Answer the following questions.
a. Classify the acids according to their basicity and give one examplen of each type.
b. What is meant by neutralization? Give two examples from everyday life of the neutralization reaction.
c. Explain what is meant by electrolysis of water. Write the electrode reactions and explain them.
a. Classify the acids according to their basicity and give one examplen of each type.
Ans 8.
a. The number of ionizable hydrogen (H+) ions present in one molecule af an acid is called its basicity.
For example :
HCl ---------> H+ + Cl-
Basicity of HCl is 1.
H2SO4 ------> 2H+ + SO42-
Basicity of H2SO4 is 2.
Based on Basicity acids were classified into different types :
1. Mono-basic acids
2. Di-basic acids
3. Tri-basic acids
1. Mono-basic acids :
Acids, which on ionisation produce one hydronium ion on reaction with water.
Acids, which on ionisation produce one hydrogen ion.
For example : HCl, HNO3 etc.
2. Di-basic acids :
Acids, which on ionisation produce two hydronium ion on reaction with water
Acids, which on ionisation produce two hydrogen ion
For example : H2SO4, H2CO3 etc.
3. Tri-basic acids :
Acids, which on ionisation produce three hydronium ion on reaction with water
Acids, which on ionisation produce three hydrogen ion
For example : H3PO4, H3PO3 etc.
b. Neutralization reaction :
A neutralization reaction is a reaction in which an acid and a base reacts to form water and a salt. It involves the combination of H+ ions and OH- ions to generate water.
The neutralization of a strong acid and strong base has a pH equal to 7.
The neutralization of a strong acid and weak base will have a pH of less than 7.
The neutralization of a strong base neutralizes a weak acid will be greater than 7.
When a solution is neutralized, it means that salts are formed from equal weights of acid and base.
Neutralization reaction has application in daily life:
1)Self defence by animals and plants through chemical warfare :
Bee stings are acidic in nature, household remedy for a bee sting is baking soda or sodium bicarbonate, which is a basic substance.
A wasp stings are mildly basic, household remedy for this will be vinegar, also known as acetic acid.
These simple treatments ease these painful stings by a process called neutralization.
2)pH in our digestive system :
An acidic stomach due to eating too much spicy food, can be relieved by taking an antacid. The antacid is alkaline/basic in nature and helps to neutralize the stomach's acidity or you may take magnesium hydroxide(Milk of magnesia) and sodium hydrogen carbonate(Baking soda).
3) pH change as the cause of tooth decay :
When we eat food containing sugar, then bacteria present in our mouth break down the sugar to form acids(such as lactic acid). Thus acid is formed in the mouth after digestion. This will lead to the cause of tooth decay. The best way to prevent tooth decay is to clean the mouth after eation food with toothpaste, which is basic in nature. This will result in neutralization of acid by base.
4)soil pH and plant growth :
Most of the plants grow best when the pH of the soil is close to 7 that's neural. If the soil is too acidic or too basic(alkaline), the plants grow badly.
The acidic soil is neautralize by treatment with materials like quicklime(calcium oxide) or slaked lime(calcium hydroxide) or chalk(calcium carbonate).
If the soil is too basic, then alkalinity can be reduced by adding decaying organic matter(manure or composite)which contains acidic materials.
c.Electrolysis of water :
Electrolysis of water is the decompositon into oxygen and hydrogen gas due to an electric current passed through the water.
The following equation represents the electrolysis of water :H2O(l)
In pure water, at the negatively charged cathode, a reduction reaction takes place, with electrons (e−) from the cathode being given to hydrogen cations to form hydrogen gas.
- Reduction at cathode: 2 H+ + 2e− → H2
On positively charged anode, an oxidation reaction occurs, generating oxygen gas by giving electrons to the anode :
- Oxidation at anode: 2 H2O → O2(g) + 4 H+(aq) + 4e−
The same half reactions can also be balanced with base as listed below. To add half reactions they must be balanced with either acid or base.
