The Ion Product Constant for Water (Kw)

Slides:

Advertisements

Similar presentations

Hydrogen Ions and Acidity

Advertisements

PH and Concentration. pH Recall water H 2 O H + + OH - Every water molecule produces one hydrogen ion and one hydroxide ion At equilibrium, K eq = [products]

PH (potential of Hydrogen). According to the Bronsted-Lowry theory, both acids and bases are related to the concentration of hydrogen ions. Acids will.

Aqueous solutions & concepts of pH Chapter I. Ion Product constant - water A.  Acids→ hydronium ions (H 3 O+)  Bases → hydroxide ions (OH-) B.Self.

Chapter 16: Equilibrium in Acid-Base Systems 16.1a: Self-ionization of Water K w pH and pOH.

Chemistry Chapter Acids and Bases. (Self-Ionization of Water) H 2 O + H 2 O  H 3 O + + OH -  Two water molecules collide to form Hydronium and.

Ch.15: Acid-Base and pH Part 1.

How is pH defined? The pH of a solution is the negative logarithm of the hydrogen-ion concentration. The pH may be represented mathematically, using the.

Self-ionization of Water and pH Objectives: 1. Identify the ions present in pure water and give their concentrations. 2. Define pH and explain how the.

Acid / Base Equilibria A Practical Application of the Principles of Equilibrium.

8.2 Strong and Weak Acids and Bases

Strong Acid-Base Calculations

Calculating pH and pOH. pH pH = - log [H + ] [H + ] = the hydrogen ion concentration pH: “potential of hydrogen” - A way of expressing the hydrogen ion.

Acid-Base Titration and pH

PH Chapter Vocabulary Word hydronium ion: H 3 O + hydroxide ion: OH -

Auto dissociation of Water Water molecules allow protons to be transferred between molecules & an equilibrium is established. HOH (l) + HOH (l) H 3 O +

Chapter 19 More about ACID-BASES. Self-Ionization of Water Two water molecules produce a hydronium ion & a hydroxide ion by the transfer of a proton.

Equilibrium. Chemical Equilibrium Review Most chemical reactions do not go to completion. They appear to stop. These reactions are reversible A chemical.

What is pH?. Ion Product Constant for Water  H 2 O(l)  H + (aq) + OH - (aq)  Keq = Kw = [H + ] x [OH - ]  The ion product constant for water (Kw)

How is pH defined? The pH of a solution is the negative logarithm of the hydrogen-ion concentration. The pH may be represented mathematically, using the.

The Equilibrium of Weak Acids and Bases. The dissociation of an acidic or basic compound in aqueous solution produces ions that interact with water (REVIEW!)

Note Guide 10-2 Hydrogen Ions from water (water molecule highly polar) --A water molecule that loses a hydrogen ion becomes a negatively charged hydroxide.

Ch. 15 Titration And pH. Ionization of Water _____________________: two water molecules produce a hydronium ion and a hydroxide ion by transfer of a proton.

- Strong Acids & Bases – - - Autoionization of Water - 1.

Review 1: Written the conjugate base and acid for the following acids and bases.

Acids and Bases. Some Properties of Acids þ Produce H + (as H 3 O + ) ions in water (the hydronium ion is a hydrogen ion attached to a water molecule)

PH. The Ion product constant for water H 2 O (l) + H 2 O (l)  H 3 O + (aq) + OH − (aq) Dissociation of water is an equilibrium, and since liquid water.

Yesterday’s Homework Page 611 # 19 Page 612 # 20.

Ch. 15 & 16 - Acids & Bases II. pH (p ) C. Johannesson.

NOTES: 19.2 – Hydrogen Ions & Acidity (pH and pOH)

Acids & Bases pH. Ionization of Water H 2 O + H 2 O H 3 O + + OH - K w = [H 3 O + ][OH - ] = 1.0  Kw=ionization constant for H2O.

Aqueous Solutions and the Concept of pH Section 15.1.

Section 16.2 Determining the Acidity of a Solution 1.To understand and determine pH and pOH 2.To learn methods for measuring pH of a solution Objectives.

K w, pH, and pOH. IONIZATION OF WATER Water is capable of reacting with itself in an ionization reaction H 2 O (l) + H 2 O (l) ⇌ H 3 O + (aq) + OH - (aq)

Acids & Bases Lesson 6 Strong Acid-Base Calculations.

