Answer:
0.64 M
Explanation:
Given:
Volume of iron(II) solution (V₁) = 25.0 mL = 0.025 L
Molarity of iron(II) solution (M₁) = ?
Number of moles of iron(II) solution (n₁) = ?
Volume of dichromate solution (V₂) = 18.0 mL = 0.018 L
Molarity of dichromate solution (M₂) = 0.145 M
Number of moles of dichromate solution (n₂) = ?
Molarity is equal to the ratio of moles and volume.
So, molarity of dichromate solution is given as:
Now, let us write the complete balanced reaction for the given situation.
So, the complete balanced equation is given below.
From the equation, it is clear that, 1 mole of dichromate is required for 6 moles of iron(II) solution.
So, using unitary method, we find the number of moles of iron(II) solution.
1 mole of dichromate = 6 moles of iron(II)
∴ n₂ moles of dichromate = 6n₂ moles of iron(II)
= 
So, 0.016 moles of iron(II) is needed. Therefore, 
Now, molarity of iron(II) solution is given as:
Molarity = Moles ÷ Volume
Therefore, the molarity of the iron(II) solution is 0.64 M.
