Will precipitation occur when you add 0.05 mL of 0.10 M KBr to a saturated solution of AgCl?

1 Answer
Oct 22, 2016

Answer:

Yes, precipitation will occur.

Explanation:

We must first calculate the concentration of #"Ag"^+# in the saturated solution of #"AgCl"#.

#"AgCl(s)" ⇌ "Ag"^+"(aq)" + "Cl"^"-""(aq)"; K_text(sp) = 1.8 × 10^"-10"#
#color(white)(mmmmmmm)x color(white)(mmmmm)x#

#K_text(sp) = ["Ag"^+]["Cl"^"-"] = x^2 = 1.8 × 10^"-10"#

#x = 1.34 × 10^"-5"#

#["Ag"^+] = 1.34 × 10^"-5"color(white)(l) "mol/L"#

Add 0.05 mL of 0.10 mol/L #"KBr"# to 1.0 mL of the saturated #"AgCl"# solution. Will a precipitate form?

#["Br"^"-"] = "0.10 mol/L" × (0.05 color(red)(cancel(color(black)("mL"))))/(1.05 color(red)(cancel(color(black)("mL")))) = 4.8 × 10^"-3" color(white)(l)"mol/L"#

#"AgBr(s)" ⇌ "Ag"^+"(aq)" color(white)(m)+color(white)(m)"Br"^"-""(aq)"; color(white)(m)K_text(sp) = 5.0 × 10^"-13"#
#color(white)(mmmmmll) 1.34 × 10^"-5" color(white)(mml)4.8 × 10^"-3"#

#Q_text(sp) = ["Ag"^+]["Br"^"-"] = 1.34 × 10^"-5" × 4.8 × 10^"-3" = 6.4 × 10^"-8"#

#Q_"sp" > K_"sp"#

∴ A precipitate will form.