Chemistry 1Name:______

West Linn High School

Unit 9 Packet and GoalsPeriod:______

Unit 9 – Water, Solutions and Acids/Bases

Unit Goals:

As you work through this unit, you should be able to:

  1. Describe hydrogen bonding in water and how it explains water’s properties. (15.1)
  2. Describe a solution and its components. (15.2)
  3. Explain why some substances dissolve in others. (15.2)
  4. Distinguish among strong electrolyte, weak electrolyte, and nonelectrolyte solutions. (15.2)
  5. Identify factors that determine the rate a solute dissolves. (16.1)
  6. Solve concentration problems involving molarity, dilution, and percent. (16.2)
  7. understand how to distinguish between Arrhenius and Bronsted-Lowry acid and bases (19.1)
  8. understand how some compounds can function as both a Bronsted acid and a Bronsted base (19.1)
  9. understand how to identify conjugate acid-base pairs in a reaction (19.1)
  10. be able to calculate: concentrations of H3O+, concentrations of OH-, and pH of a solution (19.2)
  11. write an equation for a neutralization reaction (19.4)

Readings:

  • Chapter 15 (pp 486-497) Sections 15.1 – 15.2
  • Chapter 16 (pp 516-531) Sections 16.1 – 16.2
  • Chapter 19: (pp 644-684) Sections 19.1 – 19.2

Key Terms:

surface tension, polarity, specific heat capacity, boiling point, heat of vaporization, aqueous solution, solute, solvent, solution, solvation, electrolyte, nonelectrolyte, weak electrolyte, strong electrolyte, saturated solution, unsaturated solution, solubility, miscible, immiscible, solubility of a gas, supersaturated solution, molarity, dilute solution, concentrated solution, percent mass, concentration, Arrhenius acid, Arrhenius base, hydronium ion, hydroxide ion, monoprotic, diprotic, triprotic, Bronsted-Lowry acid, Bronsted-Lowry base, conjugate acid, conjugate base, conjugate acid-base pair, amphoteric, self-ionization, neutral solution, ion-product constant for water (Kw), pH, neutralization reaction

Homework: Classwork and Labs

Description / Goals / Score
HW 1 / Ch 15 Water and Aqueous Solutions Worksheet / 1-3 / Unit 9 Note Packet
Solubility of a Salt Activity
HW 2 / Ch 16 Solutions Worksheet / 4-6 / Household chemicals acid/base Activity
Unit 8 – 9 Final Exam
HW 3 / Ch 19 Reading Guide / 7-9
HW 4 / pH, pOH and Concentrations / 10-11

Unit 9

Water, Solutions & Reaction Rates

Notes

15.1 Water and its Properties

Liquid Water and Its Properties

•Many of water’s special properties can be attributed to its ability to hydrogen bond including surface tension, specific heat capacity, and heat of vaporization.

Hydrogen Bond

•

Surface Tension

•

Specific Heat Capacity

•

Heat of Vaporization

•

Liquid Water vs. Solid Water

•Solid water is less dense than liquid water

•Hydrogen bonds force water molecules into a rigid framework as kinetic energy decreases (solid water), leading to a structure with a larger volume than when kinetic energy is higher and water molecules are allowed to slide past one another (liquid water) (see diagram on pg 481)

15.2 Homogeneous Aqueous Solutions

Aqueous Solutions

•Solution –

•Solute –

•Solvent –

•Aqueous Solution –

Solvation

•

•

•

•

Solution Types

  • Solutions can be any type of matter interaction
  • Liquid – Liquid solutions: Miscible (When 2 liquids can’t dissolve: Immiscible)
  • Solid – Solid solutions: Alloys
  • Aqueous: Solution with Water as the Solvent

Electrolyte

•

•

•

•

•

16.1 Properties of Solutions

Factors Affecting Solution Formation

•______ – increases rate of contact between solvent and solute

•Increase in ______ – increases kinetic energy, leading to an increase in the rate of contact between solvent and solute

•Increase in ______– increases the surface contact between solvent and solute

Solubility

•Amount of solute that can be dissolved in a quantity of solvent at a given temperature

•If a solid solute can be dissolved in a liquid solvent then the solute is ______, if it can’t be dissolved the solute is ______

•Solubility represents a Saturated Solution

Solutions

•Saturated Solution – contains the ______amount of solute particles that can be dissolved in a given quantity of solvent at a constant temperature

•Unsaturated Solution – contains less than the ______amount of solute particles that can be dissolved in a given quantity of solvent at a constant temperature

•Supersaturated Solution – contains more than the ______amount of solute particles that can be dissolved in a given quantity of solvent at a constant temperature

Factors Affecting Solubility

•Solubility of a solid solute generally ______with temperature

•Solubility of a gaseous solute ______with temperature, but increases with ______

16.2 Concentrations of Solutions

Concentration of Solutions

•The concentration of a solution is a measure of the amount of solute that is dissolved in a given quantity of solvent.

•Molarity (M) or (mol/L) – number of moles of solute that can be dissolved per Volume of solution (in liters)

Molarity Example

•What is the molarity of a 2.0 L solution containing 4.0 molNaCl?

Making Dilutions

•Dilutions are used to make less concentrated solutions by increasing the volume of solvent.

•When making a dilution the number of moles of solute stays CONSTANT.

•Moles of solute = molarity (M) x liters of solution (V)

•M1V1 = M2V2

Dilution Example

•How many milliliters of 5.0 M CuSO4 would be needed to prepare 100.0 ml of 0.50 M CuSO4?

Example Problems:

•How many moles of HCl must be added to make 2.0L of a 6.0 Molar Solution of HCl(aq)

•What is the molarity of a solution if enough water is added to 35g of KNO3 to make 550mL of solution?

