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Acid and Base Reactions Unit 2 Chemistry. Common Acids  Occur naturally in fruits.  Produced by bacteria in milk (that is why milk turns sour).  Insects.

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Presentation on theme: "Acid and Base Reactions Unit 2 Chemistry. Common Acids  Occur naturally in fruits.  Produced by bacteria in milk (that is why milk turns sour).  Insects."— Presentation transcript:

1 Acid and Base Reactions Unit 2 Chemistry

2 Common Acids  Occur naturally in fruits.  Produced by bacteria in milk (that is why milk turns sour).  Insects such as millipedes, scorpions and ants use acid to deter their predators.  Lemons.  Vinegar.  Stomach acid.  Lactic acid in your muscles: when you exercise and use up the oxygen in your muscles, lactic acid is given off as a byproduct of metabolism and when too little oxygen is available the lactic acid will build up and cause your muscles to feel heavy and sore.

3 Common Bases:  Bitter tasting compound with a slippery feel.  Most soaps and drain cleaners, window cleaners (ammonia).  Sea water is slightly basic. Most acids and bases dissolve in water. The delicate balance between acids and bases is vital for organisms (especially humans) to survive.

4 Lab Mock Apple Pie Bottle Rockets

5 Acids and Bases An Acid is:  a substance that produces hydrogen ions in a solution, H + (aq)  HCl (aq) + H 2 O (aq)→ H + (aq) + Cl - (aq)

6 Acids and Bases A Base is defined as:  A substance that produces hydroxide ions in a solution, OH - (aq)  NaOH (aq) + H 2 O (aq)→ OH - (aq)

7 Indicators Indicators: chemicals that change colour as the concentration of H + (aq) or OH - (aq) changes. Indicators change colour at specific concentrations of H+ ions in solution. They are used to measure the acidity of solutions. Electronic pH meters read the acidity directly.

8 Indicators Two common indicators are  Phenolphthalein  Litmus (extracted from lichens, plant-like member of fungi kingdom)  Natural indicators such as cabbage juice Litmus turns pink under acid conditions and blue in basic conditions.

9 pH Scale The pH scale is used to describe if a solution is an acid or a base A pH of 7 is neutral; that is, the concentrations of H+ and OH- are equal. A pH of is acidic A pH of is basic Textbook page 219

10 Acid Rain Uncontaminated rainwater has a pH of about 5.5 Rainwater with a pH below 5.5 is called acid rain because it is more acidic than normally would be expected naturally. Acid rain is affecting:  Non-living: buildings, monuments, stone structures.  The biosphere: lakes, rivers and oceans, fish and ocean species are at risk.  Plant life: trees, algae and other producers.

11 Indicator Lab- testing pH of common household substances


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