How to calculate the normality of sodium thiosulphate in this titration. The volume of sodium thiosulphate used at the endpoint is 24ml.
The Correct Answer and Explanation is :
To calculate the normality of sodium thiosulfate (Na₂S₂O₃) in a titration, you will need to know the amount of the substance with which it reacts, usually expressed through its equivalent weight, and the volume of Na₂S₂O₃ solution used to reach the endpoint. Here’s how you can calculate it:
- Volume of Sodium Thiosulfate Used: Given as 24 mL or 0.024 liters.
- Reaction Information: The reaction commonly involves iodine (I₂) being titrated with sodium thiosulfate. The balanced chemical equation for this reaction is: I2+2Na2S2O3→2NaI+Na2S4O6I₂ + 2 Na₂S₂O₃ → 2 NaI + Na₂S₄O₆ This equation tells us that 1 mole of iodine reacts with 2 moles of sodium thiosulfate.
- Mole Ratio: Since the reaction ratio between I₂ and Na₂S₂O₃ is 1:2, the equivalent weight of Na₂S₂O₃ is half its molar mass (because 1 mole of I₂ requires 2 moles of Na₂S₂O₃).
- Calculation of Normality: Normality (N) = Number of equivalents of soluteVolume of solution in liters\frac{\text{Number of equivalents of solute}}{\text{Volume of solution in liters}} An equivalent of Na₂S₂O₃ in this reaction corresponds to its ability to react with 1 mole of iodine (since 2 moles of Na₂S₂O₃ react with 1 mole of I₂). Assuming you know the molarity of iodine (or can calculate it based on the amount used), you can calculate the normality of Na₂S₂O₃ by multiplying the molarity of the iodine solution by 2 (because each mole of iodine reacts with 2 equivalents of Na₂S₂O₃). For example, if 0.1 M of I₂ is used: Normality of Na₂S₂O₃=2×Molarity of I₂\text{Normality of Na₂S₂O₃} = 2 \times \text{Molarity of I₂} Normality of Na₂S₂O₃=2×0.1=0.2 N\text{Normality of Na₂S₂O₃} = 2 \times 0.1 = 0.2 \text{ N} However, without the molarity of the iodine solution used in your titration, we can’t compute the exact normality of Na₂S₂O₃. It’s essential to either know or be able to calculate the molarity of the iodine for a precise calculation.
Conclusion: Calculating the normality in a titration requires understanding the stoichiometry of the reaction involved. For sodium thiosulfate titrations involving iodine, remember that the normality is double the molarity of the iodine solution due to the 1:2 stoichiometric reaction ratio. This calculation method assumes accurate measurement of reaction components and complete reaction according to the stoichiometry.
I’ll now create an image that visually represents this calculation process for better understanding.
Here is the visual representation of a chemistry lab setup for a titration experiment, showing the process of adding sodium thiosulfate to an iodine solution. This image illustrates the careful measurement and observation involved in determining the endpoint of the titration, which is critical for accurate calculation of the normality.
