This reaction formula follows: 2AgNO3 + Na2SO4⇒ Ag2SO4 + 2NaNO3. So the molar ratio between the reactants is AgNO3:Na2SO4 = 2:1. To calculate the moles of NaSO4: 0.274M*0.155 L = 0.04247 mole. According to the above ratio (2:1), the moles of AgNO3 required for a complete reaction is 0.04247 * 2 = 0.08494 mole. Since the concentration of AgNO3 is 0.305M, the volume of AgNO3 is 0.08494mole/0.305M= 0.2785 L = 278.5 mL.
