Question

Ag+ (aq) + Cl- (aq) → AgCl (s) Silver chloride is virtually insoluble in water so that the reaction appears to go to completion. How many grams of solid NaCl must be added to 25.0 mL of 0.251 M AgNO3 solution to completely precipitate the silver?

Answer 1

Answer:

0.367 g

Explanation:

Precipitation of silver and Cl requires 1:1 mol ratio of silver and Cl each, so the amount of mol NaCl (provides 1 mol of Cl⁻) and AgNO₃ (privides 1 mol of Ag⁺) must be equal for complete precipitation.

mol of Ag⁺ we have is

$mol_{Ag^+}=[AgNO_3]*V_{solution}\\ =0.251*0.025=0.006275\ mol$

Thus we need 0.00625 mol of NaCl as well

The molar mass of NaCl is 58.44 g/mol

Therefore the total grams of NaCl needed is

$m_{NaCl}=58.44*0.006275\\ =0.367\ g$