Calculate the standard enthalpy variation of the following reaction consulting the → Table of formation enthalpies : $Ca_3(PO_4)_2(s)$ $+$ $3H_2SO_4(l)$ $\longrightarrow$ $3CaSO_4(s)$ $+$ $2H_3PO_4(l)$
$\Delta H^o$ $ =$ $(2\Delta H_f(CaSO_4(s))$ $+$ $2\Delta H_f(H_3PO_4))$ $-$ $(\Delta H_f(Ca_3(PO_4)_2(s))$ $+$ $2\Delta H_f(H_2SO_4(l)))$ $=$ $-264.83 \;kJ$