Answer : The concentration of [tex]Fe^{3+}[/tex] after mixing is, [tex]6.0\times 10^{-4}M[/tex]
Explanation :
First we have to calculate the moles of [tex]Fe^{3+}[/tex] before mixing.
[tex]\text{Moles of }Fe^{3+}=\text{Concentration of }Fe^{3+}\times \text{Volume of }Fe^{3+}[/tex]
[tex]\text{Moles of }Fe^{3+}=0.00200M\times 0.003L=6.0\times 10^{-6}mol[/tex]
Now we have to calculate the total volume of solution after mixing.
Volume of solution = (3.00 + 4.00 + 3.00) mL
Volume of solution = 10.00 mL = 0.010 L
Now we have to calculate the concentration of [tex]Fe^{3+}[/tex] after mixing.
[tex]\text{Concentration of }Fe^{3+}=\frac{\text{Moles of }Fe^{3+}}{\text{Volume of solution}}[/tex]
[tex]\text{Concentration of }Fe^{3+}=\frac{6.0\times 10^{-6}mol}{0.010L}=6.0\times 10^{-4}M[/tex]
Thus, the concentration of [tex]Fe^{3+}[/tex] after mixing is, [tex]6.0\times 10^{-4}M[/tex]