Solution Concentration Molarity

Dilute vs. Concentrated Qualitative descriptions of a solution Weak solution few particles of solute in a solvent Strong Solution LOTS of solute particles dissolved in a solvent

Which is more concentrated? 5 mol in 1 L of solution or 1 mol in 5L of solution 2.5 mol in 2 L solution or 3.0 mol in 1.5L solution Which picture?

(M)olarity is the Quantitative measure of solution concentration number of moles of solute dissolved per liter of solution

What is the Molarity (M) of a solution if 37 What is the Molarity (M) of a solution if 37.0g of KCl is dissolved to make 250.0 mL of solution? Step 1 CONVERT 250.0mL .250L 37.0g of KCl to moles

Step 2 SUBSTITUTE into Formula

If you add water or evaporate it you will change the molarity of the solution Use this formula to determine the new molarity… M1V1 = M2V2

If a 5.0L solution is 2.0M and 1500.0 mL of water is added, what is the new (M)olarity? Step 1 MAKE a list and do any conversions M1 = 2.0 V1 = 5.0L M2=? V2= 1500mL 1.5L+ 5.0L = 6.5L In this problem….You have to add for the total solution volume

M1V1 = M2V2 (2.0M) (5.0L) = M2 (6.5L) 1.54M = new molarity STEP 2 SUBSTITUE and solve M1V1 = M2V2 (2.0M) (5.0L) = M2 (6.5L) 1.54M = new molarity

IF you want to make 500mL of a 1. 5M solution from a 12 IF you want to make 500mL of a 1.5M solution from a 12.0M solution, How much of the concentrated solution do you need and how much water do you need? M1 = 1.5M V1 = 500mL M2=12M V2= ? M1V1 = M2V2 (1.5)(500) = (12)V2 V2 = 62.5mL Ask yourself…..what does this volume represent????

This represents the volume of the concentrated solution (12M) you need. But I need 1.5M and 500mL of it….how do I get there? To go from 12M to 1.5M you have to add water. But how much water???? Let’s draw a diagram to find out.

62.5mL of 12M 500mL of 1.5M TOTAL Vol you WANT Vol you have 500mL – 62.5mL = 437.5mL Vol you need to ADD

Molarity Practice M1V1 = M2V2

THE END