[Taylor08]

I haven't had chemistry in 3 years so I am having trouble with answering these practice problems. My textbook does not provide alot of examples on how to work these kinds of problems. Showing the work would help me better understand on how to set the problems up.

1. Calculate [OH-] for 2.170 g of LiOH in 300.0 mL of solution. [OH-] = ? M

2. How many moles of HF (Ka = 6.8 x 10-4) must be present in 0.160 L to form a solution with a pH of 3.30?

3. Calculate the molar concentration of [OH-]ions in a 7.0×10−2 M solution of ethylamine (C2H5NH2) (Kb= 6.4 x 10-4)

4. Calculate [OH-] and pH for a solution of 7.0 x 10-2 M NaCN? I am not sure if I need Kb or Ka for this equation.

5. What is the pH of a solution that is 3.0×10−9 M in NaOH? Would I do the log (3.0 x 10-9) and then subtract that number from 14 in order to get the pH?

6. How many milliliters of concentrated hydrochloric acid solution (36.0% HCl by mass, density = 1.18 g/mL) are required to produce 10.0 L of a solution that has a pH of 1.99?

Your help is greatly appreciated!

[plankk]

This task are concerned on few grasps, like molar concentration, pH, equilibirum, Henderson–Hasselbalch equation.

[X] means a molar concentration. Look here for some information. http://en.wikipedia.org/wiki/Molar_concentration