Chemcial Properties of Acids and Bases

Key Concepts

• Reaction of acids with metal, metal carbonates
• Reaction of acids with bicarbonates
• Reaction of base with oxides of non metals
• Reaction of bases with metals oxides

Introduction of Properties of Acids and Bases

Acids: Acids are sour to taste and turn blue litmus to red. Acids when dissolve in water release H⁺ ions. Acid solution contains conducts electricity. Acids are divided into two different type that is natural acids and mineral acid. Acids are of two kind strong acids and weak base. 

Bases are bitter in taste and has soapy to touch and which turn red litmus to blue. Bases dissolve in water release OH^– ions. It conducts electricity in solution. Bases are divided into two different types, they are water soluble and water insoluble. Bases are of two kinds: Strong base and weak base. 

Explanation: 

Now, let’s learn the chemical properties of acids and bases. 

Chemical properties of Acids and Bases 

Chemical properties of acids: 

Reaction of acids with metals: 

Take a conical flask or the test tube and add 5 ml of sulphuric acid and a few pieces of zinc granules. Now keep burning the match stick near the mouth of the test tube. What do you observe? When the gas bumps with the pop sound, it is confirmed that the evolution of hydrogen gas. Touch the bottom of the test tube. What do you observe? As acid reacts with metal the surface of the tube gets hot.  

Acid on reacting with metal gives hydrogen  

Metal + Acid →Salt + Hydrogen 

When Zinc metal reacts with Hydrochloric acid it gives Zinc Chloride and Hydrogen gas. 

Reaction of acid with metal carbonates: 

When metal carbonates react with acids gives salt in addition to it carbon dioxide and water are also formed. 

Hydrochloric acid upon reaction with sodium carbonate gives carbon dioxide, sodium chloride and water. 

CO₂ gas evolved from the solution which can be analyzed by passing through the lime solution and then the lime solution turns milky white. 

When nitric acid reacts with sodium carbonate gives sodium nitrate, water, and carbon dioxide. 

Reaction of metal oxides with acids: 

We know that metal oxides are basic in nature. CaO, MgO are basic oxides. 

When metal oxide reacts with acids it gives salt and water respectively. 

Examples of Reaction of acids:  

1. Ca(OH)2+Cl2→CaOCl2+H2OCa(OH)2+Cl2→CaOCl2+H2O 

2. Ag2S+H2SO4→Ag2SO4+H2SAg2S+H2SO4→Ag2SO4+H2S 

3. NaOH+H2CO3→NaHCO3+H2ONaOH+H2CO3→NaHCO3+H2O 

Chemical properties of bases:  

Reaction of bases with metals:  

When bases react with metals it produces salt and hydrogen gas.  

Examples: Sodium hydroxide reacts with Zn metals give sodium zincate and hydrogen gas. 

The reaction of bases with metals carbonates: 

Bases do not react with metal carbonates as metal carbonates behave as a base. So, there is no reaction between the metal carbonates and bases. 

Sodium carbonate when reacted with sodium hydroxide, no reaction is visible and no product is formed. This is because both sodium hydroxide is itself derived from the salt in which the salt is sodium carbonate and sodium hydroxide acts as a base and it. 

The reaction of bases with oxides of Non-metals: 

Non-metal oxides are acidic in nature. Generally, CO₂ is a non-metal oxide. 

Non-metal oxides are generally acidic in nature. 

Non-metallic oxide + base ®  salt + H₂O 

CO₂ + Ca(OH)₂ ® CaCO₃ + H₂O 

Examples of reactions of bases:  

HCl(aq) + KOH(aq) ® H₂O(l) + KCl(aq) 

2HCl(aq) + Mg(OH)₂(aq) ®  2H₂O(l) + MgCl₂(aq) 

HCl(aq) + NH₃(aq) ® NH₄Cl(aq) 

Test to recognize acid/base: 

Take A test tube and add 1 gm of NaCl into it and add some amount of concentrated sulphuric acid. 

Now observe what happens in the test tube. Check whether any gas is coming out of the test tube. 
Test the gas evolved from the test tube with blue or red litmus paper. 

Blue litmus paper turns red as there is the presence of sulphuric acid in the test tube. 

What happens to the acid or base when it reacts with water: 

The hydrogen ion in HCl is produced when it reacts with or in the presence of water. The separation of H⁺ion is not possible in the absence of a water molecule. 

HCl + H₂O ® H₃O⁺ + Cl^– 

Hydrogen ions cannot exist alone as it will only form when they react with a water molecule. Hydrogen ions will always be formed as H⁺ion or H₃O⁺ ion. 

H⁺ + H₂O ® H₃O⁺ 

Bases generally generate hydroxide ions in water. Alkalis are the substances in which bases are dissolved in water. 

We can conclude that acids will generate H⁺ ions whereas bases generate OH^– ions and we finally call that combination as neutralization reaction. 

Summary

• Acid on reacting with metal gives hydrogen. • Non-metal oxides are acidic in nature. Generally, CO2 is a non-metal oxide.
• Bases do not react with metal carbonates as metal carbonates behave as a base. So, there is no reaction between the metal carbonates and bases.
• When bases react with metals it produces salt and hydrogen gas. When metal oxide reacts with acids it gives salt and water respectively.
• Bases generally generate hydroxide ions in water. Alkalis are the substances in which
• bases are dissolved in water.
• Hydrogen ions cannot exist alone as it will only form when they react with a water molecule. Hydrogen ions will always be formed as H+ion or H3O+ ion.