Warm UP. between carbonate and lithium. following elements have? 3) Name these compounds: 1) Write the neutral compound that forms

Transcription

1 Warm UP 1) Write the neutral compound that forms between carbonate and lithium 2) How many valence electrons do the following elements have? a) Chlorine b) Neon c) Potassium 3) Name these compounds: a) CoCl 2 b) NH 3 c) Sr 3 N 2

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3 Solutions Solute- the substance being put into the solution. Solvent- the substance in which the solute is being put into. Solution- the substance that results from a solute being put into a solvent. Example: Salt is a solute, Water is the solvent, Salt Water is the solution.

4 Types of Solutions Solute Solvent Example Solution Gas Gas Air Gas Liquid Soda Liquid Liquid Juice Solid Liquid Sweet Tea Solid Solid Steel

5 Solutions Soluble versus Insoluble. Soluble dissolved in solution. Insoluble will not dissolve in solution. Miscible versus Immiscible. Miscible Mixable able to mix together. (Ex. Water and Bleach) Immiscible Not able to mix together. (Ex. Water and Oil)

6 Types of Mixtures Solution Colloid Suspension Particle Size <1 nm nm > 1000 nm Tyndall Effect (scattering of light) No Yes Yes Settles out/filtration No No Yes Mixture Type Homogeneous Heterogeneous Heterogeneous Example Salt water Fog/Milk Muddy water

7 Solutions as Electrolytes Electrolyte: substances that dissolve in water to give a solution that conducts electricity Good electrolytes: substances that form IONS ionic compounds, acids, bases Non-electrolytes: aqueous solutions that do not conduct electricity most molecular compounds (organic substances), alcohols, sugars (NO IONS!)

8 Electrolyte or Nonelectrolyte? NaCl

9 Electrolyte or Nonelectrolyte? H 2 SO 4

10 Electrolyte or Nonelectrolyte? CO 2

11 Electrolyte or Nonelectrolyte? Ca(OH) 2

12 Electrolyte or Nonelectrolyte? C 6 H 12 O 6

13 Electrolyte or Nonelectrolyte? NH 3

14 Electrolyte or Nonelectrolyte? K 3 PO 4

15 Electrolyte or Nonelectrolyte? CCl 4

16 Electrolyte or Nonelectrolyte? Ca(OH) 2

17 Electrolyte or Nonelectrolyte? HCl

18 Electrolyte or Nonelectrolyte? SO 2

19 Electrolyte or Nonelectrolyte? KOH

20 Warm-up What are the main differences between solutions, colloids, and suspensions. Look back at your notes before answering! What is an electrolyte? Which of the following are electrolytes? Ca 3 N 2, Mg(OH) 2, CF 4, HClO 3, C 12 H 22 O 11

21 Water The Universal Solvent most abundant liquid on earth, is essential for all life because most biological chemical reactions are aqueous reactions

22 Water continued What are some properties of water that make it a good solvent? Polar molecule forms H-bonds Intermolecular forces, water remains a liquid for a large temperature span (high molar heat of vaporization, high specific heat, high boiling point) Polarity allows water to surround ions and polar compounds to keep them separate

23 likes dissolves likes determines solubility based on bonding, polarity, and intermolecular forces between solute and solvent Polar/ionic solute and Polar solvent: attraction exists, solution may form if solute-solvent forces greater than solute-solute or solvent-solvent Nonpolar solute and Nonpolar solvent: very weak attractions between solutes, solvents or solutesolvent, random mixing occurs Polar/Nonpolar combinations: forces of attraction only between polar component, no dissolving occurs

24 Electrolyte Versus Nonelectrolyte Electrolyte- Ionic compounds that dissociate (or break apart) into their charged ions. Conducts electricity Nonelectrolyte- usually Covalent compounds DOES NOT conduct electricity. (No ions)

25 The Solution Process most solutions form due to forces of attraction between solute and solvent particles Solvation: process by which solvent particles surround solute particles Dissociation: separation of ionic compounds into ions Hydration: solvation with water (ions are surrounded and kept separate)

