Question

You need to make an aqueous solution of 0.194 M potassium acetate for an experiment in lab, using a 125 mL volumetric flask. How much solid potassium acetate should you add

Answer 1

To prepare 0.194 M potassium acetate, add 2.379895 g of potassium acetate to a 125 mL volumetric flask and fill with water to the mark.

Define molarity of a solution.

Molarity (M) is the amount of a substance in a certain volume of solution. Molarity is defined as the moles of a solute per litres of a solution.

The following data were obtained from the question:

Molarity of potassium acetate = 0.194 M

Volume of solution = 125 mL

Mass of potassium acetate =?

Next, we shall convert 125 mL to L. This can be obtained as follow:

1000 mL = 1 L

Therefore,

125 mL = 0.125 L

Thus, 125 mL is equivalent to 0.125 L.

Next, we shall determine the number of moles of potassium acetate in the solution. This can be obtained as follow:

Molarity of potassium acetate = 0.194 M

Volume of solution = 0.125 L

Moles of potassium acetate =?

Molarity = $\frac{mole}{Volume}$

Cross multiply

Mole of potassium acetate = 0.194 M × 0.125

Mole of potassium acetate = 0.02425 mole

Finally, we shall determine the mass of potassium acetate

Molar mass of potassium acetate= 98.14 g/mol

Mass of potassium acetate =?

Mole = $\frac{mass}{Molar mass}$

Mass of potassium acetate =0.02425  × 98.14

Mass of potassium acetate = 2.379895 g

Thus, to prepare 0.194 M potassium acetate, add 2.379895 g of potassium acetate to a 125 mL volumetric flask and fill with water to the mark.

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