1. Acids and Bases

2. Acids Acids are substances that release hydrogen ions, H +, in solution Acids are substances that release hydrogen ions, H +, in solution Acids can be recognized because their chemical formulas start with the symbol for hydrogen, H Acids can be recognized because their chemical formulas start with the symbol for hydrogen, H HCl – hydrochloric acid HCl – hydrochloric acid H 2 SO 4 – sulfuric acid H 2 SO 4 – sulfuric acid HNO 3 – nitric acid HNO 3 – nitric acid

3. Bases Bases are substances that release hydroxide ions, OH -, in solution Bases are substances that release hydroxide ions, OH -, in solution Many bases can be recognized because their chemical formulas end with OH Many bases can be recognized because their chemical formulas end with OH NaOH – sodium hydroxide NaOH – sodium hydroxide Ca(OH) 2 – Calcium hydroxide Ca(OH) 2 – Calcium hydroxide

4. Bases A base can also be called an alkali A base can also be called an alkali Remember the alkali metals – which group? Remember the alkali metals – which group? Combine with hydroxide to form the strongest bases Combine with hydroxide to form the strongest bases

5. The pH Scale Used to show the strength of an acidic or basic solution Used to show the strength of an acidic or basic solution Measures the concentration of H + ions in solution Measures the concentration of H + ions in solution An acid has a pH<7 An acid has a pH<7 A base has a pH>7 A base has a pH>7 Pure water has pH=7 (the concentrations of H + and OH - ions are equal) Pure water has pH=7 (the concentrations of H + and OH - ions are equal)

6. The pH Scale pH can be determined by using pH can be determined by using Indicators (such as phenolphthalein) Indicators (such as phenolphthalein) Litmus and pH papers (contain chemicals that turn certain colors in the presence of acids or bases) Litmus and pH papers (contain chemicals that turn certain colors in the presence of acids or bases) pH meter pH meter

7. The pH Scale The concentration of H + ions is inversely proportional to the concentration of OH - ions The concentration of H + ions is inversely proportional to the concentration of OH - ions As the concentration of H + ions increases, the concentration of OH - ions decreases As the concentration of H + ions increases, the concentration of OH - ions decreases As the concentration of OH - ions increases, the concentration of H + ions decreases As the concentration of OH - ions increases, the concentration of H + ions decreases

8. pH of Household Chemicals You might be surprised to know that many household items are acids and bases. You might be surprised to know that many household items are acids and bases. We can use litmus paper and indicator to find out which are acids and which are bases. We can use litmus paper and indicator to find out which are acids and which are bases.

9. Conductivity Solutions that conduct electricity are called electrolytes Solutions that conduct electricity are called electrolytes In order to conduct electricity, there must be charged particles in the solution In order to conduct electricity, there must be charged particles in the solution Which things will conduct electricity? Which things will conduct electricity? WaterSalt WaterSalt SugarBaking soda SugarBaking soda Vinegar Vinegar

10. Conductivity Solutions that conduct electricity are called electrolytes Solutions that conduct electricity are called electrolytes In order to conduct electricity, there must be charged particles in the solution In order to conduct electricity, there must be charged particles in the solution Which things will conduct electricity? Which things will conduct electricity? Salt Salt Sugar Sugar Acids and bases both conduct electricity because they form ions in solutions Acids and bases both conduct electricity because they form ions in solutions

11. Other Properties Acids are corrosive, bases are caustic (both can cause burns) Acids are corrosive, bases are caustic (both can cause burns) Acids taste sour (think lemon juice or vinegar) Acids taste sour (think lemon juice or vinegar) Bases taste bitter (ever tried plain baking soda?) Bases taste bitter (ever tried plain baking soda?) Bases feel slippery because they react with the fats in your skin to make soap Bases feel slippery because they react with the fats in your skin to make soap

12. Neutralization Reactions Acids and bases combine to form a salt and water Acids and bases combine to form a salt and water This is called neutralization and is a double replacement reaction This is called neutralization and is a double replacement reaction HCl + NaOH  NaCl + H 2 O acidbase saltwater When the reaction is complete, the pH will be 7, or neutral