Question

In an experiment, 15.0g of ice at -30 degrees Celsius is converted into steam with a temperature of 115 degrees Celsius. How much energy (in kJ) is required for this process?

Answer 1

Ti = -30.0
Tf = 115.0
here
Cs = 2.09 J/goC

Heat required to convert solid from -30.0 oC to 0.0 oC
Q1 = m*Cs*(Tf-Ti)
= 15 g * 2.09 J/goC *(0--30) oC
= 940.5 J

Lf = 333.0 J/g

Heat required to convert solid to liquid at 0.0 oC
Q2 = m*Lf
= 15.0g *333.0 J/g
= 4995 J

Cl = 4.184 J/goC

Heat required to convert liquid from 0.0 oC to 100.0 oC
Q3 = m*Cl*(Tf-Ti)
= 15 g * 4.184 J/goC *(100-0) oC
= 6276 J

Lv = 2260.0 J/g

Heat required to convert liquid to gas at 100.0 oC
Q4 = m*Lv
= 15.0g *2260.0 J/g
= 33900 J

Cg = 2.03 J/goC

Heat required to convert vapour from 100.0 oC to 115.0 oC
Q5 = m*Cg*(Tf-Ti)
= 15 g * 2.03 J/goC *(115-100) oC
= 456.75 J

Total heat required = Q1 + Q2 + Q3 + Q4 + Q5
= 940.5 J + 4995 J + 6276 J + 33900 J + 456.75 J
= 46568 J
= 46.6 KJ

Answer: 46.6 KJ