1. Acids and Bases Chapter 2

4. Acids taste sour, are corrosive to metals, change litmus (a dye extracted from lichens) red, and become less acidic when mixed with bases. Acids taste sour, are corrosive to metals, change litmus (a dye extracted from lichens) red, and become less acidic when mixed with bases.bases Bases feel slippery, change litmus blue, and become less basic when mixed with acids. Bases feel slippery, change litmus blue, and become less basic when mixed with acids.acids

6. Explanation: Starting in 1983, instead of the solid copper, American pennies are made of zinc coated with a think layer of copper. Explanation: Starting in 1983, instead of the solid copper, American pennies are made of zinc coated with a think layer of copper. The zinc metal inside reacts with dilute sulfuric acid to form zinc sulfate and hydrogen (bubbles). The zinc metal inside reacts with dilute sulfuric acid to form zinc sulfate and hydrogen (bubbles). Copper does not react with dilute acids. After the zinc is dissolved (reacted), only the copper shell of the penny is left. Copper does not react with dilute acids. After the zinc is dissolved (reacted), only the copper shell of the penny is left.

7. ACIDS/ BASES Acids – ex. HCl… Acids – ex. HCl… has H+ ions has H+ ions Reads 0-6 on Ph scale because more H+ ions Reads 0-6 on Ph scale because more H+ ions Neutral : pH 7 equal amounts of OH and H Neutral : pH 7 equal amounts of OH and H Bases: ex. NaOH…. Bases: ex. NaOH…. has OH- ions has OH- ions Reads 8-14 on pH scale… more OH – ions Reads 8-14 on pH scale… more OH – ions

8. pH scale Used to measure strength or weakness of acids and bases Used to measure strength or weakness of acids and bases Closer to 7 ? Weak acid or base Closer to 7 ? Weak acid or base Closer to 1? Strong Acid Closer to 1? Strong Acid Closer to 14? Strong Base Closer to 14? Strong Base

10. pH information Ph of 2 is 10x stronger than pH of 3… Ph of 2 is 10x stronger than pH of 3… What about 4 or 5? What about 4 or 5? pH of body 6.5-7.5 pH of body 6.5-7.5 Urine Urine Blood Blood CO2 CO2 Controlling pH is homeostasis Controlling pH is homeostasis pH- “potential of hydrogen” pH- “potential of hydrogen”

11. Mini-Lab Carbon dioxide is a base Carbon dioxide is a base When it comes into contact with water it becomes carbonic acid which is an acid When it comes into contact with water it becomes carbonic acid which is an acid Bromothymol blue is an indicator– it turns yellow.green in the presence of an acid and blue in the presence of a base Bromothymol blue is an indicator– it turns yellow.green in the presence of an acid and blue in the presence of a base

12. NameAcid Color pH Range of Color Change Base Color Methyl violetYellow0.0 - 1.6Blue Thymol blueRed1.2 - 2.8Yellow Methyl orangeRed3.2 - 4.4Yellow Bromocresol green Yellow3.8 - 5.4Blue Methyl redRed4.8 - 6.0Yellow LitmusRed5.0 - 8.0Blue Bromothymol blueYellow6.0 - 7.6Blue Thymol blueYellow8.0 - 9.6Blue PhenolphthaleinColorless8.2 - 10.0Pink ThymolphthaleinColorless9.4 - 10.6Blue Alizarin yellow RYellow10.1 - 12.0Red

14. ACID /BASES/ NEUTRAL /BUFFER Buffer is a substances that prevents sharp increase or declines in pH. Buffer is a substances that prevents sharp increase or declines in pH. You have buffers in your body and in your blood stream, that help keep your body at a fairly neutral pH. You have buffers in your body and in your blood stream, that help keep your body at a fairly neutral pH. When using the pH meter we need to insert the probe in buffer solution, in between samples…… why? When using the pH meter we need to insert the probe in buffer solution, in between samples…… why?

16. More acid base info … Acidic solutions have a pH between 1 and 6.9 === your stomach contains HCl it is pH2. Acidic solutions have a pH between 1 and 6.9 === your stomach contains HCl it is pH2. Alkaline (Basic) solutions have a pH between 7.1 and 14. === your small intestine is pH 9. Alkaline (Basic) solutions have a pH between 7.1 and 14. === your small intestine is pH 9. Neutral solutions are neither acidic nor alkaline so their pH is 7. Neutral solutions are neither acidic nor alkaline so their pH is 7.