pH

Acids Anything that produces H 3 O+ ions if dissolved in water Taste sour Turns blue litmus paper red When acids dissolve in water, it donates a H+ion to H 2 O Example HCl

Strong acids Strong acids separate into ions completely in water Ex: all HCl molecules separate into H+ and Cl- ions in water

Weak acids When placed in water, most weak acid molecules stay intact Ex: only a few vinegar molecules (acetic acid, HC 2 H 3 O 2 ) will separate into ions in water

Bases Any substance that produces OH- ions in water Feels slippery (like soap), tastes bitter Turns red litmus paper blue Usually found in cleaners Ex: NaOH

Strong and Weak Bases If placed in water strong bases separate completely into OH- ions Weak bases only occasionally make OH- ions when placed in water Weak does not = unimportant. Most of bodys acid/base reactions require weak acids or bases

Acid/Base reactions Acids and bases react together in certain proportions to form salts The reactions between acids and bases are called neutralization reactions Real-life examples (heartburn) and antacids

pH scale The pH scale measures the amount of H 3 O+ in a solution pH of 1 means the solution has a lot of H 3 O+ pH of 14 means the solution has molecules of H 3 O

Indicators of pH Indicators- substances that change color in the presence of acids and bases Ex: litmus paper- red paper turns blue in presence of base- blue paper turns red in the presence of an acid Red cabbage is also a natural indicator Indicators have no impact on the reactions of acids and bases

Acids and bases in the body Stomach acid (HCl) has a pH of 1-2 and is used in digestion- the mucous lining in the stomach protects the stomach Pancreas and liver release a base to neutralize acid when it enters the intestines pH of blood is regulated by your breathing CO 2 makes blood more acidic

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