Introduction
What are Acids, Bases, and Salts?
Many acids and bases occur naturally in nature, such as citric acid in fruits like orange, lemon etc, tartaric acid in tamarind, malic acid in apples and lactic acid in milk and milk products, hydrochloric acid in gastric juices.
Similarly, many bases are found such as lime water. We use many of these acids in our day-to-day life, such as vinegar or acetic acid in the kitchen, boric acid for laundry, baking soda for the purpose of cooking, washing soda for cleaning etc.
Many of the acids that we do not consume in the household are used in the laboratories and industries, which include an acid such as HCl, H2SO4 etc. and bases such as NaOH, KOH etc. When these acids and bases are mixed in the right proportions, the neutralization reaction thus results in the formation of salt and water. Some naturally occurring salts found in nature include NaCl and KCl etc in seawater and natural rock deposits. In this section, we will read more about acid, base and salt and their properties.
Definitions
Acid:- An acid is defined as a substance whose water solution tastes sour, turns blue litmus red and neutralizes bases.
Base:- A substance is called base if its aqueous solution tastes bitter, turns red litmus blue or neutralizes acids.
Salt:- Salt is a neutral substance whose aqueous solution does not affect litmus.
Acids
The term acid is derived from a Latin word ‘acidus’ or ‘acere’, which means sour. The most common characteristic is their sour taste. An acid is a substance that renders ionizable hydronium ion (H3O+) in its aqueous solution. It turns blue litmus paper red. These dissociate in their aqueous solution to form their constituent ions, as given by the following examples.
HCl(aq) ⇒ H+ + Cl-
H2SO4(aq) ⇒ 2H+ + SO4^2-
Dissociation of Acids
Lime Juice is Acidic in Nature
Based on their occurrence, they are divided into two types- Natural and mineral acids.
Natural Acids: These are obtained from natural sources, such as fruits and animal products. For e.g. lactic, citric, and tartaric acid etc.
Mineral Acids: Mineral acids are acids prepared from minerals. For example, Hydrochloric acid (HCl), Sulphuric Acid (H2SO4), and nitric acid (HNO3) etc.
Also Check ⇒ Dilute Acids
Bases
The most common characteristic of bases is their bitter taste and soapy feel. A base is a substance that renders hydroxyl ion(OH–) in their aqueous solution. Bases turn the colour of red litmus paper to blue.
Many Cleaning Solutions are Basic in Nature
The bases dissociate in their aqueous solution to form their constituent ions, given by the following examples.
NaOH(aq) ⇒ Na+ + OH-
Ca(OH) 2 ⇒ Ca2+ +2OH-
Dissociation of Bases
Salts
Salt is an ionic compound that results from the neutralization reaction of acids and bases. Salts are constituted of positively charged ions, known as cations and negatively charged ions, known as anions, which can either be organic or inorganic in nature. These ions are present in a relative amount, thus rendering the nature of the salt neutral.
Many Naturally Occurring Rocks and Minerals are Salts
The formation of salt can be seen from the chemical reactions shown in the equations below.
HCl + NaOH ⇒ NaCl + H2O
H2SO4 + Ca(OH) 2 ⇒ CaSO4 + 2H2O
Neutralization Reactions of Acids and Bases
Task
Q. What are the 2 types of acids?
Q. Is NH4Cl a basic salt?
Q. What happens when base contact with litmus paper?
Q. What is salt in acid base and salt?
Q. What happens when salt reacts with HCl?
Process
Evaluation
Q1) Which Acid is present in Tomato ?
(A) Citric Acid
(B) Oxalic Acid
(C) Lactic Acid
(D) HCl
Q2) Which Acid is a strong Acid in the following:
(A) HCl pH 1
(B) CH3COOH pH 5
(C) Lemon juice pH 2.2
(D) Pure Milk pH 6
Q3) Na2CO3.10H2O is known as-
(A) Baking Soda
(B) Baking Powder
(C) Washing Soda
(D) Bleaching Powder
Q4) pH value less than 7 indicates that the solution is –
(A) Acidic
(B) Basic
(C) Neutral
(D) No effect
Q5) Which salt is Neutral salt?
(A) NH4Cl
(B) CH3COONH4
(C) CH3COONa
(D)Na2CO3
Q6) Lactic Acid is present in-
(A) Orange
(B) Tea
(C) Curd
(D) Vinegar
Q7) Farmers neutralize the effect of Acidity on soil by adding
(A) Slaked Lime
(B) Gypsum
(C) Caustic Soda
(D) Baking Soda
Q8) Which of the following are present in a dilute Aqueous solution of Hydrochloric Acid?
(A) H3O + Cl–
(B) H3O + OH–
(C) Cl– + OH–
(D) Unionised HCl
Q9) CuSO4.5H2O In this Compound the water molecule is called –
(A) Pure Water
(B) Water of Crystallisation
(C) Soda Water
(D) None of these
Q10) Which of the following salts does not contain water of crystallization?
(A) Blue vitriol
(B) Baking soda
(C) Washing soda
(D) Gypsum
Q11) An aqueous solution turns the red litmus solution blue. Excess addition of which of the following solutions would reverse the change?
(A) Baking powder
(B) Lime
(C) Ammonium hydroxide solution
(D) Hydrochloric acid
Q12) In which pH range does our body work to survive in the atmosphere?
(A) 5.5 to 8.5
(B) 7.0 to 7.8
(C) 2.3 to 7.0
(D) 7.5 to 12.5
Conclusion
Acid and base can be differentiate by the PH scale ( potential of hydrogen).
| 1 | 2 | 3 | 4 | 5 | 6 | 7 | 8 | 9 | 10 | 11 | 12 | 13 | 14 |
PH scale
PH value 7 = neutrality of solution
Ph value less than 7 = acidic nature of solution.
Ph value more than 7= basic nature of solution.
Less ph value shows strong acid and high value of ph shows strong base.