Huong Le AP Chemistry Period ⅘ May 11, 2017 Lab Experiment 1: Acid- Base Titration
Final Laboratory Experiments Date Conducted: May 4/5/8/9, 2017 I. ACID-BASE TITRATION A. Purpose: To determine experimentally the concentration of the unknown solutions used to titrate the standardized solutions prepared B. Hypothesis: Upon the addition of the acid into unknown bases, the solution will change color when the neutralization process has reached equivalent point. The color will change from pink to faint pink. C. Introduction: Titration is the slow addition of one solution of a known concentration (called a titrant) to a known volume of another solution of unknown concentration until the reaction reaches neutralization, which is often indicated by a color (chem.libretexts.org) Neutralization or neutralisation , is a chemical reaction in which an acid and a base react quantitatively with each other. In a reaction in water, neutralization results in there being no excess of hydrogen or hydroxide ions present in solution(wikipedia.com). In other words, the acid has neutralized the base and vice versa, making the new solution neutralized. The new solution then reaches equivalent point with no more acidic or basic characteristics. Excess in acid during neutralization reaction will turn phenolphthalein indicator to clear (the resulting solution is acidic) and excess in base during neutralization reaction will phenolphthalein indicator to faint pink(the resulting solution is basic), implicating that the neutralization reaction has passed equivalent point. In this experiment, using titration technique, we add standardized acid or base to neutralize the unknown acidic or basic solutions and determine the amount of acid or base needed for the neutralising reaction and the molarity of the unknown acid and base used. Upon passing equivalent point, the solution is expected to turn clear or colorless if the excess reagent is acid. Likewise, it is expected to turn faint pink if the excess reagent is base (Pearson: AP Chemistry Textbook,153)
D. Materials: - 150mL unknown base B-35/B-37 - 0.500M HCl solution (titrant) - 6.00M stock solution of HCl - Pipet pump - Ring stand - Stir bar - 50 mL buret - Stirrer - Buret clamp - 250mL Erlenmeyer flasks (3) - 250mL beaker (2) - 50mL graduated cylinder (1) - 250mL volumetric flask (1) - 100mL volumetric flask (1) - DI water - Phenolphthalein indicator E. Procedure: 1. Preparing 600mL of 0.500M acid titrant (HCl): 1. 50.00mL of 6.00M stock hydrochloric acid solution was obtained by the 50mL graduated cylinder 2. The acid was poured into a 250mL volumetric flask 3. Distilled water was added to the volumetric flask until the water level reached the calibration mark 4. Add water until a volume of 600mL is obtained 2. Titration of 0.500M acid with unknown base B-35 1. The buret was cleaned three times with DI Water.
- Fall '15
- Chemistry, ml, Sodium hydroxide, Erlenmeyer flask