Question

How much potassium permanganate (KMnO4) should you weigh out in order to prepare 0.50L of a 3.5M solution? The molar mass of KMnO4 is 158g/mol.

a) 1.8 mol
b) 280 g
c) 7.0 mol
d) 350 g

Answer 1

To prepare a 0.50L of a 3.5M solution of potassium permanganate (KMnO4), you should weigh out approximately 280g of KMnO4.

Step-by-step explanation:

To calculate the amount of potassium permanganate (KMnO4) needed to prepare a 0.50L solution with a concentration of 3.5M, we can use the formula:

Amount of KMnO4 (in mol) = Concentration (M) x Volume (L)

Plugging in the given values, the calculation is:

Amount of KMnO4 = 3.5M x 0.50L = 1.75 mol

Now, we can calculate the mass of KMnO4 using the molar mass:

Mass = Amount of KMnO4 (mol) x Molar mass (g/mol)

Mass = 1.75 mol x 158g/mol = 276.5g (approximately 280g)

Therefore, the correct answer is option b) 280g.