I just need to know how to do it please, just give me formulas or something. But

Question

I just need to know how to do it please, just give me formulas or something. But here is all the data I have. I need to know how to determine the concentration of Calcium ions and Mg ions.

Sea Water Samples Titrating with Black T and Hydroxynaphthol blue 3 mL of pH 10 buffer and 6 drops of Eriochrome Black T Indicator 1 20.20 mL 2 21.30 mL 3 20.60 mL Blank 0.00 mL Value of Ca2+ + Mg2+ ~0.1 g of solid hydroxynaphthol blue 30 drops of 50 wt% NaOH Determination of Ca2+ ions 1 3.70 mL
2 3.40 mL 3 3.40 mL Blank 0.00 mL

Explanation / Answer

Strength of EDTA = f * 0.01 M

25 ml of Ca2+ + Mg2+ solution = V1 ml of EDTA

25 ml of Ca2+ solution = V2 ml of EDTA

1000 ml of 0.01 M EDTA = 1000 ml of 0.01 M Ca2+

= 0.40g of Ca2+

1ml of 0.01 M EDTA = 0.00040g of Ca2+

Amount of Ca2+ in 25 ml = 0.00040 * V2 * f

Amount of Ca2+ = 0.00040 * V2 * f * 40

Amount of Mg2+ in 25 ml = (V1 - V2)

1000 ml of 0.01 M EDTA = 1000 ml of 0.01 M of Mg2+

= 0.2432g of Mg2+

Ambunt of Mg2+ in 25 ml = 0.400243 * (V1 - V2) * f

.'. Amount of Mg2+ = 0.0002432 * (V1 - V2) * f * 40

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