1 Some Definitions A solution is a _______________ mixture of 2 or more substances in a single phase. One constituent is usually regarded as the SOLVENT and the others as SOLUTES.

2 Parts of a Solution SOLUTE – the part of a solution that is being dissolved (usually the lesser amount) SOLVENT – the part of a solution that dissolves the solute (usually the greater amount) Solute + Solvent = Solution SoluteSolventExample solid liquid gassolid liquid gasliquid gas

3 Definitions Solutions can be classified as saturated or unsaturated. A saturated solution contains the maximum quantity of solute that dissolves at that temperature. An unsaturated solution contains less than the maximum amount of solute that can dissolve at a particular temperature

4 Definitions SUPERSATURATED SOLUTIONS contain more solute than is possible to be dissolved Supersaturated solutions are unstable. The supersaturation is only temporary, and usually accomplished in one of two ways: 1.Warm the solvent so that it will dissolve more, then cool the solution 2.Evaporate some of the solvent carefully so that the solute does not solidify and come out of solution.

5 Supersaturated Sodium Acetate Supersaturated Sodium Acetate One application of a supersaturated solution is the sodium acetate “heat pack.”One application of a supersaturated solution is the sodium acetate “heat pack.”

6 Homework Read section 8.5 Pages Page 395 #1-3 Page 397 #1-4,6

7 IONIC COMPOUNDS Compounds in Aqueous Solution Many reactions involve ionic compounds, especially reactions in water — aqueous solutions. KMnO 4 in water K + (aq) + MnO 4 - (aq)

8 How do we know ions are present in aqueous solutions? The solutions _______________ __________ They are called ELECTROLYTES HCl, MgCl 2, and NaCl are strong electrolytes. They dissociate completely (or nearly so) into ions. Aqueous Solutions

9 Some compounds dissolve in water but do not conduct electricity. They are called nonelectrolytes. Examples include: sugarethanol ethylene glycol Examples include: sugarethanol ethylene glycol

10 Laboratory Concentration of Solutions The amount of solute in a solution is given by its concentration The amount of solute in a solution is given by its concentration. Molarity (C) = moles solute(n) litres of solution(V) Units for molarity are mol/L also written as mol L -1 and M

11 PROBLEM: Dissolve 5.00g of NiCl 2 6 H 2 O in enough water to make 250 mL of solution. Calculate the molar concentration. Step 1: Calculate moles of NiCl 2 6H 2 O Step 2: Calculate Molarity NiCl 2 6 H 2 O [NiCl 2 6 H 2 O ] = M

12 Try this problem 25.0 g of NaCl is dissolved in mL of water. Find the molar concentration of the resulting solution. C = n/V 25.0 g NaCl 58.5 g/mol NaCl = mol NaCl C = n/V mol NaCl L = M NaCl Convert volume to L ml  L divide by 1000 Convert mass of solute to moles mL = 5.000L

13 Step 1: Change mL to L. 250 mL = L Step 2: Calculate moles using n = CV. Moles = ( mol/L) (0.250 L) = moles Step 3: Convert moles to mass. ( mol)(90.00 g/mol) = 1.13 g USING MOLARITY Moles(n) = CV What mass of oxalic acid, H 2 C 2 O 4, is required to make 250. mL of a M solution?

14 Learning Check How many grams of NaOH are required to prepare 400. mL of 3.0 M NaOH solution? 1)12 g 2)48 g 3) 300 g

15 Using Molarity Cont. What volume of solution would contain 42.6g of sucrose with concentration of 0.525M? V = n/C Convert mass to moles Moles = 42.6g / 342 g/mol = moles Moles = 42.6g / 342 g/mol = moles V = n/C V= mol/0.525M = 0.237L

16 Practice Page 400 #1-4