2. A solution of I2 was standardized with ascorbic acid. Using a 0.1000-g sample of pure ascorbic acid, 25.32 mL of I2 were required to reach the starch end point.
a) What is the molarity of the iodine solution?
To calculate the molarity of the iodine solution, we need to first determine the number of moles of ascorbic acid reacted with the iodine. Let's break down the steps to find the answer:
Step 1: Determine the number of moles of ascorbic acid (C6H8O6):
Given that the mass of ascorbic acid used is 0.1000 g, we need to calculate the number of moles:
Molar mass of ascorbic acid (C6H8O6) = 176.12 g/mol
Number of moles of ascorbic acid = mass / molar mass = 0.1000 g / 176.12 g/mol
Step 2: Calculate the molarity of the iodine solution:
Given that 25.32 mL of the iodine solution was required to react with the ascorbic acid, we can use the balanced equation between iodine and ascorbic acid to determine the moles of iodine reacted.
The balanced equation is:
C6H8O6 + I2 → C6H6O6 + 2HI
From the balanced equation, we know that 1 mole of ascorbic acid reacts with 1 mole of iodine. Therefore, the moles of iodine reacted is the same as the moles of ascorbic acid.
Step 3: Calculate the molarity of the iodine solution:
Molarity (M) is defined as moles of solute divided by the volume of solution in liters.
Molarity (M) = moles of iodine / volume of iodine solution (in liters)
To convert the volume of iodine solution from milliliters (mL) to liters (L), divide by 1000.
Now we can put it all together:
Moles of ascorbic acid = 0.1000 g / 176.12 g/mol
Moles of iodine = Moles of ascorbic acid
Volume of iodine solution = 25.32 mL / 1000 = 0.02532 L
Molarity (M) = Moles of iodine / Volume of iodine solution
Molarity (M) = Moles of ascorbic acid / Volume of iodine solution
Molarity (M) = (0.1000 g / 176.12 g/mol) / 0.02532 L
Calculate the value to find the molarity of the iodine solution.
1 mol ascorbic acid reacts with 1 mol I2 so the ratio is 1:1.
mols ascorbic acid = grams/molar mass = ?
mols I2 = mols ascorbic acid from the equation.
M I2 = mols I2/L I2.