Precipitate if saturate solution?

Question

How many grams of NaNO3 will precipitate if a saturated solution of NaNO3 in 200g H2O at 50C is cooled to 20C?

Answer 1

Look up the solubilities (from a solubility curve) at 50 and 20C. Double them, and then subtract.

Answer 2

often talking, a saturated answer is one that can't dissolve any extra solute into the solvent. Now evaluate this challenge: you're making a saturated answer of glucose at 25°C. you be certain that it truly is saturated because there's a touch undissolved, extra glucose on the bottom of the sphere. Now you very intently withdraw a quantity of the saturated answer, and move it to a unique field. If the temperature is maintained at 25°C, all is nicely yet imagine that the temperature ingreases to 20-eight°C. Do you nevertheless have a saturated answer? No. because the solubility of the glucose is more effective at 28°C than at 25°C Conversely, might want to the temperature drop to 22°C, the glucose answer will change into oversaturated and the further glucose will precipitate out of answer. So the secure plan of action is to make a answer of sufficiently intense concentration that there is continually a touch undissolved solute on the bottom of the sphere. If any small chamges in temperature do take position, up or down, the answer will continually be saturated, and also you're particular of this by seeing the undissolved extra solute on the bottom of the sphere. As some distance Ksp is in contact, that's continually quoted at a particular temperature, many times 25°C. Ksp refers for sure to very sparingly soluble elements, alongside with AgCl. yet what I somewhat have reported above in connection with glucose applies both nicely to AgCl. once you need to make certain the Ksp experimentally, you've a saturated answer, with the very small quantity of AgCl in answer, and some undissolved AgCl contained in the sphere. you be certain that the saturtaed answer is carefully mixed, and the precipitate of AgCl has all settled out, and then you intently eliminate the saturated answer above the precipitate for diagnosis. If there isn't any precipitate seen on the bottom of the sphere, you are able to't be particular that the answer's saturated.