WHAT IS PH?Concentration and hydrogen ions and hydroxide ions are a measure of

The acidity and alkalinity of a solution.

HOW WAS THE CONCEPT OF PH DEVELOPED?

H2 O is a molecule.Therefore, pure water

does not conduct electricity.

OR DOES IT?

When pure water was found to conduct very small currents of electricity, the self-ionization of water was discovered.

SELF-IONIZATION OF WATER

H2 O H+ + OH-

Water can dissociate into Hydronium ions and hydroxide ions.

HOW MUCH DISSOCIATION IS THERE?

[H+] = 1 x 10-7 M[OH-] = 1 x 10-7 M

Therefore:[H+] x [OH-] = 1 x 10-14 M

[H+]X [OH-] = 1 X 10-14 M

Is called theIon-product constantAKA: kw

ION PRODUCT CONSTANT

Kw = 1 x 10-14 M

ACIDITY IS A MEASURE OF THE [H+] OF A SOLUTION.

If the [H+] of a solution is 1.0 x 10-5M, is the solution acidic, basic or

neutral?

1.0x 10-5 M is greater than 1.0 x 10-7 M

Therefore the solution is acidic

PRACTICE: ACIDIC, BASIC OR NEUTRAL?

1. [H+] = 6.0 x 10-10M2. [H+] = 2.0 x 10-7 M3. [OH-] = 1.0 x 10 -7 M

SOLVE THESE PROBLEMS USING KW = [H+] X [OH-] AND DETERMINE WHETHER

SOLUTION IS ACIDIC, NEUTRAL OR BASIC

1. [OH-] = 1 x 10-3

2. [OH-] = 2.0 x 10-11

3. [OH- ] = 3.5 x 10-7

THE PH SCALE

Ranges from 0 -14.0 – 6.9 = acidic7.0 = neutral

7.1 – 14.0 = basic (alkaline)

SO WHERE DO THESE NUMBERS COME FROM?

pH = - log [H+]

That’s where they come from!

WHAT IS THE PH?

1. [H+] = 1.0 x 10- 4 M2. [H+ ] = 1.0 x 10 -2 M3. [H+] = 1.0 x 10 -10 M4. [H+] = 1.0 x 10-7 M5. [H+] = 1.0 x 10-14 M

ANSWERS

1. 42. 23. 104. 75. 14

GET YOUR CALCULATORS OUT AND PRACTICE.

1. [H+] = 0.0045 M2. [H+] = 8.7 x 10-6 M3. [H+] = 0.0015M

4. [H+] = 1.2 x 10-3 M

ANSWERS

1. PH = 2.352. PH = 5.063. PH = 2.824. PH = 2.92

FIND THE PH AND DETERMINE IF IT IS ACID BASIC OR NEUTRAL

•[H+] = 1.5 x 10-9

•[H+] = 3.4 x 10-2

•[H+] = 5.5 x 10-11

•[H+] = 1.0 x 10-7

YOU CAN ALSO CALCULATE PH FROM [OH- ]

If you are given [OH-] use [H+] = 1 x 10-14 [OH-]

To find hydrogen ion concentration then solve for pH

pH = –log [H+]

LET’S PRACTICE

Calculate the pH of a solution with a [OH-] of 3.5 x 10-9

EXIT SLIP: YOUR NAME HERE……

1. Find the pH of a solution with an hydroxide concentration of [OH-] = 2.9 x 10-5

2. A solution has a hydrogen ion concentration of [H+] = 5.0 x 10 -12 . Is it acidic, basic or neutral?

BRAINPOP