The amount of I − 3 ( aq ) in a solution can be determined by titration with a solution containing a known concentration of S 2 O 2 − 3 ( aq ) (thiosulfate ion). The determination is based on the net ionic equation 2 S 2 O 2 − 3 ( aq ) + I − 3 ( aq ) ⟶ S 4 O 2 − 6 ( aq ) + 3 I − ( aq ) Given that it requires 29.4 mL of 0.380 M Na 2 S 2 O 3 ( aq ) to titrate a 30.0 mL sample of I − 3 ( aq ) , calculate the molarity of I − 3 ( aq ) in the solution.

Respuesta :

Answer:

The molarity of I₃⁻ (aq) solution: M₂ = 0.186 M

Explanation:

Given net ionic equation:  

2S₂O₃²⁻ (aq) + I₃⁻ ( aq ) ⟶ S₄O₆²⁻ (aq) + 3I⁻ (aq)

Number of moles of S₂O₃²⁻: n₁ = 2, Number of moles of I₃⁻: n₂ = 1

Given- For S₂O₃²⁻ solution: Molarity: M₁ = 0.380 M, Volume: V₁ = 29.4 mL;

For I₃⁻ (aq) solution: Molarity: M₂ = ? M, Volume: V₂ = 30.0 mL

         

To calculate the molarity of I₃⁻ (aq) solution, we use the equation:

[tex]\frac{M_{1}V_{1}}{n_{1}}=\frac{M_{2}V_{2}}{n_{2}}[/tex]

[tex]\frac{(0.380 M)\times (29.4 mL)}{2}=\frac{M_{2}\times (30.0 mL)}{1}[/tex]

[tex]\Rightarrow M_{2} = \frac{(0.380 M)\times (29.4 mL)}{(30.0 mL)\times 2} = 0.186 M[/tex]

Therefore, the molarity of I₃⁻ (aq) solution: M₂ = 0.186 M

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