I got an answer 5.7958kJ is incorrect, please help to fix. Calculate the number

Question

I got an answer 5.7958kJ is incorrect, please help to fix.

Calculate the number of kilojoules of energy required to convert 25.0 grams of solid ethanol initially at a temperature of -114.0°C to gas at 125.0°C. kJ Specific Heat Capacity Liquid m.w. m.p. b. .p vap Solid Gas substance Ethanol Water DMSO t-Butanol formula g/mol H20 C2H6SO C4H1o0 46.069-114.0 78.0 18.015 0.0 78.129 19.0 74.123 25.2 100.0 189.0 82.4 5.02 6.01 14.4 6.78 38.6 40.67 48.6 39.1 0.970 2.09 1.80 1.97 2.30 4.184 1.96 2.9 1.94 1.84 1.20 1.73

Explanation / Answer

Ti = -114.0 oC

Tf = 125.0 oC

here

Hfus = 5.02KJ/mol =

5020J/mol

Lets convert mass to mol

Molar mass of C2H5OH = 46.069 g/mol

number of mol

n= mass/molar mass

= 25.0/46.069

= 0.5427 mol

Heat required to convert solid to liquid at -114.0 oC

Q1 = n* Hfus

= 0.5427 mol *5020 J/mol

= 2724.2337 J

Cl = 2.3 J/g.oC

Heat required to convert liquid from -114.0 oC to 78.0 oC

Q2 = m*Cl*(Tf-Ti)

= 25 g * 2.3 J/g.oC *(78--114) oC

= 11040 J

Hvap = 38.6KJ/mol =

38600J/mol

Heat required to convert liquid to gas at 78.0 oC

Q3 = n* Hvap

= 0.5427 mol *38600 J/mol

= 20947.2953 J

Cg = 1.94 J/g.oC

Heat required to convert vapour from 78.0 oC to 125.0 oC

Q4 = m*Cg*(Tf-Ti)

= 25 g * 1.94 J/g.oC *(125-78) oC

= 2279.5 J

Total heat required = Q1 + Q2 + Q3 + Q4

= 2724.2337 J + 11040 J + 20947.2953 J + 2279.5 J

= 36991 J

= 37.0 KJ

Answer: 37.0 KJ

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