alkali:/
In chemistry, an alkali is a basic, ionic salt of an alkali metal or alkaline earth metal element. Some authors also define an alkali as a base that dissolves in water. A solution of a soluble base has a pH greater than 7. The adjective alkaline is commonly used in English as a synonym for base, especially for soluble bases. This broad use of the term is likely to have come about because alkalis were the first bases known to obey the Arrhenius definition of a base and are still among the more common basic.


Alkalis are all Arrhenius bases, which form hydroxide ions (OH^-) when dissolved in water. Common   properties of alkaline aqueous solutions include:Moderately concentrated solutions (over 10⁻³ M) have a pH of 7.1 or greater. This means that they will turn phenolphthalein from colorless to pink.

• Concentrated solutions are caustic (causing chemical burns).
• Alkaline solutions are slippery or soapy to the touch, due to the saponification of the fatty substances on the surface of the skin.
• Alkalis are normally water soluble, although some like barium carbonate are only soluble when reacting with an acidic aqueous solution.

Moderately concentrated solutions (over 10⁻³ M) have a pH of 7.1 or greater. This means that they will turn phenolphthalein from colorless to pink.

Key facts:/
1. Acids have a pH of less than 7
2. Alkalis have a pH of greater than 7
3. Alkalis have a soapy feel to the touch
4. Acids react with alkalis
5. Acids turn litmus paper red
6. Hydrocholic acid has the chemical formula HCl
7. Sodium hydroxide, an alkali, has the chemical formula NaOH
8. Concentrated acids can dissolve coins
9. Lemons contain citric acid
10. Bleach usually contains Sodium Hydroxide.
acids:/

An acid (from the Latin acidus/acēre meaning sour^[1]) is a substance which reacts with a base. Commonly, acids can be identified as tasting sour, reacting with metals such as calcium, and bases like sodium carbonate. Aqueous acids have a pH under 7, with acidity increasing the lower the pH. Chemicals or substances having the property of an acid are said to be acidic.
Common examples of acids include acetic acid (in vinegar), sulfuric acid (used in car batteries), and tartaric acid (used in baking). As these three examples show, acids can be solutions, liquids, or solids. Gases such as hydrogen chloride can be acids as well. Strong acids and some concentrated weak acids are corrosive, but there are exceptions such as carboranes and boric acid.