1. Agenda 5-13-07 Do Now : 1.write the products of the reaction when the reactants given below undergoes double replacement reaction and balanced the equation: AB + CD -----> CB + AD HCl (aq) + Mg(OH) 2(s) ------> 2. Define the ff on page 525 - 528: buffer solution, standard solution, titration and equivalence point HW for tomorrow:  Check website under HW Objectives  Explain Neutralization Reaction in terms of acid base reaction  Solve problems involving neutralization in acid base reaction  To understand the general characteristic of buffered solution Upcoming: Test on Friday ( types of decays, nuclear stability, half-life, acid-base reaction) Don’t Forget to study!

3. What is the difference between Acid And base according to Arrhenius Theory? What’s the difference?

4. Acid produces H + in aqueous solution HCl (g) ------------> H + (aq) Cl - (aq)

5. Bases Produces OH - in aqueous Solution NaOH (s) -----> Na+ (aq) + OH- (aq)

7. What is the difference between Acid And base according to Bronsted- Lowry Theory? What’s the difference?

8. What is an indicator?

9. Indicator Substances that exhibit different colors in acidic and basic solutions It has a weak acid and a conjugate base

10. Explain neutralization reaction Objective #1

11. What happen when an acid reacts with a base? HCl + NaOH ---> HCl + NaOH ---> H 2 O + NaCl Neutralization Reaction  a type of double replacement reaction  A reaction between an acid and a base to form a neutral solution

12. Neutralization Reaction Acid and base properties combine to form water H + + OH - -------> H 2 O Note: water is one of the products of neutralization reaction

13. Exercise Write the products of the reaction below and balance the equation H 2 SO 4 + NH 4 OH ----> H 2 SO 4 + NH 4 OH ----> (NH 4 ) 2 SO 4 + H 2 O H 2 SO 4 + 2 NH 4 OH ----> (NH 4 ) 2 SO 4 + 2 H 2 O

14. Acid Base Titration Is a useful application of neutralization reaction A process of adding a solution of accurately known concentration, standard solution, ( titrant) to another solution of unknown concentration,( analyte until the chemical reaction between the two is complete ( the equivalence point) or end point Equivalence point is the point in titration where the indicator used undergoes a color change Note; indicator changes color at pH=7

15. How Does it Work? Load the titrant to OH- Base the burette and add the OH- titrant slowly to the analyte OH-OH- until exactly enough base OH- has been added to just react with all the analyte Acid with indicator H+ H+ H+ H+-

16. OH- OH-OH- OH- Has reached its equivalence point H+ H+

17. At the equivalence point, n Acid = n base, to get the molarity of the base or acid M = n = moles V L M acid = n acid, M base = n bas V acid V base n A = n B M A V A = M B V B

18. Ex: In a titration, It takes 6mL of 0.5MNaOH to neutralize 15mL of HCl. What is the concentration of HCl? NaOH + HCl -----> NaCl + H 2 O molar ratio ( 1:1) M A V A = M B V B M A = M B V B = (0.500M)(6mL) V A 15mL = 0.2M

19. Sample 2 A 25.0mL of sulfuric acid solution requires 32.58mL of.500M NaOH to neutralize it. What is the molarity of H 2 SO4? Solution: 1.Write the balance equation H 2 SO 4 + NaOH ---> H 2 SO 4 + NaOH ---> Na 2 SO 4 + H 2 O H 2 SO 4 + 2 NaOH ---> Na 2 SO4 + 2 H 2 O 2mole NaOH : 1 mole H 2 SO4 2.Determine the number of moles of NaOH M = n, n = MV n = (0.500moles) ( 0.03258L) = 0.01629 moles V L 3.Determine the molarity of H 2 SO 4 using nA = nB M = n, M = 0.01629moles NaOH x 1mole H 2 SO 4 V 0.025L 2mole NaOH M H 2 SO 4 = 0.3258M

20. Prob.#1 What volume of 1.5M NaOH is needed to react with 25mL of 4M HCl? Solution: 1.Write the balanced equation: HCl + NaOH ----> NaCl + H 2 O Ans V B = 67mL or 0.067L

21. Problem#2 In a titration, 50.0mL 0f 0.1204 M HCl requires 48.54mL NaOH solution for neutralization. What is the molarity of the NaOH solution?

22. Problem #3 What Volume of 0.150M HNO 3 solution is needed to neutralize 45.0mL of a 0.550M KOH solution? Given: MA = 0.150 MB = 0.550M VA = ? VB = 45mL Solution 1.

23. Problem#4 How many mL of 0.2056M NaOH is required to completely

24. How important is pH in living things?

25. pH plays an important role Most living organisms survive in a narrow pH Ex: human blood is maintained between 7.35 to 7.45 by buffering system

26. Buffers resist a change in pH even when a strong acid or base is added to it Contains --->weak acid and its conjugate base  weak base and its conjugate acid

27. Note: Buffers has a remarkable property of maintaining an almost constant pH even with the addition of a strong base or acid due to the presence of the weak acid that neutralizes any added base and also a weak base that neutralizes any added acid.

28. Ex: 1M CH3COOH and 1M NaCH 3 OO acetic Sodium acid acetate Added w/ a base CH 3 COOH + OH - ---> H 2 O + CH 3 COO - Added w/ an acid CH 3 COO + H 3 O + --> H 2 O + CH 3 COOH Note: acetate ion will neutralize any added acid -

29. What happens if the blood becomes basic or acidic? The bicarbonate-carbonic acid ( HCO3/H2CO3) buffer will buffer the blood.  If it becomes basic, the carbonic acid will neutralize the OH- ions  If it becomes acidic, the bicarbonate will neutralize the H 3 O+.