Which chemical is the limiting reagent for the entire series of reactions? why?
0.020mol A + 0.20mol B -> 0.020mol C
0.1mol D + 0.020mol chemical C -> 0.040mol Chemical E
0.1mol F + 0.040mol chemical E -> 0.020mol Chemical G
0.1mol H + 0.12mol chemical G -> 6.66mol Chemical I

To predict if a precipitate will form when 2 solutions are mixed:

• Calculate the concentration of individual ions in the combined solution (remember to divide mol of ion by the TOTAL

solution volume)

• Calculate the ion product, Q (same form as Ksp, but ion concentrations here are not necessarily equilibrium ion

concentrations)

• Compare Q to Ksp

• If Q > Ksp, the solution is supersaturated, ion concentrations are greater than equilibrium concentrations, reaction will

proceed in reverse to reach equilibrium, precipitation will occur.

• If Q < Ksp, the solution is unsaturated, ion concentrations are less than equilibrium concentrations, reaction will proceed

forward to reach equilibrium, more solid will dissolve.

• If Q = Ksp, the solution is saturated, the solution is at equilibrium, ion concentrations are equilibrium concentrations, no

more solid will dissolve or precipitate.

Explanation:

• What minimum concentration of Na2CO3 (aq) is required to cause precipitation of BaCO3 (s) from a solution of 1.0 x 10—5

M BaCl2 (aq)?

BaCO3 (s) ↔ Ba2+ (aq) + CO3

2— (aq); Ksp = 2.6 x 10—9

logic: At the point where Q = Ksp the solution is at equilibrium. Calculate the concentration of CO3

2— that will satisfy this

relationship:

Q = [Ba2+][CO3

2—]; 2.6 x 10—9 = 1.0 x 10—5[CO3

2—]

[CO3

2—] = 2.6 x 10—4 M

This is the concentration of Na2CO3 that will result in a saturated solution (solid and ions in equilibrium). SO . . . any

[Na2CO3] greater than 2.6 x 10—4 M will result in Q > Ksp and precipitation of BaCO3.