This is for a science study at school. I bought my 2 liquid test kit from GoLanTec. The procedure is as follows: add 2 drops of solution a to 7.5 ml of water (then shake). The water turns pink. A few drops of solution b are then added via titration until the color change from pink to blue (shake after each drop). The number of drops is the hardness in °dH. Multiplying by 1.78 gives the hardness in French degrees.
Can someone tell me which 2 liquids are in this because this is important for my research?
Answer
Hi Jolien
The hardness of water is often determined by titration. The calcium and magnesium ions, which cause the hardness, react with EDTA to form a complex. To see if all the ions have reacted, add an indicator that changes color when all the metal ions have been used up.
Solution a is therefore normally the indicator (often eriochrome-T) and solution b is a solution of EDTA (or other complexing product).
You will also find sufficient information about this provision on the internet.
Kind regards
Answered by
Dr Marina Vanhecke
analytical chemistry toxicology soil remediation
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