How many grams of potassium carbonate K2CO3 are needed to make 200 mL of a 2.5 M solution? Give me the number of moles then the number of grams.

Answer 1

Again, molarity = moles solute/liter solution.

2.5 M K₂CO₃ means you want 2.5 moles K₂CO₃ per liter of solution.

Since you only need 200 ml x 1 L/1000 ml = 0.200 liters, you can find the moles needed.

2.5 moles/L x 0.2 L = 0.50 moles K₂CO₃ needed to prepare 200 mls of solution that is 2.5 M

To find grams, use the molar mass of K₂CO₃ which is 138 g/mol

0.5 moles x 138 g/mol = 69 g K₂CO₃