Question

How many kilojoules of energy are needed to convert 83.0 g of ice at -13.7 to water at 24.4°C? (The specific heat of ice at -13.7 is 2.01 J/g°C.)

Answer 1

Ti = -13.7

Tf = 24.4

here

Cs = 2.01 J/goC

Heat required to convert solid from -13.7 oC to 0.0 oC

Q1 = m*Cs*(Tf-Ti)

= 83 g * 2.01 J/goC *(0-(-13.7)) oC

= 2286 J

Lf = 333 J/g

Heat required to convert solid to liquid at 0.0 oC

Q2 = m*Lf

= 83 g *333.0 J/g

= 27639 J

Cl = 4.184 J/goC

Heat required to convert liquid from 0.0 oC to 24.4 oC

Q3 = m*Cl*(Tf-Ti)

= 83 g * 4.184 J/goC *(24.4-0) oC

= 8473 J

Total heat required = Q1 + Q2 + Q3

= 2286 J + 27639 J + 8473 J

= 38398 J

= 38.4 KJ

Answer: 38.4 KJ