Chapter 8 Solutions

Chapter 8Solutions Solubility Percent Concentration Colloids and Suspensions

Solute and Solvent Solutions are homogeneous mixtures of two or more substances • Solute The substance in the lesser amount • Solvent The substance in the greater amount

Formation of solutions

Nature of Solutes in Solutions • Spread evenly throughout the solution • Cannot be separated by filtration • Can be separated by evaporation • Not visible, solution appears transparent • May give a color to the solution

Types of Solutions air O2 gas and N2 gas gas/gas soda CO2 gas in water gas/liquid seawater NaCl in water solid/liquid brass copper and zinc solid/solid

H2O Hydration Na+ Cl- Na+ Cl- Dissolved solute H2O Na+ Cl- solute Formation of solutions - solvation

Formation of solutions - creating like-like interactions Water Most common solvent A polar molecule O- a hydrogen bond H + H +

Formation of solutions - creating like-like interactions

When NaCl(s) dissolves in water, the reaction can be written as H2O NaCl(s) Na+ (aq) + Cl- (aq) solid separation of ions in water Formation of solutions - creating like-like interactions

Formation of solutions - creating like-like interactions Solid LiCl is added to some water. It dissolves because A. The Li+ ions are attracted to the 1) oxygen atom(-) of water 2) hydrogen atom(+) of water B. The Cl- ions are attracted to the 1) oxygen atom(-) of water 2) hydrogen atom(+) of water Solid LiCl is added to some water. It dissolves because A. The Li+ ions are attracted to the 1) oxygen atom(-) of water B. The Cl- ions are attracted to the 2) hydrogen atom(+) of water

Solubility The maximum amount of solute that can dissolve in a specific amount of solvent usually 100 g. g of solute 100 g water

Saturated and Unsaturated • A saturated solution contains the maximum amount of solute that can dissolve. Undissolved solute remains. • An unsaturated solution does not contain all the solute that could dissolve

Learning Check At 40C, the solubility of KBr is 80 g/100 g H2O. Indicate if the following solutions are (1) saturated or (2) unsaturated A. ___60 g KBr in 100 g of water at 40C B. ___200 g KBr in 200 g of water at 40C C. ___25g KBr in 50 g of water at 40C

Solution At 40C, the solubility of KBr is 80 g/100 g H2O. Indicate if the following solutions are (1) saturated or (2) unsaturated A. 2 Less than 80 g/100 g H2O B. 1 Same as 100 g KBr in 100 g of water at 40C, which is greater than its solubility C. 2 Same as 60 g KBr in 100 g of water, which is less than its solubility

Temperature and Solubility of Solids Temperature Solubility (g/100 g H2O) KCl(s) NaNO3(s) 0°27.6 74 20°C34.0 88 50°C42.6 114 100°C57.6 182 The solubility of most solids (decreases or increases ) with an increase in the temperature.

Temperature and Solubility of Solids Temperature Solubility (g/100 g H2O) KCl(s) NaNO3(s) 0°27.6 74 20°C34.0 88 50°C42.6 114 100°C57.6 182 The solubility of most solids increases with an increase in the temperature.

Temperature and Solubility of Gases Temperature Solubility (g/100 g H2O) CO2(g) O2(g) 0°C 0.34 0.0070 20°C0.17 0.0043 50°C0.076 0.0026 The solubility of gases (decreases or increases) with an increase in temperature.

Temperature and Solubility of Gases Temperature Solubility (g/100 g H2O) CO2(g) O2(g) 0°C0.34 0.0070 20°C0.17 0.0043 50°C0.076 0.0026 The solubility of gases decreases with an increase in temperature.

Learning Check A. Why would a bottle of carbonated drink possibly burst (explode) when it is left out in the hot sun ? B.Why would fish die in water that gets too warm?

Solution A. Gas in the bottle builds up as the gas becomes less soluble in water at high temperatures, which may cause the bottle to explode. B. Because O2 gas is less soluble in warm water, the fish may not obtain the needed amount of O2 for their survival.

