Postlaboratory Calculations And Discussionpart B

For each sample calculate the pHs and the other parameters requested. Do not consider here the value of alkalinity as equivalent to that of bicarbonates.

WATER SAMPLE

Ionic strength

logjca2+

log^HCOj-

Temp., K

pKa2

PKsp

Treated sample I

Treated sample 2

Treated sample 3

Treated sample 4

Treated sample 5

Treated sample 6

WATER SAMPLE

pCa2+

pHCOi

pHs

pH

Langelier Index

Ryznar Index

Treated sample 1

Treated sample 2

Treated sample 3

Treated sample 4

Treated sample 5

Treated sample 6

WATER SAMPLE

Reaction quotient, Q

AG"

AG

pH

Treated sample 1

Treated sample 2

Treated sample 3

Treated sample 4

Treated sample 5

Treated sample 6

Based on the above results, state your conclusions with respect to the characteristics of the solutions analyzed and classify each one. Justify each answer, on the basis of the values calculated and those measured.

WATER SAMPLE

Has the solution reached equilibrium?

What is the tendency of the solution?

Classification according to Langelier Index

Classification according to Ryznar Index

Treated sample 1

Treated sample 2

Treated sample 3

Treated sample 4

Treated sample 5

Treated sample 6

Conclusions:

Plot the pHs v,s pH values for the six treated samples + the original sample A. As a reference, draw a 45° line.

Observe the tendency and determine at what pH the solution would reach equilibrium.

Considering the amount of acid and base added, determine the amount of the corresponding substance required to reach equilibrium. For that purpose, draw a graph ofmL of acid and base added vs. pH.

mL of acid 0 mL of base

General conclusions:

Student Comments and Suggestions

Literature References

APHA/AWWA, Standard Methods for the Examination of Water and Wastewater, 18th ed.; Washington, 1992.

Sawyer, C. N.; McCarty, P. L.; Parkin, G. F. Chemistry for Environmental Engineering, 5th ed.; McGraw Hill: New York, 2003.

Stumm, W.; Morgan, J. J., Aquatic Chemistry: Chemical Equilibria and Rates in Natural Waters', 3rd ed.; Wiley Interscience: New York, 1996.

Vanderpool, D. "The pH Values for Cooling Water Systems", The Analyst 2004, 11 (2) Spring issue, http:// www.awt.org/members/publications/analyst/2004/ spring/the.ph_values.htm

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