HELP EDTA reacts with Ca2+ in a 1:1 mole ratio..... What is the concentration of the calcium ions solution? ?

Question 5
Ca²⁺(aq) + EDTA(aq) → Ca²⁺-EDTA
Mole ratio Ca²⁺ : EDTA = 1 : 1

Moles of EDTA reacted = (0.5 mol/L) × (20.8/1000 L) = 0.0104 mol
Moles of Ca²⁺ ions = Moles of EDTA reacted = 0.0104 mol
Concentration of Ca²⁺ ions = (0.0104 mol) / (103/1000 L) = 0.1010 M

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OR:

(0.5 mol EDTA / 1000 mL EDTA solution) × (20.8 EDTA solution) × (1 mol Ca²⁺ ions / 1 mol EDTA) / (103/1000 L Ca²⁺ solution)
= 0.1010 M Ca²⁺ ions