A batch of 40-wt-% NaOH solution in water at atmospheric pressure and 80(F) is heated in an

Question:

A batch of 40-wt-% NaOH solution in water at atmospheric pressure and 80(°F) is heated in an insulated tank by injection of live steam drawn through a valve from a line containing saturated steam at 35(psia). The process is stopped when the NaOH solution reaches a concentration of 38 wt-%. At what temperature does this occur?