Indicators | Colour in acid | |||
Blue litmus | Red | |||
Methyl orange | Orange | |||
more...
Concentrated and Diluted Acid
The substance, which has hundred percent of acid is called concentrated acid. It completely dissolves in water and furnish ions.
The concentrated acid is also called strong acid. The acid, which has lower percent of acid is called diluted or weak acid. Dilute acid is not a pure form of acid, during the chemical reaction its performance is slower than the concentrated acid. It does not dissolve completely in water or furnish ions. In the following chemical reaction, carbon dioxide reacts with water and gives hydro carbonic acid. This is the weak and diluted acid.
Acids can be categorized into three main types, natural acids, mineral acid and organic acid. Natural acid is obtained from plants. The sources of citric acids are lemon and orange. Apple contains malic acid. Tomatoes are the big sources of oxalic acid. Milk is the source of lactic acid. Tea is the source of tannic acid. Vinegar is the source of acetic acid. Vitamins are the sources of amino acid. The acids prepared from the minerals are called mineral acid.
These are sulphuric acid , nitric acid and hydrochloric acid. Organic acid is obtained from plant and animal. The juice, which is obtained from plant and animal are mostly diluted acid because of the presence of water.
Some strong or concentrated acids are: Hydrochloric acid, sulphuric acid, nitric acid and phosphoric acid.
Some weak or diluted acids are: citric acid, acetic acid, carbonic acid, tartaric acid.
Every fruits contain acid. The acid found in fruits is called
(a) Strong acid
(b) Weak acid
(c) Mixed acid
(d) All of these
(e) None of these
Answer: (b)
The formation of add by the chemical reaction of carbon dioxide and water is called?
(a) Strong acid
(b) Dilute acid
(c) Basic acid
(d) Sulphuric acid
(e) None of these
Answer: (b)
Indicators
Indicators are used to indicate the nature of a substance. Chemical compounds have been categorized into three groups, that is, acid, base and salt, according to their nature. The substance whose nature is acidic (sour in test), called acid and whose nature is basic (bitter in test) is called base. Litmus is the natural indicator and used for the testing of the solution. Litmus paper turns blue to red if the solution is acid, and it turns red to blue if the solution is base. Litmus paper is widely used in the chemical laboratory.
Look at the following picture of Litmus
Acid Base
The natural colour of litmus is purple. Litmus is obtained from a type of tree called lichen. The colour of the natural litmus is converted into red and blue for the application in chemical experiment.
Look at the Following Picture of Lichen (Source of Litmus)
Phenolphthalein is a solution used as an indicator in the chemical laboratory it is a synthetic indicator. Colour of phenolphthalein does not change in the acidic solution, while in the basic solution it turns into pink colour
Look at the Following Picture of Phenolphthalein in Indicator
In the above picture, there are three beakers, one has phenolphthalein. If we Put a drop of acid into it, the colour of does not change. But if we put a drop of base into it, the color of indicator turns into pink. Again a drop of acid into the pink colored beaker turns it colorless- Acid cancels the effect of the basic component. The substance whose colour does not change in any solution of indicator is called neutral substance. The ch.na rose is also used as the indicator and called natural indicator Acids turn china rose indicator into magenta (deep pink). Bases turn China rose indicator into green. Another indicator is turmeric paper. In the acidic solution it turns into yellow. In the basic solution, it turns into red. Ph value is used to show the nature of the solution.
|