[gssisk]

I'm having a hard time with percipitant reactions in my Chem 102 lab.  We don't learn anything about how to do them in class, and then we have these ridiculous webassign assignments that present totally new information.

The first question asks me to show the precipitant reaction when H2SO4 is added to a solution containing Ba^2+.  I said Ba^2+ + H2SO4 -> Ba(H2SO4)2.  This was incorrect.

The second question is similar, asking for the precipitant reaction when H2CO3 is added to Ca^2+

Finally, I'm asked what the reaction is when LiOH is added to Al^3+.

Any help you can give would be awesome.  I like to do these things on my own, but it's incredibly frustrating when we're given basically zero direction and are expected to figure it out (with three submissions, no less) on our own.  Thanks in advance.

-Steve

[Vidya]

You need a good understanding of ionic reactions and polyatomic ions.
like first reaction is very popular reaction in chemistry to identify Ba2+ ions.You will get white ppt of BaSO4
second again a very common precipitate of CaCO3 which are white in color.
(Lime stone)
third is again white ppt of Al(OH)3

[Borek]

You just need to consult a solubility table to learn which salts/hydroxides are insoluble. Google one.