Question

What mass of K2CO3 is needed to prepare 200. mL of a solution having a potassium ion concentration of 0.150 M

Answer 1

2.07 grams

Step-by-step explanation:

We know that the molecular mass of
`K_2CO_3` is 138.205 grams.

In order to find out how many grams we need to make 200 mL having a potassium ion concentration of 0.150, we need to find the number of moles first.

M = moles / liters

0.150 = x / 0.200

x = 0.03 moles

Since there are 2 potassium atoms in each molecule of
`K_2CO_3` so we will divide this number by half and multiply it by the molecular mass.

0.03/2 = 0.015 moles

Mass of
`K_2CO_3` needed = 0.015 × 138.205 = 2.07 grams