Video Point Experiment 3 – Conductometric Titration Of Strong Acid And Strong Base r25k

Video point experiment 3 – Conductometric titration of strong acid and strong base 1. Apparatus needed to conduct experiment that determine the strength of given strong acid solution by titration against standard alkali solution conductometrically are conductivity meter, pipette, beaker and burette. 2. Titration end point cannot be determined by chemical indicator because:  No suitable indicator  No stable end point  Solution is too dilute  Solution is too turbid  Solution is brightly colored 3. In acid base titration, conductometric titration can measure the change in conductivity of solution to find end point. 4. Electrolytic solution follows the Ohm’s Law, V=IR, where V is voltage, I is current and R is resistance. Current due to migration of ions is proportional to the voltage. 5. Presence of ions increases the conductivity of water, Conductance depends on concentration, type of ions, temperature and construction of device. 6. HCl is a strong acid. The conductivity is high due to H+ and Cl-. When strong base, NaOH is added, H+ are slowly consumed by the OHions and water, H2O is formed. H++NaOH → Na++ H2O 7. Highly conducting H+ are effectively replaced by poorly conducting Na+ so the conductivity decreases. The process continues until all H+ ions are neutralized. Na++Cl- → NaCl 8. Overall process NaOH+HCl → NaCl+ H2O This is called endpoint. Further NaOH addition will increase the conductance. Hence, the conductometric curve has a minimum at equivalence point. 9. Position of endpoint is formed at the intersection of the graph. Its x coordinate tells us volume which is required. 10. For weak acid and strong base, base should be titrated with acid. For strong acid and weak base, acid should be titrated with base.