Question 1
Calculate the minimum concentration of Cr
3+ that must be added to 0.095 M NaF in order to initiate a precipitate of chromium(III) fluoride. (For CrF
3 , K
sp = 6.6 × 10
–11.)
◦ 0.023 M
◦ 0.032 M
◦ 7.7 × 10
–8 M
◦ 2.9 × 10
–9 M
◦ 6.9 × 10
–10 M
Question 2
Calculate the minimum concentration of Mg
2+ that must be added to 0.10 M NaF in order to initiate a precipitate of magnesium fluoride. (For MgF
2 , K
sp = 6.9 × 10
–9.)
◦ 1.4 × 10
7 M
◦ 6.9 × 10
–9 M
◦ 6.9 × 10
–8 M
◦ 1.7 × 10
–7 M
◦ 6.9 × 10
–7 M