Presentation on theme: "213 PHC. Introduction Chemicals make up everything we use or consume. The knowledge of the chemical composition of a substance is important in our daily."— Presentation transcript:
Chemicals make up everything we use or consume. The knowledge of the chemical composition of a substance is important in our daily lives. Analytical chemistry plays an important role in all aspects (agricultural, clinical, environmental, forensic, manufacturing, and pharmaceutical). Analytical chemistry consists of qualitative and quantitative analysis. Qualitative analysis tells us what chemicals are present. Quantitative analysis tells us how much
By the end of this lecture the student should be able to: Describe the common acid-base theories. Classify substances as acids and bases. Understand acid-base equilibria in water.
Acid-Base Theories Arrhenius Theory: Acid HA + H 2 O H 3 O + + A - Weak Base B + H 2 O BH + + OH - Strong Base M(OH) n M n+ + nOH -
Bronsted-Lowry Theory: acid = H + + base Acid donate a proton Base accept a proton
Lewis Theory: Electronic theory of acids and bases. Acid accept electron pair Base donate electron pair AlCl 3 + :OR 2 Cl 3 Al:OR 2
Acid-Base Equilibria in Water When an asid or base is dissolved in water, it will dissociate, or ionize. A strong acid or base is completely dissociated. A weak acid or base is partially dissociated.
e.g. HOAc H + + OAc - Ka = [H + ] [OAc - ] / [HOAc]
H 2 O H + + OH - K w = [H + ] [OH - ] K w = 1 x 10 -14