Presentation on theme: "IN THE NAME OF ALLAH THE MOST GRACIOUS, THE MOST MERCIFUL"— Presentation transcript:
1 IN THE NAME OF ALLAH THE MOST GRACIOUS, THE MOST MERCIFUL CHEM 122. LEVEL-2 LECTURE # 1 CHAPTER 8 - SOLUTIONSChemistry by Timberlake p.226Presented by:Department OfChemistryRCDP
2 Types of mixtures 2- Colloidal solution/dispersion 3-Suspension
3 1- True solution:It is a homogeneous mixture of two or more substances.One substance which is called the solute is uniformly dispersed in another substance called the solvent.Every part of the solution possesses the same composition, density, viscosity.Example: Sugar in water
4 Solvent:The component present in larger amount in solution.Solute:The component present in smaller amount in solution (in lesser amount).Solubility:Maximum amount of solute dissolved in a fixed quantity of solvent ( 100g) at a given temperature to form a saturated solution.
5 TYPES of SOLUTIONS: Three States of matter : SOLIDGASLIQUID
6 Types of solutions (7):A solution of gas in gas, example air (O2 gas in N2 gas)A solution of gas in liquid, example aerated water such as soda water (CO2 in water)A solution of gas in solid , example hydrogen in palladium (Pd)A solution of liquid in liquid, example Benzene in toluene.A solution of liquid in solid, example Amalgamated zinc (mercury in zinc)A solution of solid in liquid, example seawater (NaCl in water).A solution of solid in solid, Alloys, example Cu in Au (gold) and brass (zinc in copper).Au is gold
7 gas/gas air O2 gas and N2 gas gas/liquid soda CO2 gas in water Type of solution Example Components of solutiongas/gas air O2 gas and N2 gasgas/liquid soda CO2 gas in watersolid/liquid seawater NaCl in watersolid/solid brass zinc and copper
8 Properties of solution : It is a homogeneous mixture of two or more substances, where the solute,1-May spread evenly throughout the solution.2-Cannot be separated by filtration.3-Can be separated by evaporation.4-Is not visible, solution appears transparent5-May give a color to the solution.
9 Q1: Identify the element (1), compound (2) or solution (3) : watersugarsalt waterairtea
10 Q2- Identify the solute in each of the following solutions: a) 2 g sugar mL waterb) 60.0 mL ethyl alcohol mLof methyl alcoholc) 55.0 mL water g NaCld) Air: 200 mL O mL N2e) brass: 20 g zinc + 50 g copperf) 100 g H2O g KCl
11 Factors influencing solubility: 1-Temperature:(A) If the formation of solution is endothermic then the solubility increases with the increase in temperature.heat + solute + solution (1) ⇌ solution (2)(B) If the formation of solution is exothermic then solubility decreases with the increase in temperature.gas + solution (1) ⇌ solution (2) + heatExample :Solubility of gases are exothermic. Gases are less soluble at higher temperatures
12 2-Pressure :Solubility of gases increases with increasing pressure.Henry’s Law: The solubility of a gas in a liquid solution is directly proportional to the pressure of the gas above the solution.
13 3-Common ion effect:Solubility of AgCl decreases in the solution of NaCl compared to the solubility of AgCl in pure water.This is because of the chloride ion which is a common ion.
14 Types of solutions according to solute concentration: Saturated solution:Solution contains maximum amount of solute at a given temperature and pressureUnsaturated solution:Solution contains less than the maximum quantity of solute, or if the solution is not saturated.Dilute solution:Quantity of solute is very less in solution.
15 Types of mixtures(cont.) 2- Colloidal solutions/ dispersions:-These are heterogeneous (non-uniform mixtures.)-In colloidal dispersion, the size of the solute molecules are intermediate between the size of solute molecules in true solution and those in suspension.Range of size 1 to 1000nmExample, Milk, Butter in H2O
16 Properties of Colloids Have medium size particles, that do not settle out (separate).Particles cannot be filtered (particles are small enough to be pass through filters).Can be separated with semi permeable membranes (particles are too large to pass through semi permeable membranes).Scatter light (Tyndall effect)
17 Examples of Colloids Fog, clouds (liquid in gas) Whipped cream (gas in liquid)Homogenized Milk (liquid in liquid)Cheese (liquid in solid)Blood plasma (solid in liquid)Pearls (solid in solid)
18 3- SUSPENSIONS: These are heterogeneous non-uniform mixtures. Properties of SuspensionsHave very large particles (can be seen by eye)Settle outCan be filteredMust be stirred to stay suspendedN.B:It is important to “Shake well before using” before giving a suspension medication.
