Chemistry/Physical Setting Concentration of Solutions Br. Jabreal

Aim: How are concentrations of solutions expressed and calculated? Do Now: What does it mean if something is diluted? It means the concentration is reduced, usually by adding water. Ex. Adding water to juice increases the volume but not the amount of juice. It tastes less strong because the juice substances are less concentrated. Concentration: A measure of the quantity of solute dissolved in a given amount of solvent or solution.

Concentration Dilute solution contains small amount of solvent in given quantity of solvent. Concentrated solution contains large amount of solvent in given quantity of solvent

Molarity One way concentration is expressed is by molarity. Expresses amount of solute in moles per volume of solution in Liters.

Using Molarity Equation A solution has a volume of 250 mL and contains 0.70 mol NaCl. What is its molarity?

Using Molarity Equation How many moles of solute are needed to prepare 2.5 liters of 0.60 M solution?

Practice Intraveneous (IV) saline solutions are often administered to patients in the hospital. One saline solution contains 0.90 g NaCl in exactly 100 mL of solution. What is the molarity of this solution?

Practice Household laundry bleach is a dilute aqueous solution of sodium hypochlorite (NaClO). How many moles of solute are present in 1.5 L of 0.70M NaClO?

Mass Percent Composition Concentration can also be measured in terms of mass percent composition: *UNITS OF MASS MUST BE SAME FOR SOLUTE AND SOLUTION

Mass Percent Composition: Example A student dissolves 25.0 grams of glucose in 475 grams of water. What is the mass percent concentration of the glucose solution?

Practice A solution is made by dissolving 70.0 grams of KNO3(s) in 100. grams of water at 50oC and standard pressure. Show a numerical setup for calculating the percent by mass of KNO3 in the solution.

Parts per Million (PPM) Yet another way of expressing concentration is in parts per million (PPM). Often used to describe amount of pollutants in the air

PPM Example A certain gas has a concentration in water of 2 milligrams per 100 grams of water. What is the concentration of the gas in parts per million?

Practice A 2.5-gram sample of groundwater is found to contain 5.4 x 10-6 gram of Cu2+ ion. What is the ion concentration in parts per million?

Homework Chapter 16.2 Assessment Page 499 Questions 19, 20, (21 optional) Page 499 Question 60