Descaling Coffee Machines

Topics: Acetic acid, Oxygen, Vinegar Pages: 2 (546 words) Published: May 13, 2014
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Citric acid: Citric acid is a weak organic acid with the formula C6H8O7. Citric acid is a natural preservative/conservative and is also used to add an acidic or sour taste to foods and soft drinks. In biochemistry, the conjugate base of citric acid, citrate, is important as an intermediate in the citric acid cycle, which occurs in the metabolism of all aerobic organisms. Citric acid is a commodity chemical, and more than a million tonnes are produced every year by fermentation. It is used mainly as an acidifier, as a flavouring, and as a chelating agent. At room temperature, citric acid is a white crystalline powder. It can exist either in an anhydrous (water-free) form or as a monohydrate. The anhydrous form crystallizes from hot water, while the monohydrate forms when citric acid is crystallized from cold water. The monohydrate can be converted to the anhydrous form by heating above 78 °C. Citric acid also dissolves in absolute (anhydrous) ethanol (76 parts of citric acid per 100 parts of ethanol) at 15 °C. In chemical structure, citric acid shares the properties of other carboxylic acids. When heated above 175 °C, it decomposes through the loss of carbon dioxide and water. Citric acid is a slightly stronger acid than typical carboxylic acids because the anion can be stabilized by intermolecular hydrogen-bonding from other protic groups on citric acid. Citric acid has a sour taste.

Ethanoic acid also known as acetic acid and also commonly known as vinegar: is an organic compound with the chemical formula CH3COOH. It is a colourless liquid that when undiluted is also called glacial acetic acid. Acetic acid is the main component of vinegar (apart from water; vinegar is roughly 8% acetic acid by volume), and has a distinctive sour taste and pungent smell. Besides its production as household vinegar, it is mainly produced as a precursor to polyvinylacetate and cellulose acetate. Although it is classified as a weak acid, concentrated acetic acid is...
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