15 of 21 SolutionThe balanced reaction is HgNO32 aq Na2Saq

Solution

The balanced reaction is

Hg(NO3)2 (aq) + Na2S(aq) --------------------> HgS(s) + 2NaNO3(aq)

42.39/324.7 7.41/78.05 0 0 initial moles

=0.1305 = 0.09494

Thus Na2S is the limitng reagent .

0.03561 0 0.09494 2x0.09494 after reaction

Part A

the mass of product Na2S formed = moles of Na2S x molar mass

= 0.09494 mol x 232.66g/mol

= 22.088g

Part B

The amount of excess reagent reamained = moles of Hg(NO3)2 remained x molar mass

= 0.03561 mol x 324.7 g/mol

=11.56 g