Question

In a sample consisting of 1.00 mol nabr and 0.300 mol ki, what is the mass percent of iodine? (a) 24.9% (b) 32.6% (c) 47.2% (d) 83.1

Answer 1

To find the mass percent of iodine in the sample, calculate the mass of iodine and the total mass of the sample. The mass percent can be calculated using the formula: Mass percent of iodine = (Mass of iodine / Total mass of sample) x 100%. The mass percent of iodine in the sample is 47.2%.

Step-by-step explanation:

To find the mass percent of iodine in the sample, we need to calculate the mass of iodine and the total mass of the sample. We can use the equation:

Mass percent of iodine = (Mass of iodine / Total mass of sample) x 100%

To calculate the mass of iodine, we need to know the molar mass of iodine (I₂), which is 253.8 g/mol. The mass of iodine in the sample can be calculated by multiplying the number of moles of iodine by its molar mass.

The number of moles of iodine in the sample can be calculated using the mole ratio between KI and I₂ in the balanced chemical equation:

2 KI + I₂ -> 2 K + 2 I₂

From the equation, we can see that 4 moles of iodine are produced for every 4 moles of KI. Therefore, the number of moles of iodine in the sample is equal to the number of moles of KI.

Now, we can calculate the mass percent of iodine by substituting the mass and moles of iodine into the formula. The answer is (c) 47.2%.

Answer 2

The quantities you have to know are the molar masses and the molecular stoichiometric ratios. The solution for this problem is as follows:

Mass Percent of Iodine = (Mass of Iodine/Mass of NaBr and KI)*100

Mass of NaBr = 1 mol NaBr * 102.89 g/mol = 102.89 g
Mass of KI = 0.3 mol KI * 166 g/mol = 49.8 g
Mass of KI = 0.3 mol KI * 1 mol I/1mol KI * 1 mol I₂/2 mol I * 253.81 g/mol = 38.07 g

Mass %I₂ = 38.07/(102.89+49.8) * 100 = 24.9%