Question

The following information is given for ether at 1 atm: boiling point = 34.60°C Hvap(34.60°C) = 357.5 J/g melting point = -116.3°C Hfus(-116.3°C) = 98.10 J/g specific heat gas = 1.460 J/g⋅°C specific heat liquid = 2.320 J/g⋅°C A 27.70 g sample of liquid ether is initially at -5.40°C. If the sample is heated at constant pressure (P = 1 atm), __ kJ of energy are needed to raise the temperature of the sample to 59.40°C.

Answer 1

Ti = -5.4 oC

Tf = 59.4 oC

here

Cl = 2.32 J/g.oC

Heat required to convert liquid from -5.4 oC to 34.6 oC

Q1 = m*Cl*(Tf-Ti)

= 27.7 g * 2.32 J/g.oC *(34.6--5.4) oC

= 2570.56 J

Lv = 357.5 J/g

Heat required to convert liquid to gas at 34.6 oC

Q2 = m*Lv

= 27.7g *357.5 J/g

= 9902.75 J

Cg = 1.46 J/g.oC

Heat required to convert vapour from 34.6 oC to 59.4 oC

Q3 = m*Cg*(Tf-Ti)

= 27.7 g * 1.46 J/g.oC *(59.4-34.6) oC

= 1002.9616 J

Total heat required = Q1 + Q2 + Q3

= 2570.56 J + 9902.75 J + 1002.9616 J

= 13476 J

= 13.5 KJ

Answer: 13.5 KJ