It's hard to find out workbook for problem solving. 

I don't recommend Barron's or Kaplan etc. 

Those books are designed for official standardized exam like AP. 

Also, there're some other workbooks for practice in amazon. 

(i found a few for the key word " chemistry workbook ")

However, they weren't a lot helpful from my past experience, so, I'd rather recommend you might solve all the problems in your textbook. 

Also, you can look up the worsheets in google. 

For example, 

"stoichiometry worksheet pdf" 

or "limiting reactant worksheet pdf with answer"

you can find out so many worksheets, then, it will be much more helpful. 

Whatever you want more practice, or whatever you don't fully understand, 

you type that key word with "pdf" or with"answer" tag. 

I hope this tip helps. 

Thank you!