Presentation on theme: "WHAT IS PH? Concentration and hydrogen ions and hydroxide ions are a measure of The acidity and alkalinity of a solution."— Presentation transcript:
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 M [OH - ] = 1 x M Therefore: [H + ] x [OH - ] = 1 x M
[H + ]X [OH - ] = 1 X M Is called the Ion-product constant AKA: k w
ION PRODUCT CONSTANT K w = 1 x M
ACIDITY IS A MEASURE OF THE [H + ] OF A SOLUTION. If the [H + ] of a solution is 1.0 x M, is the solution acidic, basic or neutral? 1.0x M is greater than 1.0 x M Therefore the solution is acidic
PRACTICE: ACIDIC, BASIC OR NEUTRAL? 1.[H + ] = 6.0 x M 2.[H + ] = 2.0 x M 3.[OH - ] = 1.0 x M
SOLVE THESE PROBLEMS USING K W = [H + ] X [OH - ] AND DETERMINE WHETHER SOLUTION IS ACIDIC, NEUTRAL OR BASIC 1.[OH - ] = 1 x [OH - ] = 2.0 x [OH - ] = 3.5 x 10 -7
THE PH SCALE Ranges from – 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 M 2.[H + ] = 1.0 x M 3.[H + ] = 1.0 x M 4.[H + ] = 1.0 x M 5.[H + ] = 1.0 x M
GET YOUR CALCULATORS OUT AND PRACTICE. 1.[H + ] = M 2.[H + ] = 8.7 x M 3.[H + ] = M 4.[H + ] = 1.2 x M
ANSWERS 1.PH = PH = PH = PH = 2.92
FIND THE PH AND DETERMINE IF IT IS ACID BASIC OR NEUTRAL [H + ] = 1.5 x [H + ] = 3.4 x [H + ] = 5.5 x [H + ] = 1.0 x 10 -7
YOU CAN ALSO CALCULATE PH FROM [OH - ] If you are given [OH - ] use [H + ] = 1 x [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 A solution has a hydrogen ion concentration of [H + ] = 5.0 x Is it acidic, basic or neutral?