Question

A 50.0 mL sample of 1.54×10−2 M NaSO4 is added to 50.0 mL of 1.28×10−2 Ca(NO3)2. What percentage of the Ca2+ remains unprecipitated?

Answer 1

NaSO4 does not exist. Are you sure that is what was written in the problem?

Answer 2

sorry Na2SO4

Answer 3

Alright, well do you have any ideas on how to approach this problem?

Answer 4

find n of Na2SO4 and the n of Ca(NO3)2

Answer 5

Alright. What does finding those values do for progressing in the problem?

Answer 6

helps find the ksp

Answer 7

i think

Answer 8

Well, you won't be able to find the Ksp. You would look up the Ksp in a table in this particular case since you are trying to determine how much precipitate would form.

Answer 9

do you need to find the limitting reagent

Answer 10

I apologize, but I must leave. I'll be back in a bit to help you if you are still having troubles.

Answer 11

thanks,
I would calculate moles Ca^+2 and moles SO4^=, from an ICE chart you will know which is the limiting reagent and from there which is the common ion (that will be the one in excess). Then calculate the solubility and from there how much remains. Find percent of that.

Answer 12

but i dont really understand how to do it

Answer 13

There is not a limiting reactant in cases of solubility. In the equation for K_sp... \[K_{sp}=[A][B]\]The K_sp is constant (at 25C), but the ratio of A:B does not necessarily have to be 1:1.

Answer 14

If [A] decreases, [B] would need to decrease, and vice-versa.

What you need to do is set up the situation BEFORE the sodium sulfate solution is added. Then, as you add the sodium sulfate, the calcium sulfate will begin precipitating. Once the products of the concentrations of the calcium cation and the sulfate anion equals the K_sp, you know how much precipitate will form.

Answer 15

thanks