Acid/Base Reactions!

Today in chemistry class we learned about pH and P0H, we also had visitors in class watching as we used our phones to text Mr. Doktor our answers for the in class problems.

Our 1st class problem was:


2000mL of 0.02 M NaOH represented our simulated lake and 150mL of 0.30 M HCl represented our simulated acid rain.

First we had to determine the pH of the acid rain and the pOH of the lake.

Determining the pH of the acid rain:

HCL -> H+ + Cl-

0.30 M x 1/1 = 0.30 M
-log(.30 = 0.52 = pH

Determining the pOH of the lake:

NaOH -> Na+ + OH-

0.02M x 1/1 = 0.02M
-log(0.02 = 1.7 = pOH

Determining the pH of the lake after acid rain has fallen on it:

HCl + NaOH -> NaCl + HOH

0.30mol/L x 0.150L = 0.045mol HCl

0.02mol/L x 2.00L = 0.04mol NaOH

0.045 - 0.040 = 0.005 mol

0.0050 x 1/2.15 = 0.002326M

-log(0.002326 = 2.6 = pH

Then we had to do another in class problem:

50.0mL of 0.150M H2SO4 reacts with 100mL of 0.100M Ba(OH)2



a) Determine the L.R.

H2SO4 -> 2H+ + SO4-2

0.150mol/L x 0.050L x 2/1 = 0.015mol of H, 0.015 x 1/2 = 0.0075mol of H2SO4

Ba(OH)2 -> Ba+ + 2OH-

0.100mol/L x 0.100L x 2/1 = 0.02mol of OH, 0.02 x 1/2 = 0.01mol of BaOH

H is L.R.


b) How much Ba(OH)2 is left after the reaction is completed

0.01 - 0.0075 = 0.0025 mol of BaOH is left

0.0025mol x 1/.150 = 0.017M


c) Determine the [Ba(OH)2] and [OH]

[Ba(OH)2] = 0.0025mol x 1/0.150 = 0.017M

[OH] = 0.017M x 2/1 = 0.034M


d) What is the pOH of the solution?

-log(0.034 = 1.48 = pOH


e) What mass of BaSO4 is produced?

0.0075mol x 1/1 x 233.4/1 = 17.5g of BaSO4