Question

determine ΔG° for the solid dissolving in water. Suppose you use the same solid as in Question #3 (that is, the molar mass is 95.8 g/mol) and obtain the following data:

Mass of solid 2.968 g

Volume of solution 5.37 mL

Volume of water 2.86 mL

Temperature of solution 25.4 °C Part 1:

Determine the concentration of the solid. 5.77 M You are correct.

Determine ΔG° if we assume K = [solid] in the saturated solution in KJ/mol:

I know the formula should be Delta G = -R * T* In(K) -R = 8.3145 J/Mol K T = 298.4 K

What is In (K) and how do I get that and the Delta G? Moles of the solid = mass/molar mass = 2.968/95.8=0.30 moles Molarity = moles/volume of solution =( 0.30/5.37 )x1000 = 5.7693 M ΔG° = -2.303RTlogK = -2.303x8.3145x298.4log(5.77) =5713.8x0.76 =4349.2 Joules =4.3492KJ

This answer comes back as correct but ... where does the -2.303 come from in the formula? I have a follow-up problem that takes into account of the water added to the solution. and can't seem to get that correct.