Pure water is used to dilute $172lb$ of a sulfuric acid stream that has an initial mass fraction of $H_{2}S{O}_4$ equal to $0\mathrm{.}85$ in order to

produce a diluted acid with an $H_{2}S{O}_4$ mass fraction of $0\mathrm{.}50.$ The temperature of the water is $40F$ and that of the concentrated acid is

$77F.$

An enthalpy$-$composition diagram for the system is shown below.

Enthalpy$-$concentration chart for $H_{2}S{O}_4-H_{2}O.($Redrawn from the data of W$.$ D$.$ Ross, Chem. Eng. Progr., $43$:$314,1952.)$

DETERMINE THE FINAL TEMPERATURE IF THE PROCESS OCCURS ADIABATICALLY.