Water Hardness Lab

Topics: Calcium carbonate, Water, Hard water Pages: 3 (711 words) Published: October 16, 2012
Water Hardness

I. Objective:

Most water in nature contains some kinds of ions, which harden the water, specifically in this case is Ca2+. A small amount of minerals is good for our health but a lot would cause harm to our daily water usages. (film on glass shower doors, shower walls, bathtubs, sinks, faucets,etc) This lab allows us to determine the hardness of different types of water by titration using a standardized EDTA solution. Furthermore, the lab also helps to prove the efficiency of the Water Filter.

II. Discussion:

1. Titration 1:
Solubility of Calcium Carbonate in ppm: 114.80 ppm
Solubility of Calcium Carbonate calculated using Ksp: 7.05 ppm There is a big difference between two numbers because of two possible reasons:
_ The filtration process possibly went not as accurate as It should.
_ I heated the water while dissolving CaCO3, and that made it more soluble.
_ The errors came from the titration, due to the fact that the color change of the solution is not easy to define. (Purple to blue) I might have put too much titrant into the solution, and that would cause a difference.

2. Water hardness is a water quality that demonstrates the quantity of minerals in certain water sample. The bigger the amount of minerals present, the harder that water will be.

Minerals responsible for making water hard are primarily: Calcium and Magnesium. These minerals usually exist in form of salts in the ground, which are soluble in water/acid. Therefore, the salts react with water or rain (slightly acidic), the salt dissolve and the ions are now present in the water. It’s to say the minerals are carried to the water from the ground.

PPM is parts per million.

3. Water hardness is the measurement of [Ca2+ ] in the water sample. Using a known amount of standardized EDTA to titrate a known amount of water sample, we could easily find the [Ca2+ ] (in ppm), which is the hardness of water.

From a titration point of view,...
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