what is

lead (II) acetate + hydrogen sulphide -->

Pb(C2H3O2)2 + H2S -->

how do i figure it out?

1 answer

You remember two things.
a. Reactions go to completion for one of three reasons.
1. a ppt is formed. For this you need to know the solubility rules. In this case PbS is formed which is a ppt.
2. a gas is formed. For this you need to know what is a gas and what isn't. In the periodic table there is some unity in that H2, N2, O2, F2, Cl2, (and perhaps Br2) are gases + common gases such as C2H2, CH4, CO, CO2, H2S etc.
3. a weak electrolyte is formed. Weak electrolytes are weak acids, weak bases, H2O, and one or two others. In this case HC2H3O2 (acetic acid) is formed and that is a weak acid.

So there are two reasons for this reaction.
Pb(C2H3O2)2 + H2S ==> PbS(s) + 2HC2H3O2