Answer:
0.0038 M
Explanation:
Hardness of the water is generally due to the presence of [tex]CaCO_3[/tex] in water.
At equivalence point
Moles of [tex]Ca^{2+}[/tex] = Moles of EDTA
Considering
[tex]Molarity_{Ca^{2+}}\times Volume_{Ca^{2+}}=Molarity_{EDTA}\times Volume_{EDTA}[/tex]
Given that:
[tex]Molarity_{EDTA}=0.020\ M[/tex]
[tex]Volume_{EDTA}=4.86\ mL[/tex]
[tex]Volume_{Water\ or\ Ca^{2+}}=25.00\ mL[/tex]
So,
[tex]Molarity_{Ca^{2+}}\times 25=0.020\times 4.86[/tex]
[tex]Molarity_{Ca^{2+}}=0.0038\ M[/tex]
