# WHAT IS PH? Concentration and hydrogen ions and hydroxide ions are a measure of The acidity and alkalinity of a solution.

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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? H 2 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 H 2 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 the Ion-product constant AKA: k w

ION PRODUCT CONSTANT K w = 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 -5 M, 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 -10 M 2.[H + ] = 2.0 x 10 -7 M 3.[OH - ] = 1.0 x 10 -7 M

SOLVE THESE PROBLEMS USING K W = [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 = acidic 7.0 = 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 M 2.[H + ] = 1.0 x 10 -2 M 3.[H + ] = 1.0 x 10 -10 M 4.[H + ] = 1.0 x 10 -7 M 5.[H + ] = 1.0 x 10 -14 M

ANSWERS 1.4 2.2 3.10 4.7 5.14

GET YOUR CALCULATORS OUT AND PRACTICE. 1.[H + ] = 0.0045 M 2.[H + ] = 8.7 x 10 -6 M 3.[H + ] = 0.0015M 4.[H + ] = 1.2 x 10 -3 M

ANSWERS 1.PH = 2.35 2.PH = 5.06 3.PH = 2.82 4.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

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