How many Milligrams of potassium chloride KCl are required to make a 15 mL of a 1.20 M solution?

1340 mg

Explanation:

concentration is the number of moles of solute in a 1000 mL of solution

the concentration of KCl solution is 1.20 M

There are 1.20 mol in 1000 mL of solution

a volume of 1000 mL contains - 1.20 mol

therefore 15 mL solution contains - 1.20 mol / 1000 mL x 15 mL = 0.018 mol

the molar mass of KCl is - 74.5 g/mol

mass of 1 mol is - 74.5 g

therefore mass of 0.018 mol is - 74.5 g/mol x 0.018 mol = 1.34 g

1000 mg - 1 g

therefore 1.34 g in milligrams is - 1.34 g x 1000 mg/g = 1340 mg