What is the molarity of a solution composed
of 2.23 g of potassium iodide (KI) dissolved in
enough water to make 0.181 L of solution?
Answer in units of M
mols KI = grams/molar mass
Then M = mols/L solution.
To find the molarity (M) of a solution, you need to know the number of moles of solute and the volume of the solution in liters.
1. Start by calculating the number of moles of potassium iodide (KI) using its molar mass. The molar mass of KI is the sum of the atomic masses of potassium (K) and iodine (I).
The atomic mass of K = 39.10 g/mol
The atomic mass of I = 126.90 g/mol
Molar mass of KI = (39.10 g/mol) + (126.90 g/mol) = 166.00 g/mol
2. Next, use the given mass of KI (2.23 g) and its molar mass to determine the number of moles. Divide the mass of KI by its molar mass:
Moles of KI = 2.23 g / 166.00 g/mol
3. Calculate the volume of the solution in liters using the given value of 0.181 L.
4. Finally, divide the moles of KI by the volume of the solution to get the molarity:
Molarity (M) = Moles of KI / Volume of solution (in liters)
Now, plug in the values to calculate the molarity.