The density of liquid carbon disulfide, CS2, is 1293 kg m–3. Calculate the change in the molar Gibbs energy of carbon disulfide when it is compressed by a change in pressure from 1.00 bar to 4.00 bar.

The change in the molar Gibbs energy of carbon disulfide is 1102.31 kJ/mol.

Explanation:

∆G = ∆H - T∆S

Using the steam table,

At 1 bar,

T1 = 99.6°C

H1 = 417 kJ/kg

S1 = 1.303 kJ/kg.K

At 4 bar,

T2 = 143.6°C

H2 = 605 kJ/kg

S2 = 1.776 kJ/kg.K

T = T2 - T1 = 143.6 - 99.6 = 44°C = 44+273 = 317 K

∆H = H2 - H1 = 605 - 417 = 188 kJ/kg

∆S = S2 - S1 = 1.776 - 1.303 = 0.473 kJ/kg.K

∆G = 188 - 317(0.473) = 188 - 149.941 = 38.059 kJ/kg

Density of CS2 = 1293 kg/m^3

Molar volume = 0.0224 m^3/mol

Change in molar Gibbs energy of CS2 = ∆G × density × molar volume = 38.059 kJ/kg × 1293 kg/m^3 × 0.0224 m^3/mol = 1102.31 kJ/mol