Acids and Bases

OBJECTIVE: To study the reaction of typical acids (dilute hydrochloric acid) with metals, metal oxides, carbonates and bases. The following materials were used to complete this experiment: the dropper bottle contained 0.1 M hydrochloric acid or lime water (calcium hydroxide) and sodium hydroxide solution. Next metal dropper bottle bromothymol blue indicator Small sample: zinc, copper, magnesium and iron oxide copper (II) powder magnesium oxide marble chip (calcium carbonate) sodium carbonate 12 test tube and test tube holder cork wax cone and matching PROC

For acid catalysts and basic catalysts, the chemical reaction is catalyzed by acid or base. The acid is a proton donor and the base is a proton acceptor, called Bronsted-Lowry acid and base, respectively. Typical reactions catalyzed by proton transfer are esterification reaction and aldol reaction. In these reactions, the conjugate acid of the carbonyl group is a better electrophile than the neutral carbonyl. The catalysis of acids or bases can occur in two different ways: specific catalysis and general catalysis. Many enzymes pass acid catalysis

In the Bronsted - Lowry acid - base theory, the acid - base reaction involves the transfer of a proton (H +) from one species (acid) to another species (acid). Once the protons are removed from the acid, the resulting material is called the conjugate base of the acid. When a proton is accepted by a base, the resulting material is called a base conjugate acid. In other words, the acid acts as a proton donor and the base acts as a proton acceptor. According to the following formula: Since the reaction is possible, the acid / base and the conjugate base / acid are always in equilibrium. The equilibrium is determined by the dissociation constants (Ka and Kb) of the acids and bases of the substances involved. A special case of acid-base reaction is neutralization, where acid and base form exactly the same amount of neutral salt.

Acid-base titration is used to determine an unknown concentration of acid or base by neutralizing an acid or base with a known concentration of acid or base. The stoichiometry of the reaction can be used to determine the unknown concentration. It makes use of knowledge of the neutralization reactions occurring between acids and bases, and how acid and base react when their formulation is known. Strong acid titration with strong acid was carried out using phenolphthalein indicator. Phenolphthalein was chosen because it changes color in the pH range from 8.3 to 10. It appears pink in alkaline solution and becomes transparent in acidic solution. In the case of strong acid and strong base titration, this pH shift occurs in only a small part of the actual neutralizing droplet, as the strength of the base is high.