Chemistry Acids & Bases

Properties of acids and bases Electrolytes Taste sour Turn litmus paper red 0-6.9 on pH scale React with metals to form Hydrogen gas (H2) Form H+ ions when in water Examples: vinegar, milk, soda, apples, citrus fruits Electrolytes Taste bitter Turn litmus paper blue 7.1-14 on pH scale Feels slippery Form OH- ions when in water Examples: ammonia, lye, antacid, baking soda

pH scale Label the pH scale from 0-14 Label the scale where the following terms would be found Strong acid Weak acid Strong base Weak base Neutral

Acid or Base? Classify the following pH values: pH = 1 pH = 13 pH = 8 pH = 3 pH = 6 pH = 10

Acid or Base? Classify the following pH values: pH = 1 pH = 13 pH = 8 pH = 3 pH = 6 pH = 10 Acid Base

pH of common substances

B. pH Scale- ions in solution EX: pH = -log[H3O+] pOH = -log[OH-] pH + pOH = 14 [H+] = 1 x 10-9 [H+] = 1 x 10-3 [H+] =1 x 10-7 [OH-] = 1 x 10-9 [OH-] = 1 x 10-3 Acids/bases dissociate into their prospective ions when in solution. This makes them conduct a current TOO! Since there are + and – ions in solution, they are electrolytes!!

Draw HCl (hydrochloric acid) dissociating into it’s ions: Draw NaOH (sodium hydroxide) dissociating into it’s ions:

Properties of acids and bases: Get 8 test tubes. Rinse all tubes well with water. Add 2 droppers full acid to four tubes, 2 droppers full of base to the other four. Touch a drop of base to your finger. Record the feel in the chart (on the next slide). Wash your hands with water. Repeat for acid. Use a stirring rod, drip a drop of base to the litmus and pH papers (for pH paper use a color key to find a number). Record results. Repeat for acid. into the four base tubes add: a) one drops of phenolphthalein, b) one drop of bromothymol blue c) a piece of Mg, d) a small scoop of baking soda. Record results. Cleanup (wash tubes, pH/litmus paper in trash). Wipe down tables. Wash hands

Activity: base acid

Lab roles-write who Label test tubes Label pipettes Get materials EVERYONE rinses glassware