Soluble and Insoluble Salts A soluble salt is an ionic compound that dissolves in water. An insoluble salt is an ionic compound that does not dissolve in water

Solubility Rules 1. A salt is solublein water if it contains any one of the following ions: NH4+ Li+ Na+ K+ or NO3- Examples: soluble salts LiCl Na2SO4 KBr Ca(NO3)2

Cl- Salts 2. Salts with Cl- are soluble, but not if the positive ion is Ag+, Pb2+, or Hg22+. Examples: soluble not soluble(will not dissolve) MgCl2 AgCl PbCl2

SO42- Salts 3. Salts with SO42- are soluble, but not if the positive ion is Ba2+,Pb2+, Hg2+ or Ca2+. Examples: soluble not soluble MgSO4 BaSO4 PbSO4

Other Salts 4. Most salts containing CO32-, PO43-, S2- and OH- are not soluble. Examples: soluble not soluble Na2CO3 CaCO3 K2S CuS

Learning Check Indicate if each salt is (1)soluble or (2)not soluble: A. ______ Na2SO4 B. ______ MgCO3 C. ______ PbCl2 D. ______ MgCl2

Solution Indicate if each salt is (1) soluble or (2) not soluble: A._1_ Na2SO4 B. _2_ MgCO3 C. _2_ PbCl2 D. _1_ MgCl2

Molarity (M) A concentration that expresses the moles of solute in 1 L of solution Molarity (M) = moles of solute 1 liter solution

Units of Molarity 2.0 M HCl = 2.0 moles HCl 1 L HCl solution 6.0 M HCl = 6.0 moles HCl 1 L HCl solution

Molarity Calculation NaOH is used to open stopped sinks, to treat cellulose in the making of nylon, and to remove potato peels commercially. If 4.0 g NaOH are used to make 500. mL of NaOH solution, what is the molarity (M) of the solution?

Calculating Molarity 1) 4.0 g NaOH x 1 mole NaOH = 0.10 mole NaOH 40.0 g NaOH 2) 500. mL x 1 L _ = 0.500 L 1000 mL 3. 0.10 mole NaOH = 0.20 mole NaOH 0.500 L 1 L = 0.20 M NaOH

Learning Check A KOH solution with a volume of 400 mL contains 2 mole KOH. What is the molarity of the solution? 1) 8 M 2) 5 M 3) 2 M Drano

Solutions A KOH solution with a volume of 400 mL contains 2 moles of KOH. What is the molarity of the solution? 2) 5 M M = 2 mole KOH = 5 M 0.4 L Drano

Learning Check A glucose solution with a volume of 2.0 L contains 72 g glucose (C6H12O6). If glucose has a molar mass of 180. g/mole, what is the molarity of the glucose solution? 1) 0.20 M 2) 5.0 M 3) 36 M

Solution A glucose solution with a volume of 2.0 L contains 72 g glucose (C6H12O6). If glucose has a molar mass of 180. g/mole, what is the molarity of the glucose solution? 1) 72 g x 1 mole x 1 = 0.20 M 180. g 2.0 L

Molarity Conversion Factors A solution is a 3.0 M NaOH.. Write the molarity in the form of conversion factors. 3.0 moles NaOHand 1 L NaOH soln 1 L NaOH soln 3.0 moles NaOH

Learning Check Stomach acid is a 0.10 M HCl solution. How many moles of HCl are in 1500 mL of stomach acid solution? 1) 15 moles HCl 2) 1.5 moles HCl 3) 0.15 moles HCl

Solution 3) 1500 mL x 1 L = 1.5 L 1000 mL 1.5 L x 0.10 mole HCl = 0.15 mole HCl 1 L (Molarity factor)

Learning Check How many grams of KCl are present in 2.5 L of 0.50 M KCl? 1) 1.3 g 2) 5.0 g 3) 93 g

Solution M4 3) 2.5 L x 0.50 mole x 74.6 g KCl = 93 g KCl 1 L 1 mole KCl

Learning Check How many milliliters of stomach acid, which is 0.10 M HCl, contain 0.15 mole HCl? 1) 150 mL 2) 1500 mL 3) 5000 mL

Solution 2)0.15 mole HCl x 1 L soln x 1000 mL 0.10 mole HCl 1 L (Molarity inverted) = 1500 mL HCl

Learning Check How many grams of NaOH are required to prepare 400. mL of 3.0 M NaOH solution? 1) 12 g 2) 48 g 3) 300 g

Solution 2) 400. mL x 1 L = 0.400 L 1000 mL 0.400 L x 3.0 mole NaOH x 40.0 g NaOH 1 L 1 mole NaOH (molar mass) = 48 g NaOH

Learning Check

Chapter 8 Solutions