2 What is different between the glasses of Kool-aid?
3 Solution concentration can be described generally Dilute - reduced in strength, weak, watered down.Concentrated – stronger, pure. Has less water.
4 What is the problem with just using dilute and concentrated as descriptions of the solution concentration?
5 Is solution B dilute or concentrated? The terms dilute and concentrated are relative.Scientists need a more precise way of referring to the concentration of a solution.ConcentratedDiluteSolution A Solution B Solution C
6 Solution concentration can be described specifically Do you remember the “mole” from Stoichiometry?What is a mole?How might you use it to describe the concentration of a solution?
7 Concentration can be represented by… MolarityMolalityPercent by MassWe will learn about this calculation later on.
8 The ratio of the moles of solute to the volume of solution in liters. MolarityThe ratio of the moles of solute to the volume of solution in liters.Moles of soluteMolarity (M) =Volume in Liters of solutionUsed for most chemistry calculations of concentration
9 Molality Molality = moles of solute per kg solvent Moles of solute kilogram of SolventUsed for chemistry when volume of solvent is not constant
10 Percent by MassPercent by Mass = mass of solute divided by mass of total solutionMass (g) of solute% by mass =Mass of Solvent + Mass of SoluteUsed for food, medicine, household cleaners and chemicals
11 How to Calculate Dilutions Using molarity to calculate dilutions is EASY.Moles stays the sameVolume changesMolarity changesM1V1 = M2V2Re-arrange to solve for the requested information
12 How to read Molarity 6.0 M NaCl Read: “6 molar solution of NaCl” Can be abbreviated 6M solutionYou must be careful to label the molarity with a capital M so that it is not confused with m for molality.
13 How to make a solution using molarity (6M NaCl) (a) Add 6 moles NaCl to the volumetric flask. How would you measure that?6moles NaCl g NaCl1 mole NaCl= 351 g NaCl
14 How to make a solution using molarity (6M NaCl) (b) Add dH2O to dissolve and mix the NaCl(c) Fill the flask with dH2O until you reach the 1000mL line.
15 Types of Calculations with Molarity: 1. Finding concentration of a solution. 2. Finding the mass of solute needed. 3. Finding the volume of solution made.
16 Finding Concentration Antifreeze is a solution of ethylene glycol, C2H6O2 in water. If 4.50 L of antifreeze contains 27.5 g of ethylene glycol, what is the concentration of the solution?27.5 g C2H6O21 mol C2H6O262.08 g C2H6O24.5 L= mol/L orM C2H6O2
17 Finding MassWhat mass of sodium carbonate, Na2CO3, is present in 50 ml of a 0.750M solution?Conversion Factor50 ml1 L0.750 molg Na2CO31000 mL1 L1 mol Na2CO3= 3.97 g Na2CO3
18 Finding VolumeConversion FactorWhat volume of 1.50 mol/L HCl solution contains 10.0 g of hydrogen chloride?10.0 g HCl1 mol HCl1 L36.46 g HCl1.50 mol= L or 183 mL