Call Now
1800-102-2727Have you ever wondered why lemon tastes sour while soda tastes bitter?
Well, this is due to the acidic nature of lemon juice and the basic nature of soda. Differentiating between common acidic and basic substances such as lemon juice, tamarind, soda etc is quite easy.
How would you distinguish whether a substance is acidic or basic if two unknown liquid samples are given to you?
One of the best methods is to use acid-base indicators such as litmus paper, phenolphthalein or methyl orange indicators.
What if there are no indicators available in the laboratory? How would you identify them in this scenario?
In this case, we have to study their chemical properties. Let’s understand some of the concepts of acid and base, and their chemical properties and will see the differences between acids and bases.
Table of Content
The substances which are sour in taste are called acids and the substances which are bitter in taste are bases. But this is not always true. Moreover, determining any chemical with taste is not an appropriate method to distinguish between acids and bases. It is highly dangerous. Hence, several new methodologies were discovered. Depending on how one chooses to see the characteristics of acidity and basicity, the terms acid and base have been defined in a variety of ways.
There are three different theories that have been put out to characterise acids and bases. These theories include the Arrhenius theory of acids and bases, Bronsted-Lowry theory and Lewis theory of acids and bases.
The Arrhenius theory states that an acid is a substance that releases an ion when dissolved in water. It raises the amount of
ions present in the solution. The base is a substance that dissolves in water and furnishes the
ions. It raises the amount of
ions present in the solution.
Example of an acid:
undergoes a dissociation reaction to produce
and
ions when dissolved in water. Due to this the concentration of
ions is increased.
Example of a base:
undergoes a dissociation reaction to produce
and
ions when dissolved in water. Due to this, the concentration of
ions is increased.
The base is a substance that accepts an ion or a proton to form its conjugate acid, and the acid is a substance that donates an
ion or a proton to form its conjugate base, according to the Bronsted-Lowry theory.
Examples:
(Here,
is an acid and
is its conjugate base)
(Here,
is an acid and
is its conjugate base)
Examples:
(Here,
is a base and
is its conjugate acid)
(Here,
is a base and
is its conjugate acid)
According to the Lewis definition, bases are described as molecules or ions that can donate the unshared electron pairs while the molecules or ions that can accept the unshared electron pairs are acidic in nature.
Lewis acids:
Lewis bases:
Properties of Acids
Properties of Bases
Parameters | Acids | Bases |
Definition |
|
|
Litmus test |
Acids cause blue litmus paper to turn red.
|
Bases cause red litmus paper to turn blue.
|
Flavour | Acids are sour in taste. |
Bases taste bitter and feel soapy when touched.
|
pH range |
|
|
Examples |
|
Q 1 According to Arrhenius theory any molecule that loses proton is:
a. an acid
b. a base
c. a salt
d. None of the above
Answer: (A)
According to Arrhenius theory, any molecule that releases protons in its aqueous solution is an acid. Hence, option A is the correct choice.
Q 2 Acid changes blue litmus paper into_____
a. Red
b. Violet
c. Green
d. white
Answer: (A)
Acid causes blue litmus paper to turn red whereas base turns red coloured litmus paper top blue. Hence, option A is the correct choice.
Q 3 Which of the following is not a lewis acid?
a.
b.
c.
d.
Answer: (C)
A molecule must lack electrons in order to be acidic in the Lewis sense, and it must be able to share electrons in order to be basic. ,
,
are Lewis acids as these three have the capacity to accept the electrons, whereas
is a Lewis base because it can donate the electrons. Hence, option D is the correct choice.
Q 4 Which of the following is not a property of base?
a. When touched, they are supposed to feel soapy.
b. Bases have pH readings typically lower than 7.
c. Bases have pH values higher than seven.
d. Bases turn red litmus paper blue.
Answer: (B)
Bases have the following properties:
pH reading is lower than 7 for acidic substances. Hence, option B is the correct choice.
Q1. What happens when an acid and a base are combined?
Answer: When an acid and a base are combined, they react to neutralise each other's effects and produce salt and water. Water is formed when the anion of the base and the
cation of the acid combine.
For example:
Q2. Can we mix acid with water?
Answer: When water is added to the concentrated acid. The solution boils violently, sputtering concentrated acid. After some time a very diluted solution results and the little heat that is released is insufficient to cause it to vaporise and spatter. So, water easily mixes with the acid and forms a diluted solution of acid.
Q3. Is coffee a base or an acid?
Answer: The majority of coffee varieties have an acidic pH range of 4.85 to 5.10. The brewing process releases many acidic substances (Malic, lactic, quinic, phosphoric, linoleic, chlorogenic, acetic, and palmitic acids) among the countless other compounds in this beverage, which give it a distinctive flavour profile.
Q4. Can you name any bases found in the human body?
Answer: Adenine, Cytosine, Guanine, and Thymine are the four distinct nitrogen-based bases found in DNA (a complex nucleic acid found in cells). The genetic makeup of all human life is determined by various combinations of these four bases.
Related Topics
Nuetralisation Reaction | Difference between alkali and base |
Physical and Chemical changes | Chemical composition |
Mixtures | Difference between mixtures and solutions |