p H Indicators and Titrations Chemistry Joke Special

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p. H, Indicators, and Titrations

p. H, Indicators, and Titrations

Chemistry Joke

Chemistry Joke

Special thanks to Kate Pancho!

Special thanks to Kate Pancho!

Definition of p. H � p. H is a number scale from 0 –

Definition of p. H � p. H is a number scale from 0 – 14 that represents the acidity or basicity of a solution. � 0 – 6 is acidic � 7 is neutral � 8 – 14 is basic

Definition of p. H � p. H is a measure of the hydrogen ion

Definition of p. H � p. H is a measure of the hydrogen ion concentration of a solution � p. H = - log [H+] � The lowercase p stands for negative log � [H+] represents the concentration of hydrogen ions in units of molarity (mol/L)

Definition of p. OH � p. OH is also a number scale that represents

Definition of p. OH � p. OH is also a number scale that represents acidity or basicity of a solution. � It is the opposite of the p. H scale � p. OH is a measure of the hydroxide ion concentration of a solution. � p. OH = - log [OH-]

p. H and p. OH � p. H + p. OH = 14 �

p. H and p. OH � p. H + p. OH = 14 � [H+] [OH-] = 1 x 10 -14 M � If [H+] increases, [OH-] must decrease.

Calculating p. H and p. OH � If [H+] is 10 -5 M, the

Calculating p. H and p. OH � If [H+] is 10 -5 M, the p. H is 5. › Is this acidic, basic, or neutral? � If the p. H is 5, what is the p. OH? › p. H + p. OH = 14, so the p. OH = 9. � If [H+] is 10 -7 M, what is the p. H? › Is this acidic, basic or neutral? � If the p. H is 7, what is the p. OH?

Calculating p. H and p. OH � If [OH-] = 10 -5 M, what

Calculating p. H and p. OH � If [OH-] = 10 -5 M, what is the p. OH? � If [OH-] = 10 -6 M, what is the p. H? › The p. OH = 6, so the p. H = 8 � If the hydrogen ion concentration is 1 x 10 -4 M, is the solution acidic, basic, or neutral? › p. H = 4, so acidic � If the hydroxide ion concentration is 1 x 10 -5 M, is the solution acidic, basic, or neutral? › p. OH = 5; p. H = 9, so the solution is basic

Calculating [H+] and [OH-] � Remember that 10 a x 10 b = 10(a+b)

Calculating [H+] and [OH-] � Remember that 10 a x 10 b = 10(a+b) � If [OH-] = 10 -6 M, what is the [H+]? › [H+] [OH-] = 1 x 10 -14 M › [H+] = 10 -8 M � If [H+] = 10 -9 M, what is the [OH-]? › [OH-] = 10 -5 M � Fill in the chart on your notesheet.

Indicators � An indicator is a compound that changes color within a specific p.

Indicators � An indicator is a compound that changes color within a specific p. H range. � Some common indicators: › Phenolphthalein—colorless to bright pink at a p. H range of 8 – 10. › Alizarin yellow—yellow to lilac at a p. H range of 10 – 12 › Bromphenol blue—yellow to blue at a p. H range of 3 - 4

Indicator Demo

Indicator Demo

Titrations � Titration is a method used to determine the concentration of [H+] or

Titrations � Titration is a method used to determine the concentration of [H+] or [OH-]. � Procedure: › 1. Measure a volume of acidic solution of unknown concentration. › 2. Add an indicator to the solution. › 3. Add, drop by drop, a measured volume of base of known concentration just until the indicator turns color.

Titrations � The solution of known concentration is called the standard solution. � The

Titrations � The solution of known concentration is called the standard solution. � The point where the indicator changes color is called the end point. � Once the titration is complete, the unknown molarity of the acid can be calculated. � MA x V A = M B x V B › Molarity of acid x volume of the acid is equal to the molarity of the base x the volume of the base.

Titration Demo

Titration Demo

Chemistry Joke Q: What is this? A: A fish out of water!!

Chemistry Joke Q: What is this? A: A fish out of water!!