[jebus197]

Strontium sulfate has a lower solubility in water at 25 °C than calcium sulfate. On the basis of this information, suggest what you would observe when dilute sulfuric acid is added to a solution of strontium nitrate with a concentration of 5 g per 100 g of water at 25 °C. Write down a balanced chemical equation that is consistent with your observation.

I'm a bit (well totally really) stuck here.

If I take a stab at it my first instinct would be to write down the chemical formulas for the constituent components. So:

H₂SO₄(l) + Sr(No₃)(aq) + H₂O(l)

but that's where I kind of come undone. How can you predict simply from the information provided what will occur in this case?

The same is true of this question:

The addition of a sodium iodide (NaI) solution to a solution of lead nitrate results in the formation of a yellow precipitate of lead iodide. Write down an ionic equation, in which the spectator ions have been removed, for this reaction. You should include the correct state symbols in your equation.

Again the furthest I am able to get with this is simply to write out the chemical constituents.

NaI(l) + Pb(NO₃)₂(l)    PbI₂(s)

If I were to take a stab at answering it, I would proably do this:

Na(l) + (NO₃)₂(l) :rarrow  PbI²(s)

I've done this because I and the Pb are present on both the left and right of the equation. But I'm not sure if this makes any sense, because my understanding of spectator ions are ions that don't play any part in the final equation, they are there at the start of the equation and are there at the end, so they are not considered significant.

I feel like I've been thrown in at the deep end here and am a little out of my depth. It might be a lot to ask, but rather than just straightforward answers (although having the actual answers would be great too!), it would be helpful if someone could work through these questions with me to help me to understand them. I really would like to learn as much about chemistry as I can and I just don't think I know enough about it yet to answer these questions very well. This isn't for a vital test, or anything like that, but (as I am a mature student) then it's important I try to learn something about chemistry.

Also I'm a little confused about state symbols, specifically between a liquid (l) and the symbol (aq), which I guess must mean an aqueous solution (as in a solution suspended in water). Is this correct?

[Borek]

What do you know about calcium sulfate solubility?

For the second question - before precipitation starts solution contains two salts. Write both in dissociated forms, listing separately all ions. Which of these ions will be left in the solution after the precipitation ends?

[opti384]

For the first question, try to connect the solubility with precipitation.

For the second question, let's first try to write the whole equation.

Your attempt was

NaI(l) + Pb(NO3)2(l)    PbI2(s)

but on the product side where did the Na+ ions and NO3 ions go?

Also, the state of NaI and Pb(NO3)2 will be (aq) as they are aqueous solutions.