Question

How much HgS forms when 113 mL of a 0.75 M CaS solution is mixed with 52 mL of a 1.21 M Hg(NO3)2 solution? Show steps neatly please.

Answer 1

CaS reacts with Hg(NO3)2 according to the reaction :

CaS + Hg(NO3)2 = HgS + Ca(NO3)2

So you may see equimolar amounts of both the reactants are required for the complete reaction.

Here no. of moles of CaS available = 0.113 × 0.75 = 0.08475 moles

No. Of moles of Hg(NO3)2 available = 0.052 × 1.21 = 0.06292 moles.

Now since Hg(NO3)2 is the limiting reagent, the number of moles of HgS formed will be 0.06292 moles.

Molar mass of HgS = 232.66 g/mol

So 0.06292 moles = 0.06292 × 232.66 = 14.64 grams