Solubility problems?

Question

I have been given a graph of the amount of solubility of two substances. I don't know if it is possible without the graph, but I need help with these questions...

Substance A
Temp./Solubility (g/100gH2O)
0/20
20/34
40/46
60 /58
80 / 72
100 /86

Substance B
0 /10
20 /18
40 /37
60 / 61
80 /100

1) What mass of substance A would you need to add to 325g of water to saturate the solution at 25 C?

2) 27g of substance A is added to 60g of water. At what temperature will the solution be saturated?

3) A saturated solution in 68g of water is cooled from 70 C to 55 C. Waht mass of the solute will crystalize out?

5) You have a saturated solution in 140g of water of substance A at 20 C. What mass of water must you have to contain a saturated solution of substance B at that temperature, given the same amount of solute?

Thanks :)

Answer 1

impossible to give formulas. Help you w/number 1, from there you will have it.

Look at the graph, at the horizontal axis (Temperature) search 25 C, then draw from there a straight perfectly vertical line, where it crosses the curve of solubility, that's the saturation point, from that pont draw a straight horizontal line to find out in the "y" vertical axis the actual solubility of compound A, maybe the units will be in grams of substance per 100 grams of water, (if not, well you must make the proper adjustments to the calculations)
now take the solubility, and multiply it by 325 and divide it by 100 (Rule of three).

A few tips for the rest of the problem:

2) Procedure is in reverse order to 1)
3) Substract the solubilities of substance at these two temperatures, that's the amount of substance pulled out of solution when cooling, per every 100g of water. Then use the "rule of three"
5) Should be no problem, calculate the mass of substance A using the rule of three, then, using the proper graph determine the solubility of substance B at the temp given, finally use again the rule of three to determine the amount of water.

I Know there are several people here that answers with calculations and all the stuff. That's not me, I am not the one to solve someone else's homework. It would't be ethical.
I give guidance and advice, but not going to chew your food for you, even though, that does not make me very popular. Hope you (And everybody) understand.

Advice: If you come to truly understand the "rule of three" believe me, you will have a masterkey for one third of all problems in the universe.

Answer 2

merely permit the gadgets do the artwork for you! you recognize that seventy 5.5g NH4Br will dissolve in 100g of water at 20 C, and you recognize how lots water you have, so merely multiply the solubility via the mass of water to get the mass of NH4Br which will dissolve. For b, multiply the mass of NH4Br via the inverse of the solubility to get grams of water. For c, discover the mass of NH4Br that could desire to be dissolved in 35g of water at 20C and subtract that from the quantity it quite is truthfully contained in the answer (29g) to detect the quantity that precipitates out. merely pay interest on your gadgets and multiply or divide to cancel stuff out till you get what you desire! as far as a powerful internet site, your textbook writer probable has a internet site that is going over occasion issues. Your e book could have even comprise a CD that works out some issues.