# Homework Help: Is it possible to find uncertainty for water hardness?

1. May 9, 2007

### FlipStyle1308

1. The problem statement, all variables and given/known data
I am told to find the uncertainty for the titration part of determining the water hardness in my chemistry lab. I only have the following data:

By titrating 281.75 mL of titrant, it was determined that 532.08 ppm is the hardness of the water.

Also, for water remediation, my contaminant was fluoride, and my remediation agent was 0.005 M Ca(NO3)2 aqueous solution. What is the cheimcal equation describing remediation chemistry, and what is the remediation variable to be studied?

2. Relevant equations
No clue

3. The attempt at a solution
I cannot find any equations that will help me, since I do not have the "actual" value that I can use to determine uncertainty. If anyone is able to help me, it'd be great. Thanks!

Last edited: May 9, 2007
2. May 15, 2007

### chemisttree

Ca(NO3)2 <-------> Ca+2 + 2NO3-

Ca+2 + 2F- <---------> CaF2(s)

Ksp of CaF2 = [Ca+2][F-]^2 = 3.45 X 10^-11

Remediation variable = [F-]