CEE 680

Fall 2011

Homework #5

1. Determine the pH and alkalinity for the following solutions. Assume the systems are closed to the atmosphere.

a. 5x10-4F NaOH

b. 5x10-5F Na2CO3

c. 5x10-5F KHCO3

d. 1x10-3F HCl

2. What partial pressure of carbon dioxide are the solutions from question #1 in equilibrium with?

3. Repeat question #1, but assume the systems are open to the atmosphere.

4. A groundwater was found to have the following composition:

ANC = 3x10-2 equ/L, pH = 7.5

What is the partial pressure of CO₂ that is in equilibrium with this water?

5. A surface water and a groundwater are to be used as a raw water supply for the town of Springfield, FL. They will be mixed as follows:

	Surface Water	Groundwater
Flow Rate	3.5 MGD	0.8 MGD
Alkalinity	10 mg/L as CaCO3	250 mg/L as CaCO3
pH	6.9	8.3

What will the pH of the combined waters be?

Assigned: 19 Oct 11

Due: 26 Oct 11