[Nathan001]

a simple test for the presence of sulphate involves the addition of a barium salt to produce a precipitate of barium sulphate:

Ba2+(aq) + SO42-(aq)---->BaSO4(s)

If a solution contains 4 x10-5M barium ions, what is the maximum possible concentration of sulphate ions in the solution? (Ksp[BaSO4] = 1.1 x 10-10)


What is the pH of a 0.007M solution of NaOH?  Input your answer to 1 decimal place.

[nj_bartel]

What does the first part of what you posted have to do with the second?  I think you're reading two different questions. 


pH = -log[H+]

pOH = -log[OH-]

pH + pOH = 14


Is NaOH a base or acid?  Is it strong or weak?  What does that tell you?

[Yggdrasil]

Please read the Forum Rules.  You should that show you've at least attempted to answer the problem before we will help you.

For the first question, start by writing out the expression for K_sp in terms of the concentrations of barium ions and sulfate ions (if you don't know how to do this, reread the section in your book on the solubility product).