26 Dissociation The separation of ions from one another.

27 Hydration Water molecules attach to dissolving molecules and ions.

28 Warm-up What happens to the solubility of gases as you increase temperature? How many grams of HCl can dissolve in 100 grams of water at 20 C? 100 grams of water is holding 60 grams of NH 4 Cl at 40 C. Is it saturated, unsaturated, or supersaturated? How many grams of KNO 3 can 200 grams of water hold at 60 C

29 Factors that Affect Rate of Solution Increasing surface area: if dissolving takes place on the surface of a crystalline solid, increasing surface area provides more surfaces therefore increasing the rate of solution, can increase surface area by crushing and stirring Increasing temperature: increases kinetic energy of your particles more solute/solvent collisions therefore increasing your rate of solution

30 More Factors that Affect Rate of Solution Nature of solute and solvent: bonding, polarity, intermolecular forces affect the degree of forces of attraction between solute and solvent Increasing pressure: This is true for gases only, increasing pressure increases the amount of gas/solvent collisions and increases the rate (Think about soda) Increasing concentration more particles means more collisions, so rate increases Using a catalyst speeds up the rate by lowering activation energy

31 Solubility There is a direct relationship between the amount of solute that dissolves and the temperature for solids and liquids. Gases decrease solubility with increased temperature Pressure only impacts the solubility of gases -> increase pressure increases their solubility Likes dissolve Likes more similar the polarities, the more imfs are created, the more soluble the solute is in the solvent

32 Solubility Curves Shows the amount of a solute (in grams) that will dissolve in a specific amount of water (usually 100g) at various temperatures.

33 Key Terms: Saturated solution is holding the maximum amount of solute that it can hold Unsaturated solution is holding less than the maximum amount of solute Supersaturated solution is holding more than the maximum amount of solute

34 Try It: 1. Which substance has the highest solubility at 80 C? 2. How much KCl can 100 g of water hold at 50 C? 3. If a solution contains 100 g of NaNO 3 at 20 C, is the solution saturated, unsaturated, or supersaturated?

35 Solution Concentration Concentration is a measure of the amount of solute in the amount of solvent or solution. Qualitative measures of concentration Dilute: small amount of solute compared to the amount of solvent (could be a saturated solution) Concentrated: large amount of solute compared to the amount of solvent

36 Molarity and Concentration Quantitative measures of concentration: Molarity ( M ) moles solute liters solution

37 Practice Problem 1 What is the molarity of a solution containing 5.85 grams of potassium iodide in 125 ml of solution?

38 Practice Problem 2 How many moles of sulfuric acid are present in 500 ml of a M solution?

39 Practice Problem 3 What volume of a 3.00 M solution of sodium chloride contains grams of solute?

40 Diluting Solutions 12M H 2 O 2M Mole 1 = Mole 2 M=mol/volume ; mol= (M)(V) (M 1 )(V 1 )=(M 2 )(V 2 )

41 Diluting Solutions Practice Problem What volume of 2.00M CaCl 2 would you use to make 0.5L of 0.300M CaCl 2?

42 Colligative Properties Physical properties of a solution that are affected by the number of solute particles. Vapor pressure lowers Boiling point rises Freezing point lowers Osmotic pressure increases

43 Colligative Properites Electrolytes: NaCl(s) Na + (aq) + Cl - (aq) 1m 1m + 1m = 2m of particles 1m CaCl 2 = 3m of particles. Nonelectrolytes: C 12 H 22 O 11 (s) C 12 H 22 O 11 (aq) 1m nonelectrolyte 1m nonelectrolyte

44 Vapor Pressure Lowering The lowering of vapor pressure of a solvent by the addition of a non volatile solute to the solvent The greater the number solute particles in a solvent, the lower the resulting vapor pressure.

45 Boiling Point Elevation The difference between a solution s boiling point and a pure substance s boiling point Think about it: Adding salt to boiling water Increases boiling point because more imfs between solute and solvent to break before the solution boils

46 Freezing Point Depression The difference in temperature between a solution s freezing point and the freezing point of its pure solvent Decreases freezing point because more imfs to overcome before the solution freezes

47 Osmotic Pressure The pressure needed to reverse or stop osmosis Osmosis: the diffusion of solvent particles across a semipermeable membrane