A salt A is soluble in a solvent S. A conductivity meter used to measure the solute concentration in A-S solutions is calibrated by dissolving a known quantity of A in S, adding more S to bring the solution volume to a fixe value, and noting the conductivity meter reading. The data given below are taken at 30 degrees C.
Solute dissolved (g) Solution volume (mL) Meter reading R
0 100 0
20 100 30
30 100 45
The following experiment is performed. 160g of A is dissolved in S at 30 degrees C. S is added until a final solution volume of 500 mL is obtained. The solution is cooled slowly to 0 degrees C while being stirred and is maintained at this temperature long enough for crystallization to be complete. The concentration of A in the supernatant liquid is then measured with the conductivity meter, yielding R=17.5. The solution is next reheated in small temperature increments. The last crystal is observed to dissolve at 10.2 degrees C. A SG of 1.10 may be assumed for all A-S solutions.
Please help me a) derive an expression for C (g A/mL solution) in terms of R.
b) calculate the solubilities (g A/100 gS) at 10.2 degrees C and 0 degrees C and the mass of solid crystals in the breaker at 0 degrees C. and if you have the time, I'd really appreciate help with:
c) if half the solvent in the flask were to evaporate at 0 degrees c, how much more A would come out of solution?