Acid

From CreationWiki, the encyclopedia of creation science

The word "acid" comes from the Latin acidus meaning "sour," but in chemistry the term acid has a more specific meaning, which is most commonly accepted to be a chemical substance that acts as a proton donor (H⁺).

1 Common acid reactions
2 Properties
3 pH scale
4 Definitions
5 Gallery
6 References
7 See Also

Common acid reactions

acidic lemon pH of 4

Acids are generally sour in taste. Strong or concentrated acids often produce a stinging feeling on mucous membranes. React to indicators as follows: turn blue litmus and methyl orange red, do not change the color of phenolphthalein

Will react with metals to produce a metal salt and hydrogen
Will react with metal carbonates to produce water, CO₂ and a salt
Will react with a base to produce a salt and water
Will react with a metal oxide to produce water and a salt
Will conduct electricity, depending on the degree of dissociation
Will produce solvonium ions, such as hydronium (H₃O+) ions in water
Will denature proteins.[1]

Properties

Acids have many properties that stand out. Some that you might be familiar to is in food and houshold cleaning products. It gives your food the sour taste and cleaning products the power to kill germs and erode stains. Acids react with compounds containing hydroxide ions to form water and a salt. There are several main types of acids: Citric, Malic, Lactid, Acidic, succinic, and Tartaric. Tararic and malic acid are found naturaly in grape juices. Citric is a less common acid found in that. Acidic and succsinic are found in wines/must along with Lactid, and Malic. Tartaric Acid is the main acid added to increase the acidity or lower the pH of grape juice or wine. Citric Acid is often added for acidification as it is claimed to taste fruitier. [2]

pH scale

3-d model

You may have heard of something called the pH scale. This is what determines the hydrogen-ion acidity, of a solution; it is the negative logarithm of the hydrogen-ion concentration of a solution. In other words, any PH number higher than 7 is basic, and anything lower that 7 is acidic. Most PH values are whole numbers. [3]

Definitions

There are four definitions of acids:

The Arrhenius."This acid is a substance that increases the concentration of hydrogen ions (H+), which are carried as hydronium ions (H3O+) when dissolved in water, while bases are substances that increase the concentration of hydroxide ions (OH-). This definition limits acids and bases to substances that can dissolve in water."

The Brønsted-Lowry."This acid is a proton (hydrogen nucleus) donor and a base is a proton acceptor. The acid is said to be dissociated after the proton is donated. An acid and the corresponding base are referred to as conjugate acid-base pairs. Brønsted and Lowry independently formulated this definition, which includes water-insoluble substances not in the Arrhenius definition."

The Lewis."This acid is an electron-pair acceptor and a base is an electron-pair donor. Lewis acids include substances with no transferable protons."

And the solvent-system."An acid is a substance that, when dissolved in an autodissociating solvent, increases the concentration of the solvonium cations, such as H3O+ in water, NH4+ in liquid ammonia, NO+ in liquid N2O4, SbCl2+ in SbCl3, etc." [4]