# Chem EDTA and Molarity Question. Need help

• AMSAMS
In summary, the titration lab found that it took 0.005137 M of EDTA solution to titrate 100 mL of water.
AMSAMS
1. We had a titration lab where we titrated tap water with EDTA. Through our results we should be able to figure out the molarity of Ca and Mg ions. I think I'm doing this right but it seems to easy in comparison with everything else we are doing in lab and lecture so I just want to know if I'm missing something.

2. M=mol/L
MM of EDTA is 292.24g/mol
EDTA solution was prepared by dissolving 0.6005g of EDTA with 0.400L.
0.6005(g/mol)/292.24g=0.00205mol/.400L=0.005137M of EDTA soultion (I think)

3. 0.005137M*0.0290L (the amount it took to titrate the water)=1.474x10^-4 moles. There was 100.00mL of water and 0.50mL of a buffer added but I don't think the buffer volume is counted in the molarity. So, molarity would be
1.474x10^-4mol/100.00mL=1.474x10^-4M. This is for Mg and Ca

For just Ca, 0.005137*0.02175L (the amount it took to titrate the water) =1.117x10^-4 mol. There was 100.00mL of water and 0.50mL of a buffer added but I don't think the buffer volume is counted in the molarity. So, molarity would be
1.117x10^-4 mol/100.00mL=1.117x10^-4 M for Ca solution.

For just Mg: (1.474x10^-4M) - (1.117x10^-4M)= 3.57x10^-5M

Is that all there really is to this or am missing some extra step I should be doing because of the use EDTA?

AMSAMS said:
0.6005(g/mol)/292.24g=0.00205mol/.400L=0.005137M of EDTA soultion (I think)

Concentration is OK (assuming you used a pure, anhydrous EDTA - possible, but not the only option here). Just note you can't write moles=concentration, there should be no equal sign there.

0.0290L (the amount it took to titrate the water)

molarity would be
1.474x10^-4mol/100.00mL=1.474x10^-4M. This is for Mg and Ca

Sum of Mg & Ca, OK.

0.02175L (the amount it took to titrate the water)

That's where you have lost me. Just a moment ago you wrote it took 29.0 mL to titrate the water, so apparently you did here something different. I suppose this is result of titration at much higher pH, where Mg2+ is precipitated as Mg(OH)2. If so, your calculations look OK, just your description is wrong.

Disclaimer: I have not checked math, just the logic.

## 1. What is Chem EDTA and how is it used in science?

Chem EDTA (ethylene diamine tetraacetic acid) is a chelating agent commonly used in chemistry and biology experiments. It binds to metal ions, making them unavailable for reactions and allowing for more precise control over reactions. It is also used as a preservative in food and cosmetics.

## 2. How is molarity defined and calculated?

Molarity is a measure of concentration, specifically the number of moles of a substance per liter of solution. It is calculated by dividing the number of moles of solute by the volume of the solution in liters.

## 3. What is the role of EDTA in molarity calculations?

EDTA is often used as a standard in molarity calculations because it reacts with metal ions in a 1:1 ratio, making it easy to determine the concentration of a metal ion solution. It is also used to remove metal ions from solutions, allowing for more accurate molarity measurements.

## 4. How do you prepare a solution with a specific molarity using Chem EDTA?

To prepare a solution with a specific molarity using Chem EDTA, first determine the desired number of moles of EDTA needed. Then, calculate the mass of EDTA needed using its molar mass. Dissolve the calculated amount of EDTA in a known volume of solvent, usually water, to create the desired molarity solution.

## 5. What are some common uses of molarity and Chem EDTA in scientific research?

Molarity and Chem EDTA are commonly used in titration experiments to determine the concentration of a solution. They are also used in analytical chemistry to remove metal ions from samples for analysis. In addition, molarity and Chem EDTA are important in biochemical research for studying enzyme kinetics and protein binding.

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