Calculate the molar solubility of MX2, if the Ksp=3.3x10^-8

Question

i already asked this but im confused about one of the steps.

Ksp = (x)(2x)^2 = 4x^3 = 3.3X10^-8

x = solubility = 0.00202M.

but i don't understand do i substitute the x in 4x^3 3.3X10^-8 and then divide by 3.3X10^-8. or am i wrong?

roseanne · Answer

i tried solving it on my own but im confused by the steps and when i calculate i don't end up with 0.00202. please help!

DrBob222 · Answer

4x^3 = 3.3E-8 x^3 = (3.3E-8/4) = 8.25E-9 x= cube root(8.25E-9) = 0.00202 M

roseanne · Answer

thanks! it looks like i was calculating the cube and not the cube root!