Solution A homogeneous mixture of two or more substances. For Any Solution Solvent - the substance present in the most amount. Solute - the substance present in the least amount. For Any Solution Solvent - there can be only ONE Solute - there can be MORE than one Solvent - the substance present in the most amount. What is the solvent in air? Solute - the substance present in the least amount. Solvent - the substance present in the most amount. What are the solutes in air? Solute - the substance present in the least amount. Solvent - the substance present in the most amount. What is the solvent in stainless steel? Solute - the substance present in the least amount. Solvent - the substance present in the most amount. What are the solutes in stainless steel? Solute - the substance present in the least amount. Aqueous Solution Solvent - Water Solute - The substance dissolved in water Solubility The amount of solute that can be dissolved in a given amount of solvent, at a given temperature. QuickTime™ and a TIFF (Uncompressed) decompressor are needed to see this picture. QuickTime™ and a TIFF (Uncompressed) decompressor are needed to see this picture. Is NaCl soluble in H2O? QuickTime™ and a TIFF (Uncompressed) decompressor are needed to see this picture. Saturated Solution A solution containing the maximum amount of a solute that is possible to dissolve in a given volume of solvent at a given temperature. Saturated Solution NaCl has a solubility of 357 grams per liter of "cold" H2O. + Saturated Solution How many moles of NaCl are in the solution? NaCl solution Saturated Solution 357 g NaCl 1 mole NaCl = 58 g NaCl 6.2 mole NaCl NaCl solution Saturated Solution How many "particles" of NaCl are in the solution? NaCl solution Saturated Solution 23 10 357 g NaCl 6.02 X particles NaCl 58 g NaCl 24 10 3.7 X particles NaCl NaCl solution = Concentration A comparison of the amounts of solute and solvent in a solution. Concentration "Strong" and "Weak" give SOME comparison, but only a general idea. Concentration "Dilute" and "Concentrated" still don't provide enough for quantitative calculations. Concentration To do calculations, we must know "how much" solute and "how much" solvent are present. Molarity M = moles solute 3 dm solution 1 mole = formula mass (g) 1 liter = 1 cubic decimeter dm3 1 liter = 1000 milliliters 1 ml = 1 cm3 Molarity = moles dm3 1. What is the molarity of a liter of solution containing 100 grams of copper (II) chloride? Molarity = 100g CuCl2 1 liter moles dm3 Molarity = moles dm3 100g CuCl2 1 liter grams Molarity = 100g CuCl2 1 liter moles dm3 mole grams Molarity = 100g CuCl2 1 liter moles dm3 1 mole grams Molarity = 100g CuCl2 1 liter moles dm3 1 mole 134g Cu = 1 X 64 = 64 Cl = 2 X 35 = 70 134 Molarity = 100g CuCl2 1 liter moles dm3 1 mole 1 liter 134g 1 dm3 Molarity = 100g CuCl2 1 liter moles dm3 1 mole 1 liter 134g 1 dm3 Have we worked the problem? Molarity = 100g CuCl2 1 liter moles dm3 1 mole 1 liter 134g 1 dm3 .75M CuCl2 How is this problem different from the first? 2. How much NaCl is needed to prepare 250ml of 0.5M salt water The first ASKS for M 1. What is the molarity of a liter of solution containing 100 grams of copper (II) chloride? The second GIVES M 2. How much NaCl is needed to prepare 250ml of 0.5M salt water? 2.How much NaCl is needed to prepare 250 ml of 0.5 M salt water Preparation 250 ml 0.5 mole NaCl dm3 Preparation 250 ml 0.5 mole NaCl dm3 What units will we have when the problem is worked? Preparation 250 ml 0.5 mole NaCl dm3 need grams Preparation 250 ml 0.5 mole NaCl dm3 need grams Preparation 250 ml 0.5 mole NaCl dm3 1 mole NaCl need grams Preparation 250 ml 0.5 mole NaCl 58 g NaCl dm3 1 mole NaCl need grams Preparation 250 ml 0.5 mole NaCl 58 g NaCl dm3 1 mole NaCl Now What? need grams Preparation 250 ml 0.5 mole NaCl 58 g NaCl dm3 1 dm3 1 mole NaCl 1000 ml need grams Preparation 250 ml 0.5 mole NaCl 58 g NaCl dm3 1 dm3 1 mole NaCl 1000 ml 7.3 grams NaCl Practice Problems Practice Problem 1 0.37 g CaCl2 340 ml 1 mole 1000 ml 110 g 0.01 M CaCl2 1 dm3 Practice Problem 2 50 cm3 0.2 mole Al(OH)3 78 g Al(OH)3 dm 3 mole 0.78 g Al(OH)3 1 dm 3 1000 cm3 Homework Problems Homework Problem 1 50 g NaOH 200 cm3 1 mole 40 g 1000 cm3 1 dm3 6.25 M NaOH Homework Problem 2 100 cm3 0.25 mole CaSO4 dm3 3.4 g CaSO4 136 g mole 1 dm3 1000 ml Homework Problem 3 100 ml 0.5 mole HCl dm3 1.8 g HCl 36 g mole 1 dm3 1000 ml Making Dilutions Making Dilutions A solution can be made less concentrated by dilution with solvent Making Dilutions M 1 V1 = M 2 V2 original solution 1 = diluted solution 2 Volume units must be the same for both volumes in this equation. Dilution Problem How do you prepare 100ml of 0.40M MgSO4 from a stock solution of 2.0M MgSO4? Dilution Problem M1 V1 = M2 V2 M1 = M2 = V1 = V2 = Dilution Problem M1 V1 = M2 V2 M1 = 2.0M MgSO4 M2 = 0.40M MgSO4 V1 = unknown V2 = 100ml Dilution Problem Step 1 - write the equation: M1 V1 = M2 V2 Step 2 - manipulate the equation: V1 = M2 V2 /M1 Step 3 - add the numbers: V1 = (0.40M) (100ml) /2.0M Dilution Problem Step 4 - do the calculation: V1 = 20ml Step 5 - describe the preparation: Add 80ml of distilled water to 20ml of the 2.0 M MgSO4 solution Homework Problems Molarity Calculations: 1. 0.975M (NH4)2C4H4O6 2. 0.257M CoSO4 3. 0.291M Fe(NO3)2 Preparations: 1. 390g NiCl2 2. 95.3g AgF 3. Use 50cm3 of the 1.0M NaCl solution. Add 200cm3 of distilled water to make the total volume 250cm3. Dilutions: 1. Add 19.2cm3 of 0.52M CoCl2 solution to a graduate. Add distilled water to make the total volume 100cm3. 2. Add 72.5cm3 of 0.69M Ba(NO3)2 solution to a graduate. Add distilled water to make the total volume 200cm3. 3. Add 37.5ml of 2M NH4Br solution to a graduate. Add distilled water to make the total volume 500ml. Solution Preparation Other Solution Concentrations Molality m = moles solute Kg solvent Normality N = equivalents solute 3 dm solution