[Wilflife_Biology100]

Hi guys,
I am an undergraduate student on a wildlife biology course and one of my semester 1 modules is chemistry. On Friday, I did a practical on determining the water hardness of water through titration with ethylene diamine tetra-acetic acid. I have included the results of my experiment in a picture with the relevant concentrations of the chemicals used. I also indicated which indicators were used. I have also included a picture of the question I am stuck on (Question 1). I am finding it difficult to do the calculations using the results obtained. May have got the total water hardness but I don't trust the rest of my answers. Hope you can help. Thank You https://imgur.com/a/Ei85ZoM https://imgur.com/a/sXbFiLD

[chenbeier]

You have to figure out how much mole Calcium correspondes to the hardness.
With your values of the titration you can calculate it.

[Wilflife_Biology100]

You have to figure out how much mole Calcium correspondes to the hardness.
With your values of the titration you can calculate it.

How do I figure the number of moles out? Thank you

[chenbeier]

1 ml 0,01 M EDTA-solution  =   0,01 mmol Ca²⁺ =  0,56 mg CaO 

What was the molarity of your solution?

Check what is the definition of hardness in your country. Maybe 10 mg CaO = 1° Hardness?

http://www2.vernier.com/sample_labs/WQV-14-COMP-total_water_hardness.pdf

[Wilflife_Biology100]

I’ve no idea. It was just a hard eater solution made by a lecturer, didn’t have any molarity on it

[chenbeier]

If you have no futher information then your work was useless.
Describe what you have and what you have done.

[Borek]

Beware: you were asked about the concentration of the EDTA solution, not the Ca/Mg solution. EDTA solution concentration is given in your notes.

Start with the reaction equation. How do the Ca²⁺ and/or Mg²⁺ reactwith EDTA?