1. Mrs. Howland Chemistry 10 Rev. April 2016

2. Learners will be able to… Identify acids and bases by chemical formula Compare and contrast acids and bases Define Arrhenius acids and bases Define Br Ø nsted Lowry acid, base, conjugate acid, and conjugate base Determine pH for common household items using universal indicator Determine pH and pOH from concentrations of H + and OH - Determine concentrations of H + and OH - given the pH and/or pOH Perform titration using indicator to identify the endpoint Calculate the molarity or volume of an acid or base for a neutralization reaction

3. Acids and bases are commonly found in many foods and household products VIDEO: https://goo.gl/PMjZ1rhttps://goo.gl/PMjZ1r

4. One way to define acids and bases are by their PROPERTIES Some acids also react with metals to produce hydrogen gas!

5. Swedish chemist Svente Arrhenius gave early definition of acids and bases Arrhenius ACIDS = Substances that dissociate in water to produce H + ions Arrhenius BASES = Substances that dissociate in water to produce OH - ions

6. A hydrogen ion (H + ) is a hydrogen atom that has LOST its electron It has only 1 proton, giving a +1 charge “No electrons?!?! Weird …”

7. It wasn’t discovered until after Arrhenius’s time that H + does not exist freely in water H + ions bond with water molecules to form H 3 O + (called the hydronium ion) BUT … H 3 O + is often abbreviated to H + So they mean the same thing!

8. Some reactions occur both forward and in reverse When RATE of the forward and reverse reactions is equal, there is said to be equilibrium Does NOT mean that the concentration/amounts of products and reactants are equal! ONLY the rates of reaction. Equilibrium is represented by double arrows

9. Two scientists, Johannes Br Ø nsted and Thomas Lowry, made adjustments to Arrhenius theory to account for equilibrium Br Ø nsted-Lowry ACID = Hydrogen-containing substance that donates a proton Br Ø nsted-Lowry BASE = Any substance that accepts a proton

10. Examine the following. Which is a Br Ø nsted- Lowry acid? Br Ø nsted-Lowry base?

11. In the FORWARD reaction, HCl is the BL acid and H 2 O is the BL base In the REVERSE reaction, H 3 O + is the BL acid and Cl - is the BL base

12. OCCUR IN PAIRS due to equilibrium: Base with conjugate acid Acid with conjugate base

13. Conjugate acid = Substance that accepts a hydrogen and proton Conjugate base = Substance that remains after hydrogen and proton are removed (usually the anion!)

14. Identify: Bronsted-Lowry acid Bronsted-Lowry base Conjugate acid Conjugate base 1. 2.

15. Salts also dissolve in water to form aqueous solutions How are salts different? They don’t produce H + or OH - ions They produce ions other than H + and OH -

16. https://www.youtube.com/watch?v=DupXDD87 oHc

18. pH is the measurement of the strength of an acid or a base POWER of HYDROGEN! portenz means strength  ‘p’ H is the symbol for Hydrogen p + H = pH

19. pH scale runs from 0-14 pH 0-7 is ACIDIC pH 7 is NEUTRAL pH 7-14 is BASIC (remember that alkaline means ‘basic’)

20. Universal indicator turns different colors depending on pH Red and blue litmus paper are pH indicators that test ONLY for acids or bases (not neutral substances!)

21. As you move along the pH scale, pH 7 (NEUTRAL) is the central point. Moving away from pH 7, substances become more acidic or more basic

22. POWER of HYDROGEN!(CON CENTRATION of H+ ions)

23. The pH scale is based on a logarithm to the base 10 which means that each step along the pH scale represents a change in the strength of the acid or base by 10x.

24. pH of 5 (black coffee) is ten times (10x) stronger than pH of 6 (urine/saliva) This means that pH of 5 has 10x more hydogen ions than pH of 6

25. Which is a stronger acid, acid rain or soda? Which is a weaker base, ammonia or bleach?

26. CONCENTRATION of H+ ions (remember they are usually present as H 3 O + ions!) CONCENTRATION is measured by MOLARITY (moles/L) The formula for calculating pH is: pH = – log 10 [H 3 O + ]

27. The formula for calculating pH is: pH = – log 10 [H 3 O + ] The square brackets [ ] represent CONCENTRATION This formula is for the inverse of the log10 of the concentration of H 3 O+ Find the log button on your calculator!

28. Bases are approached by calculating the pOH the concentration of OH - ions The formula for pOH is: pOH = – log 10 [OH – ]

29. Check it out: pH + pOH = 14

30. ACIDS form H + ions (H 3 O + ) in aqueous solution BASES form OH - ions in solution If the amount of H + is known, the amount of OH- can be known And vice-versa!

31. The formula for pH is: pH = – log 10 [H 3 O + ] The formula for pOH is: pOH = – log 10 [OH – ] Now, we just need to figure out how to use our calculators for these formulas!

32. What is the pH of a solution with a hydrogen concentration of 4.2 x 10-10 M? ENTER: 4.2 (EE button) -10 Log button Answer: -9.38  Make it positive: pH = 9.38

33. The formula for H+ concentration is: [H 3 O + ] = antilog(-pH) The formula for OH concentration is: [OH – ] = antilog(-pOH) Now, we just need to figure out how to use our calculators for these formulas!

34. What is the hydrogen ion concentration for a solution with a pH of 6.35? ENTER: 6.35 then make it negative (+/- button) 2 nd key or INV key, then log button Answer: 4.5 x 10-7 M = [H + ]

35. What is the pH of a solution with a [H 3 O + ] of 7.4 x 10 -4 ? ANSWER: pH = - log[H 3 O + ] = -log (7.4 x 10-4) = 3.13, which we round to 3.1 the pH is 3.1

36. What is the pH of a 0.01M solution of HCl? Remember ‘M’ is concentration, so you would plug the value 0.01M into the formula like this: pH = antilog [-H 3 O + ] = -log (0.01) = 2 the pH is 2

37. REMEMBER: pH + pOH = 14 The formula for H+ concentration: [H 3 O + ] = antilog(-pH) The formula for OH concentration: [OH – ] = antilog(-pOH) The formula for pH: pH = – log 10 [H 3 O + ] The formula for pOH: pOH = – log 10 [OH – ]