Question

To lift fingerprints from a crime scene, a solution of silver nitrate is sprayed on a surface to react with the sodium chloride left behind by perspiration. What is the molarity of a silver nitrate solution if 42.8 mL of it reacts with excess sodium chloride to produce 0.148g of precipitate according to the following reaction?

AgNO3(aq)+NaCl(aq) --> AgCl(s)+NaNO3(aq)
A) 2.41 x 10^-2 M
B) 0.0229 M
C) 6.66 x 10^-2 M
D) 3.2 x 10^-3 M
E) 2.29 x 10^2 M

Answer 1

A) 2.41 * 10^-2 M

Step-by-step explanation:

Here we go from grams of percipitate to moles of Silver nitrate because we already know NaCl is excess so we don't care about that.

`0.148gAgCl * (1mol AgCl)/(143.32 g AgCl) * (1 mol AgNO3)/(1 mol AgCl)\\ = 0.00103 mol AgNO3`

Now that we have moles we know molarity is moles/litres so we just plug it in:

Molarity = mol/litres = 0.00103/0.0428 L = 0.0241 M or 2.41 * 10^-2 M