1. A CIDS & B ASES Science 10: Chemical Reactions

2. PROPERTIES OF ACIDS A chemical compound that produces hydrogen ions (H + ) when dissolved in water ex.HCl (aq) H + (aq) + Cl - (aq) Sour taste -- some are safe to eat, many are not Many can burn skin Corrosive React with metals Useful for rust removal, and refining/processing metals pH < 7

3. PROPERTIES OF BASES A chemical compound that produces hydroxide ions (OH - ) when dissolved in water ex.NaOH (aq) Na + (aq) + OH - (aq) Bitter taste Slippery feel – many can burn skin Highly corrosive Don’t react with metals Commonly used as cleaning products pH > 7

5. H OW CAN WE TELL IF SOMETHING IS AN ACID OR A BASE ?

6. Most acids and bases are colorless solutions in water. Taste test? Touch?

7. A CID -B ASE I NDICATORS An acid-base indicator is a chemical that is a characteristic color when in the presence of an acid or base. Phenolphthalein is a chemical compound that turns pink or fuchsia in basic solutions. There are many acid-base indicators found in nature ex. blueberries, beets, rose petals, red cabbage, and strawberries.

8. H YDRANGEA F LOWERS If grown in basic soil hydrangeas are pink. If grown in acidic soil the flowers are blue.

9. L ITMUS Blue litmus paper turns red in an acidic solution. Red litmus paper turns blue in a basic solution. Neutral solution = neither type changes color

10. L ITMUS Blue litmus paper turns red in an acidic solution. Red litmus paper turns blue in a basic solution. Neutral solution = neither type changes color It can’t tell us how acidic or basic something is though. Qualitative or Quantitative?

11. T HE P H S CALE Used for identifying a solution as acidic, basic, or neutral. Ranges from 0 to 14 The pH value of a solution is a number that expresses the concentration of H + ions in a solution.

12. T HE P H S CALE

13. Acidic Solutions: pH <7 The more acidic a solution, the lower the pH value. This means a higher concentration of hydrogen ions. Basic Solutions: pH >7 The more basic a solution, the higher the pH value. This means a higher concentration of hydroxide ions. Neutral Solutions: pH = 7 A solution that is neither acidic nor basic There is the same number of hydrogen ions as hydroxide ions.

14. One More Thing About the pH Scale… The concentration of H + ions associated with a value on the pH scale differs from the next value by a power of 10. This means that a solution with a pH of 5 has a concentration of hydrogen ions that is 10 (10 1 )times greater than a solution with a pH of 6. A solution with a pH of 2 has a concentration of hydrogen ions that is 100 (10 2 ) times greater than a solution with a pH of 4.

15. One More Thing About the pH Scale… The concentration of H + ions associated with a value on the pH scale differs from the next value by a power of 10. This means that a solution with a pH of 5 has a concentration of hydrogen ions that is 10 (10 1 )times greater than a solution with a pH of 6. A solution with a pH of 2 has a concentration of hydrogen ions that is 100 (10 2 ) times greater than a solution with a pH of 4. How much greater is the concentration of hydrogen ions in a solution with a pH of 3 compared to a solution with a pH of 7?

17. Measuring pH pH paper – a universal acid-base indicator, turns different colors at particular pH values Compare the resulting color against a chart to determine pH value pH meter – a device with used to probe the electrical properties of a solution to determine pH The most accurate method!