Understandings● The expression for the dissociation constant of a weak acid (Ka) and a weak base (Kb).
● For a conjugate acid–base pair, Ka Å~ Kb = Kw. Guidance ● The value Kw depends on the temperature. ● Only examples involving the transfer of one proton will be assessed. ● Calculations of pH at temperatures other than 298 K can be assessed. ● The relationship between Ka and pKa is pKa = –logKa and between Kb and pKb is pKb = –logKb. 
Applications and skills● Solution of problems involving [H+(aq)], [OH–(aq)], pH, pOH, Ka, pKa, Kb, and pKb.
Guidance ● Students should state when approximations are used in equilibrium calculations. ● The use of quadratic equations will not be assessed. ● Discussion of the relative strengths of acids and bases using values of Ka, pKa, Kb, and pKb. Guidance The calculation of pH in buffer solutions will only be assessed in options B.7 and D.4. 
Inquiry questions

Calculations involving Acids and Bases
Explanation how pH and Kw are linked
Follow the exercise that explains how you can determine Kw
Explanation on Acid Strength
Follow the exercise that explains how you can determine pH

Test yourself
1. Question: Determine the pH for each of the given solutions.
a. 0.150 M HNO3
b. 0.150 M CH3COOH, Ka = 1.8 × 105
c. 0.150 M CHOOH, Ka = 3.5 × 104
a. 0.150 M HNO3
b. 0.150 M CH3COOH, Ka = 1.8 × 105
c. 0.150 M CHOOH, Ka = 3.5 × 104
acid deposition

Oxidation and REduction

Introduction to oxidation and REductionThis video is introducing the basics of oxidation and reduction as well as explains what oxidation numbers are and how they are useful in redox reactions.


Redox Titration 