Consider the equilibrium AgCl(s) Ag + (aq) + Cl (aq) K c = 1.8x10 10 If 500 mL o
ID: 513593 • Letter: C
Question
Consider the equilibrium
AgCl(s) Ag+(aq) + Cl(aq) Kc = 1.8x1010
If 500 mL of 2x104 M NaCl and 500 mL of 2x105 M AgNO3 are mixed. How many moles of AgCl will precipitate? (Hint: don’t forget what happens to the concentrations when you mix the solutions.)
* a) 8x106 moles ( this is the correct answer but i do not understand how it ws calculated)
b) 2.0x105 moles
c) 8x107 moles
d) 2.0x104 moles
e) 1.2x108 moles
Explanation / Answer
[ Ag+ ] = 2 ×10^-5/2 = 1× 10^-5M
[ Cl- ] = 2× 10^ - 4/2 = 1 × 10^ -4M
Ksp = 1.8×10^-10
Ksp = [ Ag+] [ Cl- ]
1.8 × 10^-10 = [ Ag+] × [ 1× 10^-4]
[ Ag+ ] = 1.8 × 10^-6
mole of Ag+ dissolved = 1.8 × 10^-6
Mole of Ag+ undissolved = (1×10^-5)-(1.8 × 10^-6)=8.2 × 10^-6
No of mol of AgCl formed = 8 × 10^-6