Regents Chemistry Unit 3C Solutions Text Chapter 13 Reference Tables F, G & T. Chemists have Solutions!

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1 Regents Chemistry Unit 3C Solutions Text Chapter 13 Reference Tables F, G & T Chemists have Solutions!

2 SOLUTIONS homogeneous mixture (uniform composition throughout) Solute - substance being dissolved (usually present in the lesser amount) Solvent does the dissolving - present in greater amount

3 Types of Solutions 1) Gas - both solvent/solute are gases ex. Air 2) Solids - 2 or more solids are uniformly spread out ex. alloy- ex. brass = Cu/Zn; steel = iron + carbon 3) Aqueous water is the solvent, (aq) ex. NaCl(aq) 4) Liquid ex. antifreeze

4 Types of Solutions Con t Miscible ex. Rubbing alcohol and water Immiscible ex. Oil and water

5 Solubility the ability to dissolve in water UNSATURATED SOLUTION more solute dissolves SATURATED SOLUTION no more solute dissolves SUPERSATURATED SOLUTION becomes unstable, crystals form concentration Precipitation Dissolved material falling out of solution

6 shows the dependence of solubility on temperature Solubility Curves

7 Solubility maximum grams of solute that will dissolve in 100 g of solvent at a given temperature varies with temp based on a saturated solution

8 Saturation A solution that contains the maximum amount of solute that may be dissolved under existing conditions is saturated. *This is a solution that is at equilibrium. (on the line in Table G)

9 A solution that contains less solute than a saturated solution under existing conditions is unsaturated. (below the line on Table G) Unsaturated

10 Supersaturated

11 Solids vs- Gases Solids are more soluble at... high temperatures. Gases are more soluble at... low temperatures & high pressures

13 A simple way to convert between units is using the Molarity TRIANGLE. Mole M(mol/L) X Liter

14 Dilutions Acids are usually acquired in concentrated form and then diluted to the desired concentration, by adding water (aqueous solution). Since moles of acid before dilution = moles of acid after dilution, and moles of acid = M (molarity) x V (volume), then M 1 V 1 = M 2 V 2

15 Dilution Example How much concentrated 18 M sulfuric acid is needed to prepare 250 ml of a 6.0 M solution? Step 1: Substitute into dilution formula and solve: M 1 V 1 = M 2 V 2 18 M x V 1 = 6.0 M x 250 ml V 1 = 83 ml

16 Like Dissolves Like depends on the forces of attraction Solute type nonpolar solvent polar solvent Nonpolar soluble insoluble Polar insoluble soluble Ionic insoluble soluble

17 ppm grams of water is evaporated and analyzed for lead grams of lead ions are found. What is the concentration of the lead, in parts per million? ppm = grams of solute x 1,000,000 grams of solution = ( g) x 1,000, g = 1.0 ppm (10 6 ) *On Table T If the legal limit for lead in the water is 3.0 ppm, then the water sample is within the legal limits (it s safe and ok)

18 Concentration by % Mass = Mass of solute (g) (PART) X 100 Mass of Solvent or Solution (g) (WHOLE) A 50.0 gram sample of a solution is evaporated and found to contain grams of sodium chloride. What is the percent by mass of sodium chloride in the solution? % mass = g X g = 0.200%

19 Concentration % Volume = Volume of solute (ml) X 100 Volume of Solvent or Solution (ml) Substitute volume of part divide by volume of whole) in the above equation and multiply by 100 Ex.#1 What is the percent by volume of hexane if 20.0 ml of hexane are dissolved in benzene to a total volume of 80.0 ml? % volume = volume of solute x 100 volume of solution = 20.0 ml x ml = 25.0%

20 Solvation - the process of dissolving solute particles are surrounded by solvent particles solute particles are separated and pulled into solution

21 Dissociation separation of an ionic solid into aqueous ions NaCl(s) Na + (aq) + Cl (aq)

22 Molecular Solvation -molecules stay intact C 6 H 12 O 6 (s) C 6 H 12 O 6 (aq)

23 Solvation and Conductivity sugar Non- Electrolyte solute exists as molecules only acetic acid Weak Electrolyte solute exists as ions and molecules salt Strong Electrolyte solute exists as ions only DISSOCIATION

24 Colligative Properties depend on the number of particles rather than the nature of the particles in the solution. Boiling point and freezing point some of the properties affected.

25 Freezing Point Depression f.p. of a solution is lower than f.p. of the pure solvent

26 Boiling Point Elevation b.p. of a solution is higher than b.p. of the pure solvent Solute particles weaken intermolecular forces in the solvent.

27 Applications salting icy roads making ice cream Antifreeze (ethylene glycol) cars (-64 C to 136 C) fish & insects (have a natural antifreeze)

28 Colligative Properties con t. # of Particles Nonelectrolytes (covalent: non-metals) remain intact when dissolved 1 particle Electrolytes (ionic-metal +non-metal) dissociate into ions when dissolved 2 or more particles

29 Boiling point elevation It is proportional to the concentration of dissolved particles 1 mole of particles in solution raises the BP of water by 0.52 C Which solution will have the highest boiling point? KNO 3 Mg(NO 3 ) 2 Al(NO 3 ) 3

30 Freezing Point Depression It is proportional to the concentration of dissolved particles 1 mole of particles in solution depresses the FP of water by 1.86 C What solution will depress the FP of water the most. AlCl 3 or MgCl 2? Why?

Chapter 13. Characteristics of a Solution. Example of A Homogenous Mixtures. Solutions

Chapter 13. Characteristics of a Solution. Example of A Homogenous Mixtures. Solutions Chapter 13 Solutions Characteristics of a Solution A solution is a homogeneous mixture A solution is composed of a: Solute: the substance in lesser amount Solvent: the substance in greater amount Two liquid