Question

10)Calculate the molarity of a potassium dichromate solution prepared by placing 9.67 g of K Cro in a

2 2 7
100-ml volumetric flask, dissolving, and diluting to the calibration mark.​

Answer 1

0.33 M

Step-by-step explanation:

From the question given above, the following data were obtained:

Mass of K₂Cr₂O₇ = 9.67 g

Volume of solution = 100 mL

Molarity =?

Next, we shall determine the number of mole in 9.67 g of K₂Cr₂O₇. This can be obtained as follow:

Molar mass of K₂Cr₂O₇ = (39×2) + (52×2) + (16×7)

= 78 + 104 + 112

= 294 g/mol

Mass of K₂Cr₂O₇ = 9.67 g

Mole of K₂Cr₂O₇ =?

Mole = mass /Molar mass

Mole of K₂Cr₂O₇ = 9.67 / 294

Mole of K₂Cr₂O₇ = 0.033 mole

Next, we shall convert 100 mL to litre (L). This can be obtained as follow:

1000 mL = 1 L

100 mL = 100 mL × 1 L / 1000 mL

100 mL = 0.1 L

Finally, we shall determine the molarity of the solution. This can be obtained as follow:

Mole of K₂Cr₂O₇ = 0.033 mole

Volume of solution = 0.1 L

Molarity =?

Molarity = mole / Volume

Molarity = 0.033 / 0.1

Molarity = 0.33 M

Thus, the molarity of the solution is 0.33 M