We know that: Q=mL,Q=msΔθ
Given: m1=64 g,θ1=−10∘C,s1=0.5 cal/g∘C,sw=1 cal/g∘C,θ2=100∘C,θ=0∘C,Lv=540 cal/g,Lf=80 cal/g
Let m2 be mass of steam required.
Heat lost by steam to reach 0∘C will be absorbed by ice during −10∘C to water at 0∘C,
m2Lv+m2sw(100−0)=m1×s1[0−(−10)]+m1×Lf
m2×540+m2×1×100=64×0.5×10+64×80
640m2=64×85
m2=8.5 g
Final answer: 8.5 g