19 Examples of Suspensions Blood plateletsMuddy waterCalamine lotion
20 Comparison:(Homogeneous) (Heterogeneous)Solution Colloid Suspension- small particles intermediate particles large particles< 1 nm bet nm >1000 nm- does not separate does not separate separates on standingover time over time- cannot be filtered cannot be filtered can be filtered(can be separated withsemi permeable membranes)- no Tyndall Effect Tyndall Effect present Tyndall Effect present- e.g.: salt/H e.g.: milk, gel, smoke, e.g.: clay/water ,foam Italian salad dressing
21 This is due to the polar and non polar nature of solvent. Polar and non polar solvents:Some substances are soluble in one solvent but not in another solvent.This is due to the polar and non polar nature of solvent.Example: Sugar is soluble in water but not in petrol.Alcohol and water are completely miscible in each other, this is due to the hydrogen bonding.Two non polar substances are miscible(Hexane in Carbon tetrachloride).
22 Miscible: Fluids that completely dissolve in each other. Non-polar C6H14 will not dissolve in polar H2O.Non-polar C6H14 will dissolve in non-polar CCl4.
23 “ Like dissolves like ”General rule for solutions is “like dissolves like.” Polar dissolves polar & non-polar dissolves non-polar.Examples:I2 is soluble in CCl4 & relatively insoluble in waterNaCl is soluble in water but not in non polar solvents.Polar molecule like CH3OH will dissolve as a molecule in polar H2O.Ionic LiF will dissolve as ions in polar H2O.
24 Polar solutes dissolve in polar solvents. Solvation and hydration:Polar solutes dissolve in polar solvents.Ionic substances furnish cations (+) and anions ( - ).These ions are surrounded by solvent molecules this is known as solvation and if the solvent is water then it is called hydration. Example NaCl in water.
26 NaCl(s) H2O Na+ (aq)+Cl(aq) When NaCl(s) dissolves in water, the reaction can be written asNaCl(s) H2O Na+ (aq)+Cl(aq)solid separation of ions in water
27 Q1: Solid LiCl is added to some water. It dissolves because A. The Li+ ions are attracted to the1) oxygen atom(-) of water2) hydrogen atom(+) of waterB. The Cl- ions are attracted to the
28 Solid LiCl is added to some water. It dissolves because Answer:Solid LiCl is added to some water. It dissolves becauseA. The Li+ ions are attracted to the1) oxygen atom(-) of waterB. The Cl- ions are attracted to the2) hydrogen atom(+) of water
29 Q2: Like dissolves likeA ____________ solvent such as water is needed to dissolve polar solutes such as sugar and ionic solutes such as NaCl.A ___________solvent such as hexane (C6H14) is needed to dissolve nonpolar solutes such as oil or grease.
30 Q3:Which of the following solutes will dissolve in water? Why? 1) Na2SO42) gasoline3) I24) HCl
31 Answer:1) Na2SO Yes, polar (ionic)2) gasoline No, nonnpolar3) I2 No, nonpolar4) HCl Yes, Polar
32 Spectator ion:Two ionic compounds NaCl and AgNO3 in water exist as Na+, Cl- and Ag+, (NO3) - ,ions and react with each otherAg+aq + NO3 aq + Na+aq + Cl-aq → AgCl s↓ + Na+aq+ NO3 aqThis equation is called ionic equation.In this reaction Na+ and NO3 ions do not change during a reaction are called spectator ions.They are the same before and after the reaction.
33 Ag+aq + Cl-aq → AgCl↓ ( net ionic equation ) Ag+aq + NO3 aq + Na+aq + Cl-aq → AgCl s↓ + Na+aq+ NO3 aqwhile writing an ionic equation we can omit the spectator ions.This equation is known as net ionic equationAg+aq + NO3 aq + Na+aq + Cl-aq → AgCl s↓ + Na+aq+ NO3 aqAg+aq + Cl-aq → AgCl↓ ( net ionic equation )
34 Another example: AgF aq + KCl aq → AgCl s +KF aq – molecular equation Ag+aq + F-aq + K+aq + Cl-aq → AgCl ↓ + K+ + F- ---ionic equationAg+aq Cl-aq → AgCl ↓ ---net ionic equation
35 PCDPR-CHEM.122 LEVEL 2 MCQz Q1. Indicate solution among the following: A). Water b) salt-water c) air d) both b & cQ2. Brass is an alloy of 20 g zinc + 50g copper. Identify the solute:A). 20 g zinc b) 50g copperc) both a & b d) none of the aboveQ3. Identify solvent in 55ml water & 2g NaClA). 55ml water b) 2g NaCl
36 Q4.Solubility of gases increases with rise in: A). Pressure b) temperaturec) both a &b d) none of the aboveQ5. The process in which water is taken as solvent is called:A). solvation b) hydrationc) evaporation d) condensation
37 Q6. Iodine I2 is soluble in CCl4: A) True b) FalseQ7.Polar or ionic solutes are dissolved in:A). Polar solvents b) non Polar solventsc) Polar solutes d) non Polar solutesQ8. Which solute will dissolve in water?A) Na2SO4 b) gasoline c) I2 d) Hexane