6. M = Molarity n = moles You need these three variables in every problem. L = Liters M = n/L n = ML L = n/M Does the question give you grams? Convert grams to moles (n). Find molar mass of the compound. Divide grams given by molar mass to get moles (n). Does the question give you mL? Convert to Liters. Move the decimal three places to the left. DO NOT ROUND UNTIL THE END. Round everything to the 100th. Ex: 45 = 45.00, 65.432 = 65.43, 8.767 = 8.77 Don’t forget to LABEL.
7. Calculating Molarity Sample Problem What is the molarity of a potassium chloride solution that has a volume of 400.0 mL and contains 85.0 g KCl?
8. Sample Problem Solution volume of solution = 400.0 mL mass of solute = 85.0 g KCl molarity of KCl solution = ?
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