Strong and Weak Acids and Bases

Acid-Base Titration and pH 1. What ions are associated with acids? Bases? 2.What mathematical operation is the pH scale based on? 3.What is the pH scale?

PH. Ionization of Water  When compounds dissociate/ionize in an aqueous solution, they produce ions - hydronium (H 3 O + ) and hydroxide (OH - )  These.

Acids, Bases, and pH.

The pH Scale Hydronium & Hydroxide Ions (H3O+) (OH–) pH Scale

Self Ionization of Water and the pH Scale

SELF-IONIZATION OF WATER

Ionization Constant of Water

Hydronium Ions and Hydroxide Ions

Hydronium Ions and Hydroxide Ions

Chapter 9 Acids and Bases

Can you calculate for acids and bases?

Calculating Concentration

The pH Scale Hydronium & Hydroxide Ions (H3O+) (OH–) pH Scale

Chapter 15 Preview Lesson Starter Objectives

Unit 14 – Acid, Bases, & Salts

Unit 13 – Acid, Bases, & Salts

Calculating Concentration

Chapter : Acids and Bases

Calculating pH from the Water Constant

PH and Concentrations.

Lesson # 7 Equilibrium & pH

Carrying on with Acid-Base (Part 2)

6.2 pH and pOH calculations A. Ion Concentration in Water

Unit 13 – Acid, Bases, & Salts

Acids Lesson 8 Ionization of Water pH Calculations.

Calculating pH (and pOH)

Unit 15 – Acid, Bases, & Salts

Unit 13 – Acid, Bases, & Salts

Unit 14 – Acid, Bases, & Salts

Conjugate Acids and Bases

Unit 13 – Acid, Bases, & Salts

Presentation transcript:

The Ion Product Constant for Water (Kw)

Pure water dissociates according to the following reaction: H2O(l)  H+(aq) + OH-(aq) There is an equal amount of H+ and OH- ions in solution (neutral, pH = 7) at 25°C [H+] = [OH-] = 1x10-7 mol/L equilibrium constant for the dissociation of water: Kw Kw = [H+][OH-] = (1x10-7)(1x10-7) = 1x10-14 * small k, reactants are favoured (does not go to completion)

Since strong acids and bases dissociate completely in water, [H+] = [acid] @ 25°C acids: [H+] > [OH-] [H+] > 1x10-7 [OH-] < 1x10-7 bases: [OH-] > [H+] [H+] < 1x10-7 [OH-] > 1x10-7 We can use Kw to calculate [H+] and [OH-] in solutions

Ex 1) Find the [H+] and [OH-] in: (a) 2.5 M nitric acid (b) 0.16 M Barium hydroxide (a) HNO3  H+ + NO3- C 2.5 M 2.5 M Kw = [H+][OH-] [OH-] = Kw / [H+] = (1x10-14)/(2.5) = 4x10-15 M (b) Ba(OH)2  Ba2+ + 2 OH- C 0.16 M 0.32 M Kw = [H+][OH-] [H+] = Kw / [OH-] = (1x10-14)/(0.32) = 3.1x10-14 M

pH and pOH pH: The Power of the Hydronium Ion A measure of the amount of H+ ions in a solution Convenient way to represent acidity since [H3O+] is usually a very small number 2 factors determine pH ionization concentration because they both contribute to the number of H+ or OH- molecules in a solution. The practical scale goes from 0  14

pH = -log [H3O+] pOH = -log [OH-] In neutral water, pH = -log [H3O+] = -(log(1 x 10-7) = 7 pOH = -log [OH-] = -(log(1 x 10-7) = 7 Note: pH + pOH = 14, always, regardless of solution! Another way to calculate [H3O+] & [OH-] in solution: [H3O+] = 10-pH [OH-] = 10-pOH

Ex) A liquid shampoo has a [OH-] of 6.8x10-5 mol/L (a) Is the shampoo acid, basic or neutral? (b) What is [H3O+]? (c) What is the pH and pOH of the shampoo? (a) [OH-] = 6.8x10-5 > 1.0x10-7, basic (b) [H3O+] = Kw / [OH-] = (1.0x10-14)/(6.8x10-5) = 1.5x10-10 mol/L (c) pH = -log [H3O+] pOH = -log [OH-] = -log [1.5x10-10] = -log [6.8x10-5] = 9.83 = 4.17 check: 9.83 + 4.17 = 14 !

HOMEWORK P382 #1-4 p390 #9-12 p392 #13-18