Presentation on theme: "Acids & Bases They are everywhere.. In your food In your house EVEN IN YOU!!!!!"— Presentation transcript:
Acids & Bases They are everywhere.. In your food In your house EVEN IN YOU!!!!!
What is an acid? An acid is a solution that has an excess of H + ions. It comes from the Latin word acidus that means "sharp" or "sour". The more H + ions, the more acidic the solution.
Properties of Acids Taste sour Conduct electricity Corrosive, which means they break down certain substances. Many acids can corrode fabric, skin, and paper Picture from BBC Revision Bites http://www.bbc.co.uk/schools/ks3bitesize/science/chemistry/acids_b ases_1.shtml http://www.bbc.co.uk/schools/ks3bitesize/science/chemistry/acids_b ases_1.shtml
Properties of Acids Some acids react strongly with metals and form hydrogen gas React with bases to form salts and water Turn blue litmus paper red Picture from BBC Revision Bites http://www.bbc.co.uk/schools/ks3bitesize/science/chemistry/acids_b ases_1.shtml http://www.bbc.co.uk/schools/ks3bitesize/science/chemistry/acids_b ases_1.shtml
Uses of Acids Acetic acid - vinegar Citric acid - lemons, limes, & oranges. Ascorbic acid - Vitamin C which your body needs to function. Sulfuric acid is used in the production of fertilizers, steel, paints, plastics, and in car batteries. Hydrochloric acid – stomach acid
What is a base? A base is a solution that has an excess of OH - ions. Another word for base is alkali.
Properties of a Base Feel slippery Taste bitter Caustic, which means they break down certain substances. Conduct electricity. (Think alkaline batteries.)
Properties of a Base Do not react with metals. React with acids to produce salts and water. Turns red litmus paper blue.
Uses of Bases Bases – found in soaps, ammonia, and many other cleaning products. The OH- ions interact strongly with substances, such as dirt and grease. Chalk and oven cleaner contain bases. Blood is a basic solution.
Acids and Bases – electrical conductors Acids and bases both can conduct electricity because both contain ions Ionic solutions are electrolytes - any substance containing free ions that make the substance electrically conductive
pH Scale pH is a measure of how acidic or basic a solution is. The pH scale ranges from 0 to 14. Acidic solutions have pH values below 7 Solutions with a pH of 0 are very acidic.
pH Scale A solution with a pH of 7 is neutral. Pure water has a pH of 7. Basic solutions have pH values above 7. Solutions with a pH of 14 are very basic
pH Scale A change of 1 pH unit represents a tenfold change in the acidity of the solution.
pH Scale For example, if one solution has a pH of 1 and a second solution has a pH of 2, the first solution is not twice as acidic as the second—it is ten times more acidic.
Weak vs. Strong Acids Strong acids ionize completely when placed in water. HCl, HNO 3, H 2 SO 4, HClO 4, HI, HBr HCl H + + Cl - Weak acids do not ionize completely, they remain mostly intact and release fewer H + ions CH 3 COOH ↔ CH 3 COO - + H +
Weak vs. Strong Baces Strong bases ionize completely when placed in water. NaOH, LiOH, Be(OH) 2, Mg(OH) 2 Mg(OH) 2 Mg 2+ + 2(OH) - Strong bases remove more H + ions when they are mixed with water (the OH - ions react with the H + ions) Weak bases do not ionize completely, they remain mostly intact and release fewer OH - ions and remove fewer H + ions when they are mixed with water NH 3 + H 2 O ↔ NH 4 + + OH -
Acid – Base Reactions A reaction between an acid and a base is called neutralization. An acid-base mixture is not as acidic or basic as the individual starting solutions.
Acids and Bases react to form salts When an acid and a base react, H + ions and OH - ions react to produce water and decrease the concentration of H + ions The anions and cations that were connected with the H + ions and OH - ions react to form salts. NaOH + HCl Na + + Cl - + H + + OH - NaOH + HCl NaCl + H 2 O
Acid – Base reactions Each salt listed in this table can be formed by the reaction between an acid and a base. Salts are very important chemicals
Serial Dilution Serial dilution is the stepwise dilution of a substance in solution.