Balance the reaction.
a AgNO₃ (aq) + b H₂SO₄ (aq) → c Ag₂SO₄ (s) + d HNO₃ (aq)
Count the atoms of each element on either side:
• Ag : a = 2c
• N : a = d
• O : 3a + 4b = 4c + 3d
• H : 2b = d
• S : b = c
Let c = 1. Then a = d = 2 and b = 1 and all the counts are consistent. So the balanced reaction is
2 AgNO₃ (aq) + H₂SO₄ (aq) → Ag₂SO₄ (s) + 2 HNO₃ (aq)
which is to say 1 mol H₂SO₄ is needed for every 2 mol AgNO₃ to produce 1 mol Ag₂SO₄.
We start with 0.200 mol AgNO₃, so we can use up at most 0.100 mol H₂SO₄ (and leave an excess 0.055 mol). These react together to produce 0.100 mol Ag₂SO₄
Ag₂SO₄ has a molar mass of about 311.79 g/mol, so this reaction will produce a mass of
(0.100 mol) (311.79 g/mol) ≈ 31.2 g Ag₂SO₄