•How much water must to added to 250mL of 2.0 M KCl to produce 0.75 M KCl?

Percent Solution

•Percent by Volume (% (v/v)) =

(volume of solute)/(volume of solution)x100%

•Percent (mass/volume) (% (m/v)) =

(mass of solute (g))/(volume of solution (ml))x100%

Percent Volume Example

•What is the percent volume of acetone in water if 25 ml of acetone is added to 75 ml of water?

Percent (mass/volume) Example

•What is the % (m/v) of a 100 ml aqueous solution containing 10 g of NaCl?

Example Problems

•Calculate the Molarity if 25.0g of NaCl is dissolved in enough water to make 750mL of NaCl (aq)

•Calculate the %Mass concentration of the solution above.

•Calculate the %Volume when 25mL of Vinegar (C2H4O2) is mixed with 125mL of water

19.1 Describing Acids and Bases

Arrhenius Acids and Bases: (page 646)

Define an Arrhenius Acid-

What is an example of a monoprotic acid?

Diprotic acid?

Triprotic acid?

Only the hydrogens in very polar bonds are ionizable.

Compare:

HCl (hydrochloric acid)

CH4

HC2H3O2 (acetic acid)

Define an Arrhenius Base-

Show an Arrhenius Base Solvating in Water:

NaOH

KOH

Metals will react with water to form bases:

Example: Write the balanced equation for sodium metal reacting with water

Bronsted-Lowry Acids and Bases: (page 649)

  • One problem with the Arrhenius theory is that it is not comprehensive enough:
  • We need a better definition to include more substances that behave like acids and bases, yet don’t start with “H” or end with “OH”
  • For example, NH3 (ammonia) and Na2CO3 (sodium carbonate) are bases, yet don’t end with hydroxide, OH- .

Define: Bronsted-Lowery Acids:

Define: Bronsted-Lowery Bases:

What are conjugates?

Conjugate AcidConjugate Base

Show HCl reacting with water and label the conjugate acid-base pairs:

Show ammonia reaction with water:

define amphoteric:

Problems: (page 652)

7. Determine whether the following acids are monoprotic, diprotic, or triprotic

a. H2CO3b. H3PO4c. HCld. H2SO4

8. Write equation for the ionization of nitric acid in water.

Label the conjugate acid-base pairs.

19.2Hydrogen Ions and Acidity

Hydrogen Ions From Water: (page 653)
Occasionally, the collisions between water molecules are energetic enough that a hydrogen ion is transferred from one water molecule to another.
Show the self ionization of water reaction:

A water molecule that loses a hydrogen ion becomes a ______

A water molecule that gains a hydrogen ion becomes a ______

The self ionization of water occurs only to a small extent: What is the concentration of the hydronium ion or hydroxide ion in pure water at 25 degrees C?

[H3O+] = ______and [OH-] = ______

* the brackets stand for concentration in molarity units.
Why is water said to be neutral?

For aqueous solutions, the product of the hydrogen ion concentration and the hydroxide ion concentration is known as the ion-product constant for water, Kw.
Write the expression for Kw:

In acidic solutions, the [H+] is greater than the [OH-]. Therefore, the [H+] is greater than 1 x10 -7 mol/L. In basic solutions, the [H+] is less than the [OH-].

What is another name for basic solutions? ______

Sample Problem 19.2: (page 655)
If [H+] = 1 x 10 -5 mol/L, is the solution acidic, basic, or neutral? What is the [OH-] of this solution?

Example Problem 10
Classify each solution as acidic, basic, or neutral:

  1. [H+] = 6.0 x 10 –10 M
  2. [OH-] = 3.0 x 10 –2 M
  3. [H+] = 2.0 x 10 –7 M
  4. [OH-] = 1.0 x 10 – 7

The pH Concept: (page 656)

Since the hydrogen ion concentration in moles per liter is inconvenient to use, a more widely used system, called the pH scale, is used.
Write the formula for calculating pH:

Sample Problem 19.3 (page 657)
What is the pH of a solution with a hydrogen-ion concentration of 4.2 x 10 -10 mol/L?

Example Problems

12 Determine the pH of the following solutions:

a. [H+] = 0.045 M

b. [H+] = 8.7 x 10 –6 M

c. [H+] = 0.0015 M

d. [H+] = 1.2 x 10 –3 M

13. What are the pH values of the following solutions?

a. [H+] = 1.0 x 10-12 M

b. [H+] = 1.0 x 10 –4 M

Calculating [H+] from pH:
Rearrange the pH equation to solve for [H+]

Sample Problem 19.4 (page 658)
The pH of a solution is 6.35. What is the hydrogen ion concentration?

Example Problems

14. Calculate [H+] for each solution:

  1. pH = 5.00
  1. pH = 12.83

15. What are the hydrogen ion concentrations of:

  1. pH = 4.00
  1. pH = 11.55

Calculating pH from [OH-]
How do you calculate [H+] from [OH-]?

Sample Problem 19.5
What is the pH of a solution if the [OH-] = 4 x 10 -11 ?

Example Problems

16. Calculate the pH for each solution:

a. [OH-] = 4.3 x 10 –5 M

b. [OH-] = 4.5 x 10 -11 M

17. Calculate the pH for each solution:

a. [OH-] = 5.0 x 10 –9 M

b. [OH-] = 8.3 x 10 –4 M

19.4Neutralization Reactions

Acid- Base Reactions:
What is a neutralization reaction?

Identify the products and write balanced equations for the following neutralization reactions:

a. ___ HCl + ___ NaOH 

b. ___H2SO4 + ____ NaOH 

c. ___HCl + ___Ca(OH)2