In the reaction AgNO3 + NaCl → AgCl(s) + NaNO3, mixing 0.040 mol AgNO3 with 0.010 mol NaCl, which reagent is limiting and how many moles of AgCl form?

• A. NaCl is limiting; 0.040 mol AgCl forms
• B. NaCl is limiting; 0.010 mol AgCl forms
• C. AgNO3 is limiting; 0.040 mol AgCl forms
• D. AgNO3 is limiting; 0.010 mol AgCl forms

Answer: (B)

In this reaction, AgNO3 and NaCl combine in a 1:1 ratio to make AgCl and NaNO3. The smaller amount among the reactants determines how much product can form. You have 0.040 mol of AgNO3 and 0.010 mol of NaCl, so NaCl runs out first and is the limiting reagent. Since each mole of NaCl yields one mole of AgCl, only 0.010 mol of AgCl can form. The remaining 0.030 mol of AgNO3 stays unused, but no more AgCl can precipitate.