Definition Of Formal Theory

Formal Lab Theory

a. The overall definition of an acid is a substance that is dissolved in water, and therefore said to be aqueous, and well as contains a hydrogen ion as a part of its chemical structure. The overall definition of a base is a substance that is dissolved in water to be aqueous, and contains a hydroxide ion (OH-) as its anion. More specifically, three culminating definitions of acids and bases can be used to explain an acid’s and base’s chemical structure, behavior, and properties. These three definitions are known by their founder(s): The Arrhenius Definition, The Brønsted-Lowry Definition, and The Lewis Definition. The Arrhenius Definition was first developed and integrated by the Swedish chemist Svante Arrhenius. Arrhenius’s definition of an acid proposed it to be a substance that dissociates in water to produce hydrogen ions (H+). Examples of such Arrhenius acids include hydrochloric acid (HCl), nitric acid (HNO3), and phosphoric acid (H3PO4). As it can be easily seen, when these acids are placed in water, the acid dissociates to yield hydrogen ions, and hence defines them as Arrhenius acids. This also allows these Arrhenius acids to be electrolytes because free-moving particles exist in the water, in which electricity can be conducted. The Arrhenius definition of a base is a substance that dissociates in water to produce hydroxide ions (OH-). Examples of such substances include sodium hydroxide (NaOH), potassium hydroxide (KOH), and calcium hydroxide [Ca(OH)2]. Evidently, these substances separate into their respective cations and the hydroxide ions. Similarly, bases are electrolytes according to the Arrhenius definition because they form free-moving particles when in a water solution. Although the Arrhenius...

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...ion in the substance. For example to calculate the pH of 0.0025 M HCl with a hydronium ion concentration of 0.00.25 M:

pH = -log [H3O+] pH = -log[0.0025] pH = 2.60

In the reverse order, by knowing the pH value. This can be be done by using an antilog in the calculation:

2.60 = -log [H3O+ ]

[H3O+ ] = antilog (-pH)

[H3O+ ] = 10-2.60

[H3O+ ] = 0.0025 M

From a laboratory perspective, the pH of a substance could be calculated by performing a titration to find the molar concentration of the substance itself. Then, this data can be substituted into the Acid Dissociation constant expression to solve for the unknown concentration of hydronium ions in the solution. As soon as this is computed via mathematical calculations, the hydronium ion concentration can then be inserted into the expression used to calculate the pH of the substance.

d.