Calculate the amount of heat ( in kJ) required to convert 344.0 g of liquid water at 22.5 oC into steam at 145.0 °C. ( Heat of vaporization of water at its boiling point = 40.7 kJ/mol., specific heats of water and steam are 4.184 J/g °C and 2.01 J/g °C, respectively. )
Ti = 22.5 oC
Tf = 145.0 oC
here
Cl = 4.184 J/g.oC
Heat required to convert liquid from 22.5 oC to 100.0 oC
Q1 = m*Cl*(Tf-Ti)
= 344 g * 4.184 J/g.oC *(100-22.5) oC
= 111545.44 J
Lv = 40.7KJ/mol =
40700J/mol
Lets convert mass to mol
Molar mass of H2O = 18.016 g/mol
number of mol
n= mass/molar mass
= 344.0/18.016
= 19.0941 mol
Heat required to convert liquid to gas at 100.0 oC
Q2 = n*Lv
= 19.0941 mol *40700 J/mol
= 777131.4387 J
Cg = 2.01 J/g.oC
Heat required to convert vapour from 100.0 oC to 145.0 oC
Q3 = m*Cg*(Tf-Ti)
= 344 g * 2.01 J/g.oC *(145-100) oC
= 31114.8 J
Total heat required = Q1 + Q2 + Q3
= 111545.44 J + 777131.4387 J + 31114.8 J
= 919792 J
= 920. KJ
Answer: 920. KJ
Get Answers For Free
Most questions answered within 1 hours.