In a precipitation reaction between FeCl2(aq) and LiOH(aq), 11.6 mL of 0.210 M FeCl2(aq) completly reacted with 35.1 mL of LiOH(aq). What was the molarity of LiOH(aq)? FeCl2(aq) + 2 LiOH(aq) → Fe(OH)2(s) + 2 LiCl(aq)

Answer :

Answer: The molarity of LiOH is 0.139 M

Explanation:

To calculate the number of moles for given molarity, we use the equation:

[tex]\text{Molarity of the solution}=\frac{\text{Moles of solute}}{\text{Volume of solution (in L)}}[/tex]     .....(1)

Molarity of iron (II) chloride solution = 0.210 M

Volume of solution = 11.6 mL = 0.0116 L   (Conversion factor: 1 L = 1000 mL)

Putting values in equation 1, we get:

[tex]0.210M=\frac{\text{Moles of }FeCl_2}{0.0116L}\\\\\text{Moles of }FeCl_2=(0.210mol/L\times 0.0116L)=2.44\times 10^{-3}mol[/tex]

For the given chemical reaction:

[tex]FeCl_2(aq.)+2LiOH(aq.)\rightarrow Fe(OH)_2(s)+2LiCl(aq.)[/tex]

By Stoichiometry of the reaction:

1 mole of iron (II) chloride reacts with 2 moles of LiOH

So, [tex]2.44\times 10^{-3}mol[/tex] moles of iron (II) chloride will react with = [tex]\frac{2}{1}\times 2.44\times 10^{-3}=4.88\times 10^{-3}mol[/tex] of LiOH

Calculating the molarity of LiOH by using equation 1:

Moles of LiOH = [tex]4.88\times 10^{-3}mol[/tex]

Volume of LiOH = 35.1 mL = 0.0351 L

Putting values in equation 1, we get:

[tex]\text{Molarity of LiOH}=\frac{4.88\times 10^{-3}mol}{0.0351L}=0.139M[/tex]

Hence, the molarity of LiOH is 0.139 M

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