Effect of Temperature on Solubility

[Sassenav22]

Homework Statement

Please help me chemistry is my worst subject

I did an experiment to test the effect of temperature on solubility. A hot water was add to salicylic acid and stirred. More salicylic acid was add until some of it remained undissolved. Samples of the mixture of water and the salicylic acid was taken at 50, 45, 40, 35, 30 and 25 degrees. Each sample was titrated with 0.02M NaOH

1)I was wondering if someone can explain the equilibrium of a solid and a saturated solution and equilibrium constant.

2) Could somebody explain these equations to me:

lnB = -delta H/RT + delta S/R

delta G = delta H - T(delta S)


2) Using a lnB versus 1/T graph how would u find Delta H.

Homework Equations

The Attempt at a Solution

 

[Nino MMP]

1) A solid and a saturated solution in equilibrium means that the solubility of the solid in the solution is equal to the concentration of the dissolved solid. The equilibrium constant, K, is a measure of the equilibrium between the two states and can be calculated using the equation K = (concentration of dissolved solid)/(concentration of solid).2)The first equation, lnB = -delta H/RT + delta S/R, is called the van't Hoff equation. It relates the equilibrium constant B to the enthalpy (delta H), entropy (delta S) and temperature (T) of a reaction. The second equation, delta G = delta H - T(delta S), is an expression of Gibbs free energy. It describes the difference in enthalpy and entropy between the reactants and products of a reaction.3)To find Delta H from a lnB versus 1/T graph, you would first plot your data points on the graph. Then, draw a best-fit straight line through the points. The slope of this line is equal to -Delta H/R, so you can calculate Delta H by multiplying the slope by R.