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11. Iodine is required for a healthy diet - Scottish Highers Chemistry - Question 11 - 2018
Question 11
11. Iodine is required for a healthy diet. Food grown in certain parts of the world is low in iodine. To prevent iodine deficiency in people's diets, table salt can ... show full transcript
Worked Solution & Example Answer:11. Iodine is required for a healthy diet - Scottish Highers Chemistry - Question 11 - 2018
Step 1
Describe a procedure to accurately weigh out a 50.0 g sample of iodised table salt.
Answer
To accurately weigh a 50.0 g sample of iodised table salt, use a balance calibrated to the required accuracy. Begin by placing a clean and dry weighing boat or paper on the balance and tare it to zero. Then, carefully add the iodised salt until the balance reads 50.0 g. Make sure to add the salt slowly and to watch for overshooting the target weight. Once you achieve the desired mass, note the weight and remove the weighing boat without losing any salt.
Step 2
Step 3
Calculate the average volume, in cm³, of sodium thiosulfate solution that should be used to determine the number of moles of iodine released.
Answer
To calculate the average volume of sodium thiosulfate used in the titrations, sum the volumes from each sample and divide by the number of samples:
ext{Average Volume} = rac{(10.0 + 9.4 + 9.6)}{3} = 9.67 ext{ cm}^3
Step 4
Calculate the number of moles of iodine released from 50 cm³ of the standard salt solution.
Answer
Using the average volume from the previous part, we can find the number of moles of iodine released. The molarity of the sodium thiosulfate solution is 0.0010 mol/L. The moles of iodine can be calculated using:
ext{Moles of I}_2 = ext{Molarity} imes ext{Volume (L)} = 0.0010 imes rac{9.67}{1000} = 9.67 imes 10^{-6} ext{ moles}