Solution Chemistry (Chp. 7) Chemistry 2202

Topics Molar Concentration (mol/L) Dilutions % Concentration (pp. 255 – 263) Solution Process Solution Preparation Solution Stoichiometry Dissociation

Terms solution solvent solute concentrated dilute aqueous miscible Immiscible alloy solubility x molar solubility saturated unsaturated supersaturated dissociation electrolyte non-electrolyte filtrate precipitate limiting reagent excess reagent actual yield theoretical yield decanting pipetting dynamic equilibrium

 Define the terms in bold and italics from pp. 237 – 240.  Solids, liquids, and gases can combine to produce 9 different types of solution. Give an example of each type.  p. 242 #’s 5, 7, 9, & 10

Terms solution solvent solute concentrated dilute aqueous miscible immiscible x alloy solubility molar solubility saturated unsaturated supersaturated dynamic equilibrium

Factors Affecting Solubility (pp.243 – 254) 1. List 3 factors that affect the rate of dissolving. 2. How does each of the following affect solubility?  particle size  temperature  pressure

Factors Affecting Solubility 3. What type of solvent will dissolve:  polar solutes  nonpolar solutes  ionic solutes 4. Why do some ionic compounds have low solubility in water? p. 254 #’s 1, 2, 4 - 6

Section 7.2 (pp. 243 – 252) State the generalizations regarding solubility and solutions (in italics) Define terms (in bold)

rate of dissolvingdipole ion-dipole attractions hydrated electrolyte. non-electrolytes

Rate of Dissolving for most solids, the rate of dissolving is greater at higher temperatures stirring a mixture or by shaking the container increases the rate of dissolving. decreasing the size of the particles increases the rate of dissolving.

“Like Dissolves Like” ionic solutes and polar covalent solutes both dissolve in polar solvents non-polar solutes dissolve in non- polar solvents.

Solubility small molecules are often more soluble than larger molecules. the solubility of most solids increases with temperature. the solubility of most liquids is not greatly affected by temperature. the solubility of gases decreases as temperature increases

Solubility An increase in pressure increases the solubility of a gas in a liquid.

Applications 1. An opened soft drink goes ‘flat’ faster if not refrigerated. 2. Warming of pond water may not be healthy for the fish living in it. 3. After pouring 5 glasses of pop from a 2 litre container, Jonny stoppered the bottle and crushed it to prevent the remaining pop from going flat.

Molar Concentration Review: - Find the molar mass of Ca(OH) 2 - How many moles in g of Ca(OH) 2 ? - Find the mass of mol of Ca(OH) 2.

Molar Concentration The terms concentrated and dilute are qualitative descriptions of solubility. A quantitative measure of solubility uses numbers to describe the concentration of a solution.

Molar Concentration The MOLAR CONCENTRATION of a solution is the number of moles of solute (n) per litre of solution (v).

Molar Concentration FORMULA: Molar Concentration = number of moles volume in litres C = n V

eg. Calculate the molar concentration of: 4.65 mol of NaOH is dissolved to prepare 2.83 L of solution g of NaOH is dissolved to prepare 475 mL of solution. p # 19

Eg. Calculate the following: a) the number of moles in 4.68 L of mol/L KCl solution. b) the mass of KCl in 268 mL of 2.50 mol/L KCl solution.

c) the volume of 6.00 mol/L HCl (aq) that can be made using mol of HCl. d) the volume of 1.60 mol/L HCl (aq) that can be made using 20.0 g of HCl. p. 268 #’s20-24

Dilution (p. 272) When a solution is diluted: - The concentration decreases - The volume increases - The number of moles remains the same n i = n f Number of moles after dilution Number of moles before dilution

Dilution (p. 272) n i = n f C i V i = C f V f eg. Calculate the molar concentration of a vinegar solution prepared by diluting 10.0 mL of a 17.4 mol/L solution to a final volume of 3.50 L.

p. 273 #’s 25 – 27 p. 276 #’s 1, 2, 4, & 5 DON’T SHOW UP UNLESS THIS IS DONE!!

