An acidic solution containing 0.010 m la3 is treated with naoh until la(oh)3 precipitates. use the solubility product for la(oh)3 to find the concentration of oh when la3 first precipitates. at what ph does this occur?

Respuesta :

Given:

0.010 M la3 is treated with naoh


The solution to know what is the ph:

La (OH) 3 = La3+ + 3OH-

Ksp = [La3+] [OH-^3

2 X 10^-21 = (0.010 M) [OH-] ^ 3

[OH-] = (2 X 10 ^ -21 / 0.010) ^1/3

[OH-] = 2.63 x 10^-7 M 

= 5.85 x 10^-7 M

This occurs at pOH = 6.23 and pH = 7.77