Hi Justine,
"4Ca5(PO4)3F(s) + 18SiO2(s) + 30C(s) --> 3P4(g) + 30CO(g) + 18CaSio3(s) + 2CaF2(s).
The question asks if 12.5 g of each of the solids produced in this reaction were combined with 1.7L of water and stirred until no further dissolution occured, which relationship would be true of the resulting solution?
The answer is that the concentration of Ca2+ would be greater than the concentration of SiO32-.
For this answer, I'm wondering if it is as easy as seeing that there is more calcium in our products than SiO3? Or is there some math involved? I think what through me off was the stoichiometric coefficients and how to account for them when we were dissolving in a solvent."
Yeah, I would have just looked at the coefficients of the reaction for this question - because you have a 1:1 ratio of Ca to SiO32- in the second product, and you also dissolve some CaF2 in addition, I would expect there to be more Ca2+ than SiO32-. I wouldn't have done any math for this.
One of the bigger challenges of the chem sections is trying to find the fastest ways to do the math - if you approach the problem the right way you should minimize what math you have to do to about 5 lines max. To do a full Ksp calculation here would be complicated because of common ion effect etc, so I wouldn't approach it this way, especially as they seem to explicitly state that everything dissolves fully.
I hope this helps!
Katt