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Ethanoic Acid Lab Report

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Investigating the relationship between temperature and equilibrium constant in weak acids

Topic/Purpose The topic of the investigation is equilibria of weak acids, using ethanoic acid. The purpose of the investigation is to determine the relationship between temperature and the equilibrium/dissociation constant of weak acids, by calculating the K_a value of ethanoic acid at various temperatures.
Aim
The aim of the investigation is to determine whether the relationship between temperature and the equilibrium constant is linear or exponential by measuring the pH of a weak acid at various temperatures ranging from 20 ˚C to 80 ˚C. This will be achieved by deducing the K_a values for the acid, and plotting them on a graph against temperature. …show more content…

Weak acids do not fully dissociate in a solution, releasing only some of their hydrogen atoms, and an equilibrium is formed when they react. Ethanoic acid is an organic compound and has a pH of 2.9, is a component of vinegar, and has anti-bacterial properties. However, it also has negative properties since it can inhibit carbohydrate metabolism, leading to the demise of the organism. Figure 1. Molecular structure of ethanoic acid pH is a measure of how acidic or alkaline a solution is, and it is measured using a scale ranging from 0 to 14, 0-6 being acidic, 8-14 basic and 7 neutral. However, if a solution is a very strong alkali or very strong acid, its pH value can be outside of the scale. pH is also a measure of hydrogen ions (H^+) in the solution. According to the Arrhenius definition an acid forms hydrogen ions in an aqueous solution. However, the Bronsted-Lowry theory suggests that an acid is a substance which can act as proton donor. Finally, the Lewis theory states that an acid is a lone pair of electrons acceptor (to form a dative covalent bond). Acids also have the ability to turn blue litmus red and form salts when they react with bases and certain metals. Weak acids normally have pH values ranging from 2 to

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