Solution Preparation & Dilution standard solution – a solution of known concentration volumetric flask – a flat-bottomed glass vessel that is used to prepare a standard solution delivery pipet – pipets that accurately measure one volume graduated pipet – pipets that have a series of lines that can be use to measure many different volumes

To prepare a standard solution: 1. calculate the mass of solute needed 2. weigh out the desired mass 3. dissolve the solute in a beaker using less than the desired volume 4. transfer the solution to a volumetric flask (rinse the beaker into the flask) 5. add water until the bottom of the meniscus is at the etched line

To dilute a standard solution: 1. Rinse the pipet several times with deionized water. 2.Rinse the pipet twice with the standard solution. 3.Use the pipet to transfer the required volume. 4. Add enough water to bring the solution to its final volume.

Percent Concentration Concentration may also be given as a %. The amount of solute is a percentage of the total volume/mass of solution.  liquids in liquids - % v/v  solids in liquids - % m/v  solids in solids - % m/m

Percent Concentration p. 258 #’s 1 – 3 DSUUTID!!

p. 261 #’s 5 – 9 DSUUTID!!

p. 263 #’s 10 – 13 DSUUTID!!

Concentration in ppm and ppb Parts per million (ppm) and parts per billion (ppb) are used for extremely small concentrations

eg mg of NaF is dissolved in kg of solution. Calculate the concentration in: a) ppm b) ppb

ppm = g x ,000 g = 0.05 ppm ppb = g x ,000 g = 50.0 ppb

p. 265 #’s 15 – 17 pp. 277, 278 #’s 11, 13, 15 – 18, 20 DON’T SHOW UP UNLESS THIS IS DONE!!

Solution Stoichiometry 1.Write a balanced equation 2.Calculate moles given n=m/M OR n=CV 3.Mole ratios 4.Calculate required quantity

Solution Stoichiometry eg mL of a HCl (aq) solution is used to neutralize 30.0 mL of a 2.48 mol/L NaOH solution. Calculate the molar concentration of the HCl (aq) solution. p. 304: #’s 16, 17, & 18 Worksheet

Sample Problems 1.What mass of copper metal is needed to react with mL of mol/L silver nitrate solution? 2.Calculate the volume of 2.00 M HCl (aq) needed to neutralize 1.20 g of dissolved NaOH. 3.What volume of 3.00 mol/L HNO 3(aq) is needed to neutralize mL of mol/L Sr(OH) 2(aq) ?

Sample Problem Solutions Cu (s) + 2 AgNO 3(aq) → 2 Ag (s) + Cu(NO 3 ) 2(aq) Step 2n = mol AgNO 3 Step 3n = mol Cu Step 4m = g Cu

Sample Problem Solutions HCl (aq) + NaOH (aq) → NaCl (aq) + H 2 O (l) Step 2n = mol NaOH Step 3n = mol HCl Step 4V = L HCl

Sample Problem Solutions 2 HNO 3(aq) + Sr(OH) 2(aq) → 2 H 2 O (l) + Sr(NO 3 ) 2(aq) Step 2n = mol Sr(OH) 2 Step 3n = mol HNO 3 Step 4V = mol/L HNO 3

The Solution Process (p. 299) Dissociation occurs when an ionic compound breaks into ions as it dissolves in water. Dissociation A dissociation equation shows what happens to an ionic compound in water. eg. NaCl (s) → Na + (aq) + Cl - (aq) K 2 SO 4(s) → 2 K + (aq) + SO 4 2- (aq)

The Solution Process (p. 299) Solutions of ionic compounds conduct electric current. A solute that conducts an electric current in an aqueous solution is called an electrolyte.

The Solution Process (p. 299) Acids are also electrolytes. Acids form ions when dissolved in water. eg.H 2 SO 4(aq) → 2 H + (aq) + SO 4 2- (aq) HCl (s) → H + (aq) + Cl - (aq)

Molecular Compounds DO NOT dissociate in water. eg. C 12 H 22 O 11(s) → C 12 H 22 O 11(aq) Because they DO NOT conduct electric current in solution, molecular compounds are non-electrolytes. The Solution Process (p. 299)

The molar concentration of any dissolved ion is calculated using the ratio from the dissociation equation. eq. What is the molar concentration of each ion in a 5.00 mol/L MgCl 2(aq) solution: 5.00 mol/L mol/L The Solution Process (p. 299)

p. 300 #’s 7 – 9 p. 300 #’s 7 – 9 What mass of calcium chloride is required to prepare 2.00 L of mol/L Cl - (aq) solution? p. 302 # 14 p. 302 # 14 p. 311 #’s 11, 12, 16, & 18 p. 311 #’s 11, 12, 16, & 18