What is the molarity of a NaCl solution if the addition of excess AgNO₃ to a 40 mL sample of the solution yields 0.123 g of AgCl?

Question

Quizplus · Accepted Answer

Firstly, write the balanced equation for the reaction: NaCl + AgNO3 → AgCl + NaNO3
Next, calculate the number of moles of AgCl formed: 
Mass of AgCl = 0.123 g 
Molar mass of AgCl = 143.32 g/mol 
Number of moles of AgCl = 0.123 g ÷ 143.32 g/mol = 8.575 x 10^-4 mol
Since AgNO3 is in excess, all the NaCl in the solution would be used up. Thus, the number of moles of NaCl in the sample is also 8.575 x 10^-4 mol. 
Finally, calculate the molarity of the NaCl solution: 
Molarity = number of moles ÷ volume in liters 
Volume = 40 mL ÷ 1000 = 0.04 L 
Molarity = 8.575 x 10^-4 mol ÷ 0.04 L = 0.021 molar.

What Is the Molarity of a NaCl Solution If the Addition