1. Acids, Bases & pH

2. WATER Before understanding Acids and Bases, you must understand water. 1. It is a polar covalent molecule. Like a magnet. ++ - -

3. WATER 1. It is a polar covalent molecule. WHY??? Oxygen pulls on the electrons more than Hydrogen does. ++ - -

4. WATER Because water is POLAR (negative side and positive side), what types of compounds will it DISSOLVE easily? Covalent or Ionic? ++ - -

5. Ionic Compounds: Acids Ionic compounds that break apart (dissolve) in water to form a hydronium ion, H 3 O + (hydrogen ion, H+). The more H + ions released in water = STRONGER ACID Ionic compounds that break apart (dissolve) in water to form a hydronium ion, H 3 O + (hydrogen ion, H+). The more H + ions released in water = STRONGER ACID Or written as HCl  H 3 O + + Cl -

6. AcidsAcids When HCl is put in water, a Hydronium ion, H 3 O + (hydrogen ion, H+) is formed. When HCl is put in water, a Hydronium ion, H 3 O + (hydrogen ion, H+) is formed. Or written as HCl  H 3 O + + Cl -

7. Acids, Bases and pH Why do we need to know? Acids, Bases and pH Why do we need to know? The pH of a substance determines its physical and chemical properties. The pH of a substance determines its physical and chemical properties.

8. Characteristics of Acids 1.Taste Sour 2.React Strongly with Metals and Carbonates (in soil and rocks) 3.Can burn your skin 4.Conduct electricity in water 5.Turn indicator red Characteristics of Acids 1.Taste Sour 2.React Strongly with Metals and Carbonates (in soil and rocks) 3.Can burn your skin 4.Conduct electricity in water 5.Turn indicator red AcidsAcids Examples of Acids 1.Vinegar 2.Citrus fruits 3.Stomach Acid (HCl) Examples of Acids 1.Vinegar 2.Citrus fruits 3.Stomach Acid (HCl)

9. Ionic Compounds: Bases Ionic compounds that break apart (dissolve) in water to form a negatively charged hydroxide ion (OH-). More OH - ions released in water = STRONGER BASE Ionic compounds that break apart (dissolve) in water to form a negatively charged hydroxide ion (OH-). More OH - ions released in water = STRONGER BASE NaOH  Na + + OH -

10. Acids, Bases and pH Why do we need to know? Acids, Bases and pH Why do we need to know? The pH of a substance determines its physical and chemical properties. The pH of a substance determines its physical and chemical properties.

11. BasesBases Characteristics of Bases 1.Taste bitter 2.Feel Slippery 3.Can burn your Skin 4.Turn indicator blue 5.Conduct electricity in water Characteristics of Bases 1.Taste bitter 2.Feel Slippery 3.Can burn your Skin 4.Turn indicator blue 5.Conduct electricity in water Examples of Bases 1. Lye (Sodium Hydroxide) 2. Ammonia 3. Bleach Examples of Bases 1. Lye (Sodium Hydroxide) 2. Ammonia 3. Bleach

12. pH What does it mean? pH What does it mean? pH – potential of Hydrogen – the ability to release H+ The more H+ released in water, the HIGHER the pH. Which one below releases more H+? 1.HBr  H 3 O + + Br - or written as HBr  H + + Br - 2.KOH  K + + OH - pH – potential of Hydrogen – the ability to release H+ The more H+ released in water, the HIGHER the pH. Which one below releases more H+? 1.HBr  H 3 O + + Br - or written as HBr  H + + Br - 2.KOH  K + + OH -

13. pHpH Which has a greater ability to release H+ in water? Which has HIGHER pH? HBr  H + + Br - YES! And therefore this shows a higher pH (potential of Hydrogen) KOH  K + + OH - NO! And therefore this shows a lower pH (potential of Hydrogen) Which has a greater ability to release H+ in water? Which has HIGHER pH? HBr  H+ + Br- YES! And therefore this shows a higher pH (potential of Hydrogen) KOH  K+ + OH- NO! And therefore this shows a lower pH (potential of Hydrogen)

14. pHpH COMPARE: WHAT ARE THEIR pH VALUES????? HBr  H + + Br - About 1 to 2 KOH  K + + OH - About 13 to 14 COMPARE: WHAT ARE THEIR pH VALUES????? HBr  H+ + Br- About 1 to 2 KOH  K+ + OH- About 13 to 14

15. pHpH pH – potential of Hydrogen – the ability to release H+ WHAT ABOUT NEUTRAL WATER? H 2 O  H + + OH - What is the pH for this? WHAT ABOUT NEUTRAL WATER? H 2 O  H + + OH - What is the pH for this?

16. pHpH pH – potential of Hydrogen – the ability to release H+ NEUTRAL WATER: H 2 O  H + + OH - NEUTRAL = pH 7 HOW DOES THIS HAPPEN? NEUTRAL WATER: H 2 O  H + + OH - NEUTRAL = pH 7 HOW DOES THIS HAPPEN?

17. pHpH H 2 O  H 3 O + + OH - H 2 O  H 3 O + + OH - pH 7 Dissociation – the breaking apart of water into ions. H 3 O + = OH - H 2 O  H 3 O + + OH - H 2 O  H 3 O + + OH - pH 7 Dissociation – the breaking apart of water into ions. H 3 O + = OH -

18. The pH Scale Tells the concentration of (how many) hydrogen (H + ) ions in solution. Hydrogen Ion Concentration in Moles/Liter at 25° C pHH+ conc. 01.0 10.1 20.01 30.001 40.0001 50.00001 60.000001 70.0000001 80.00000001 90.000000001 100.0000000001 110.00000000001 120.000000000001 130.0000000000001 140.00000000000001

19. The pH Scale Tells the concentration of (or how many) hydrogen (H + ) ions in a water solution. Each move up the scale is a jump of 10 TIMES.

20. HOW MANY TIMES? How many times stronger is pH 3, than pH 4? pH3 is 10 times stronger than pH4 Or another way, 1 jump up the scale equals 10 times more H+ ions! How many times stronger is pH 5, than pH 8? 3 jumps up the scale? 10 x 10 x 10 1,000 times more H+ ions! 1,000 times stronger! How about pH 1 than pH 7? 6 jumps 10 x 10 x 10 x 10 x 10 x 10 1,000,000 times! 1,000,000 times MORE H+ ions!

21. The 0 – 14 pH scale was created to show amount of H+ ions in a water solution. pH of a neutral solution = 7 H + concentration = OH - concentration Acidic pH values: 0 – 6, MAXIMUM = 0 Basic pH values: 8 – 14, MAXIMUM = 14 The pH Scale

22. IndicatorIndicator IndicatorIndicator Indicator – changes color as the pH changes, and thus tells us the pH of a solution. Indicator – changes color as the pH changes, and thus tells us the pH of a solution.

24. NEUTRALIZATION What happens when an ACID is added to a BASE ???? They react to form a salt and water Hydrochloric Acid + Sodium Hydroxide  Water + Table Salt HCl + NaOH  H 2 O + NaCl

25. Acids and Bases and Neutralization One of the most important aspects of a living system is the amount of acidity or alkalinity

26. NEUTRALIZATION NEUTRALIZATION: Why do we need to know? NEUTRALIZATION NEUTRALIZATION: Why do we need to know? Control of pH is very important Control is accomplished with buffers

27. Buffers neutralize small amounts of either an acid or base.pH Why do we need to know?pH

28. pH pH Alkalinity – the ability of a stream to neutralize acids.

29. STOP HERE