Question

A chemist prepares a solution of potassium permanganate KMnO4 by measuring out 3.7 μmol of potassium permanganate into a 50 mL volumetric flask and filling the flask to the mark with water. Calculate the concentration in mol/L of the chemist's potassium permanganate solution. Round your answer to 2 significant digits.

a) 0.07 mol/L
b) 0.15 mol/L
c) 0.08 mol/L
d) 0.07 μmol/L

Answer 1

The concentration of the potassium permanganate solution is 0.074 mM, calculated by converting 3.7 µmol KMnO4 into moles and then dividing by the volume of the solution in liters.

Step-by-step explanation:

To calculate the concentration of the potassium permanganate solution, we first need to convert the volume from milliliters to liters and then use the formula for molarity:

Molarity (M) = Moles of solute (mol) / Volume of solution (L)

First, we convert the volume of the solution to liters:

50 mL = 0.050 L

Next, we know that the chemist measured out 3.7 µmol of potassium permanganate. To convert this to moles, we use the fact that 1 mol = 10^6 µmol:

3.7 µmol KMnO4 = 3.7 x 10^-6 mol KMnO4

Now, we use the molarity formula:

Molarity = 3.7 x 10^-6 mol / 0.050 L = 7.4 x 10^-5 mol/L

Since we have to round our answer to 2 significant digits, the molarity of the potassium permanganate solution is:

0.074 x 10^-3 mol/L or 0.074 mM

The correct answer from the options provided is therefore:

0.074 mM (which is not listed in the answer choices provided, suggesting a possible typo or miscalculation in the provided options).