Dilution Questions

[JFK90787]

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OK this has bothered me since I started studying

EG: "What is the molar concentration of Ca+2 in a solution that is prepared by mixing 15mL of .02M CaCl2 with 10mL of .04M CaSo4?"(Answer is .028M for anyone who cares)

OK Calcium isn't one of the ions which is 100% soluble in water, but I know by now that when I do dilution problems like this to just assume 100% dissociation for its salts. But why? I thought only group 1 and a few other things were 100% soluble in water?

Is it because it's an electrolyte? I know all ionic compounds are strong electrolytes, but just because something is a strong electrolyte doesn't mean its molar concentration will reflect 100% dissociation (I.E PbSo4 is a strong electrolyte but its molar concentration of its ions after dissociation should be very low), so why do we assume 100% dissociation for dilution problems?

 

[loveoforganic]

If you get a problem like this and you're not given ksp values, I think you'd just have to assume 100% dissociation.

 

[JFK90787]

If you get a problem like this and you're not given ksp values, I think you'd just have to assume 100% dissociation.

That's the feeling I get too, even though it's wrong *plays Brittney Spears music* but it feels so riiiiiight