Acids and Bases Unit 13

Acids

1) Acids start with hydrogen, and some react with active metals to liberate hydrogen gas. Ba (s) + H 2 SO 4(aq) BaSO 4 (aq) + H 2(g)

Properties of Acids 2) Acids change the color of dyes known as “acid-base indicators” Acids turn litmus paper turns red.

Properties of Acids 1) Acids have a sour taste.

Properties of Acids 4) Acids react with bases to produce salt and water. This is a neutralization reaction. Mg(OH) 2 + HCl --> MgCl 2 + HOH

5) Acids conduct electrical currents in an aqueous solution. Acids are electrolytes.

6) Acids produce hydrogen ions when dissolved in water.

Bases

1) End with (OH) hydroxide

2) Change the color of acid- base indicators litmus paper: red  blue

3) Bases feel slippery.

Properties of Bases 4) Bases react with acid to produce salt and water. This is called neutralization reaction. 5) Bases are electrolytes. What?

6) Bases produce hydroxide ions when dissolved in water. 6) Bases produce hydroxide ions when dissolved in water.

Neutralization Reactions A reaction between traditional acids (hydrodium ions) and bases (hydroxide ions) produces water and one of a class of compounds called salts A reaction between traditional acids (hydrodium ions) and bases (hydroxide ions) produces water and one of a class of compounds called salts H 3 O+(aq) + OH−(aq)  2H 2 O(l) H 3 O+(aq) + OH−(aq)  2H 2 O(l)

Acid Base Reactions 1. Salt- ionic compound composed of a OH - from an Arrhenius base and an H 3 O + from an Arrhenius acid 1. Salt- ionic compound composed of a OH - from an Arrhenius base and an H 3 O + from an Arrhenius acid 2HNO 3 + Ca(OH) 2 Ca 2+ (NO 3 - ) 2 + 2HOH 2HNO 3 + Ca(OH) 2 Ca 2+ (NO 3 - ) 2 + 2HOH H 2 S + 2NaOH Na 2 + S HOH H 2 S + 2NaOH Na 2 + S HOH Double Replacement Double Replacement

Acids & Bases pH How We Measure Acids and Bases

What is pH? A pH scale is how we measure how acidic or basic something is. When we dissolve an acid in water, it ionizes and produces excess Hydrogen Ions, H + pH is formally how we measure the activity of those Hydrogen Ions in solutions.

Where Do Common Substances Fall on the Scale? pH is a range that usually is expressed as going from 0 to 14, though it can go beyond that range.

Acid Rain Normal rain pH of 5.3 Normal rain pH of 5.3 Acid rain pH of Acid rain pH of

Acid Rain Man-Made Causes Man-Made Causes – Burning of fossil fuels (coal production – yucky!) –carbon dioxide + water => carbonic acid

Traditional Acid  Definition: An Arrhenius acid is a chemical compound that increases the concentration of hydrogen ions, H+, in aqueous solution.  HNO 3 + H 2 O  H 3 O + + NO 3 -

B. Acid- Base reactions- Arrhenius (traditional) Acid – Base Reactions 1. An acid-base reaction occurs in aqueous solution between a strong Arrhenius acid that completely dissociates to produce H 3 O +, and a strong Arrhenius base that completely dissociates to produce OH − 1. An acid-base reaction occurs in aqueous solution between a strong Arrhenius acid that completely dissociates to produce H 3 O +, and a strong Arrhenius base that completely dissociates to produce OH − HCl(aq) + NaOH(aq)  NaCl(aq) + H 2 O(l) HCl(aq) + NaOH(aq)  NaCl(aq) + H 2 O(l)

 c. Their water solutions are known as aqueous acids. All pure aqueous acids are electroytes.  HNO3(l) + H2O(l) H3O+(aq) + NO3−(aq)  HCl(g) + H2O(l) H3O+(aq) + Cl−(aq)

Traditional Bases Arrhenius base is a substance that contains hydroxide ions (OH - ) and dissociates to produce hydroxide ions (OH-) into solutions Arrhenius base is a substance that contains hydroxide ions (OH - ) and dissociates to produce hydroxide ions (OH-) into solutions NaOH(s) Na+(aq) + OH−(aq) NaOH(s) Na+(aq) + OH−(aq)