standard soluti VII TITRATION a Concept analytical method

standard soluti VII. TITRATION a) Concept: analytical method used to determine the concentration of an unknown substance. Often an acid -base reaction. b) Equivalence point: point at which moles of H+ = moles of OH-; can use this fact (and the volumes involved) to calculate the molarity of the unknown (similar to dilution formula) i. The equivalence point can be determined by measuring the p. H at regular intervals and graphing the data or ii. Estimate the equivalence point by using an indicator unknown soluti

VII. TITRATION c) End Point: the point at which an indicator changes color i. This will be close to (but not exactly) the equivalence point. For example – phenolphthalein changes from colorless to pink at a p. H of about 8. If you are doing a strong acid/strong base titration, the equivalence point is at a p. H of 7. The difference is only a m. L or so, so it gives a very close approximation of the equivalence point

VII. TITRATION

VII. TITRATION d) Titration Calculation Formula Ma V a n a = M b V b n b M = molarity V = volume n = number of moles of OH- (for the base) or H+ (for the acid) -use the subscript a refers to the acid, b refers to the base

VII. TITRATION d. Titration Calculation i. example: 42. 5 m. L of 1. 3 M KOH are required to neutralize 50. 0 m. L of H 2 SO 4. Find the molarity of the sulfuric acid