Question

a) A beaker contains 200.0 mL of 0.250 M AgNO3. 200.0 mL of 0.100 M HCl(aq) is added to it. What is the NO3− concentration in the final mixture?b) What is the Ag+(aq) concentration in the final mixture? (Hint: does anything happen when you mix these solutions?)

Answer 1

According to given data:

No. of mmol of AgNO₃ = 200*0.25, i.e. 50

And no. of mmol of HCl = 200*0.1, i.e. 20

a) The reaction that occurs here can be written as

AgNO₃(aq) + HCl(aq) AgCl(s) + HNO₃(aq)​ + AgNO₃(aq)​.

No. of mmol: 50 20 20 20 30

The no. of mmol of NO₃^- in the final mixture = 20 (from HNO₃) + 30 (AgNO₃), i.e. 50

Total volume = 200 + 200, i.e. 400 mL

Therefore, the NO₃⁻ concentration in the final mixture = 50/400, i.e. 0.125 M

b) The reaction between AgNO3 and HCl gives a precipitate (i.e. AgCl), and unreacted AgNO₃ in the aq. solution.

Here, the no. of mmol of Ag+(aq) in the final mixture = 30

Therefore, the Ag+(aq) concentration in the final mixture = 30/400, i.e. 0.075 M