The molar integral heat of solution s H is defined as the change in enthalpy that

The molar integral heat of solution Δ_sH is defined as the change in enthalpy that results when 1 mole of solute (component 1) is isothermally mixed with N₂ moles of solvent (component 2) and is given by

Δ_sH is easily measured in an isothermal calorimeter by monitoring the heat evolved or absorbed on successive additions of solvent to a given amount of solute. The table below gives the integral heat-ofsolution data for 1 mol of sulfuric acid in water at 25°C (the negative sign indicates that heat is evolved in the dilution process).

a. Calculate the heat evolved when 100 g of pure sulfuric acid is added isothermally to 100 g of water. 

b. Calculate the heat evolved when the solution prepared in part (a) is diluted with an additional 100 g of water.

c. Calculate the heat evolved when 100 g of a 60 wt % solution of sulfuric acid is mixed with 75 g of a 25 wt % sulfuric acid solution.

d. Relate (H1 − H1) and (H2 − H2) to only N1, N2, ΔHs, and the derivatives of ΔHs with respect to the ratio N2/N1. 

e. Compute the numerical values of (H₁ − H₁) and (H₂ − H₂) in a 50 wt % sulfuric acid solution.

Transcribed Image Text:

AsH = (1 + N₂)Hmix - H₁- N₂H₂ = H₁ + N₂H₂ - H₁-N₂H₂