can someone check my answers here for my lab...
so i have 3.234*10-4 moles of ca2+ and mg2+ ions and used 0.02450L of edta so my molarity of both ions is 0.01320 M.
and now we had to find calcium, i used 0.01655 L of edta, can i use the same # of moles (3.234*10^-4) to find the molarity of calcium ???? idk how to find the moles of calcium
To find the molarity of calcium, you cannot directly use the same number of moles as you did for the combined calcium and magnesium ions. This is because the molar ratio between calcium and magnesium in the solution might be different.
To determine the moles of calcium, you need to know the stoichiometry of the reaction between the calcium ions (Ca2+) and EDTA. The stoichiometry represents the balanced equation for the reaction, which indicates the molar ratios between the reactants and products.
Assuming the reaction between calcium ions and EDTA is 1:1, which means one calcium ion reacts with one EDTA molecule, you would need to determine the number of moles of calcium:
Number of moles of calcium = Volume of EDTA solution used (in liters) × Molarity of EDTA solution
In your case, the volume of EDTA solution used is 0.01655 L and the molarity of EDTA solution is 0.01320 M. Therefore:
Number of moles of calcium = 0.01655 L × 0.01320 M = 0.00021786 moles of calcium
So, the number of moles of calcium is approximately 0.00021786 moles.
Please remember that this calculation assumes a 1:1 stoichiometry for the reaction. If the stoichiometry between calcium ions and EDTA is different, you would need to adjust the calculation accordingly.