.2 J g^{-1 0}C^-1 . Density of solution : 1 g cm^-3 ]

(ans: 4.8 ^oC)