Cathode (reduction):
2 H2O(l) + 2e−
→
H2(g) + 2 OH−(aq)
Anode (oxidation):
4 OH−(aq)
→
O2(g) + 2 H2O(l) + 4 e−
Combining either half reaction pair yields the same overall decomposition of water into oxygen and hydrogen:
- Overall reaction: 2 H2O(l) → 2 H2(g) + O2(g)
The number of hydrogen molecules produced is thus twice the number of oxygen molecules. The produced hydrogen gas has therefore twice the volume of the produced oxygen gas. The number of electrons pushed through the water is twice the number of generated hydrogen molecules and four times the number of generated oxygen molecules.
2H2O(l)⟶2H2(g)+O2(g)
Ans 8.
a. The number of ionizable hydrogen (H+) ions present in one molecule af an acid is called its basicity.
For example :
HCl ---------> H+ + Cl-
Basicity of HCl is 1.
H2SO4 ------> 2H+ + SO42-
Basicity of H2SO4 is 2.
Based on Basicity acids were classified into different types :
1. Mono-basic acids
2. Di-basic acids
3. Tri-basic acids
1. Mono-basic acids :
Acids, which on ionisation produce one hydronium ion on reaction with water.
Acids, which on ionisation produce one hydrogen ion.
For example : HCl, HNO3 etc.
2. Di-basic acids :
Acids, which on ionisation produce two hydronium ion on reaction with water
Acids, which on ionisation produce two hydrogen ion
For example : H2SO4, H2CO3 etc.
3. Tri-basic acids :
Acids, which on ionisation produce three hydronium ion on reaction with water
Acids, which on ionisation produce three hydrogen ion
For example : H3PO4, H3PO3 etc.
b. Neutralization reaction :
A neutralization reaction is a reaction in which an acid and a base reacts to form water and a salt. It involves the combination of H+ ions and OH- ions to generate water.
The neutralization of a strong acid and strong base has a pH equal to 7.
The neutralization of a strong acid and weak base will have a pH of less than 7.
The neutralization of a strong base neutralizes a weak acid will be greater than 7.
When a solution is neutralized, it means that salts are formed from equal weights of acid and base.
Neutralization reaction has application in daily life:
1)Self defence by animals and plants through chemical warfare :
Bee stings are acidic in nature, household remedy for a bee sting is baking soda or sodium bicarbonate, which is a basic substance.
A wasp stings are mildly basic, household remedy for this will be vinegar, also known as acetic acid.
These simple treatments ease these painful stings by a process called neutralization.
2)pH in our digestive system :
An acidic stomach due to eating too much spicy food, can be relieved by taking an antacid. The antacid is alkaline/basic in nature and helps to neutralize the stomach's acidity or you may take magnesium hydroxide(Milk of magnesia) and sodium hydrogen carbonate(Baking soda).
3) pH change as the cause of tooth decay :
When we eat food containing sugar, then bacteria present in our mouth break down the sugar to form acids(such as lactic acid). Thus acid is formed in the mouth after digestion. This will lead to the cause of tooth decay. The best way to prevent tooth decay is to clean the mouth after eation food with toothpaste, which is basic in nature. This will result in neutralization of acid by base.
4)soil pH and plant growth :
Most of the plants grow best when the pH of the soil is close to 7 that's neural. If the soil is too acidic or too basic(alkaline), the plants grow badly.
The acidic soil is neautralize by treatment with materials like quicklime(calcium oxide) or slaked lime(calcium hydroxide) or chalk(calcium carbonate).
If the soil is too basic, then alkalinity can be reduced by adding decaying organic matter(manure or composite)which contains acidic materials.
c.Electrolysis of water :
Electrolysis of water is the decompositon into oxygen and hydrogen gas due to an electric current passed through the water.
The following equation represents the electrolysis of water :H2O(l)
In pure water, at the negatively charged cathode, a reduction reaction takes place, with electrons (e−) from the cathode being given to hydrogen cations to form hydrogen gas.
- Reduction at cathode: 2 H+ + 2e− → H2
On positively charged anode, an oxidation reaction occurs, generating oxygen gas by giving electrons to the anode :
- Oxidation at anode: 2 H2O → O2(g) + 4 H+(aq) + 4e−
The same half reactions can also be balanced with base as listed below. To add half reactions they must be balanced with either acid or base.
| Cathode (reduction): | 2 H2O(l) + 2e− | → | H2(g) + 2 OH−(aq) |
| Anode (oxidation): | 4 OH−(aq) | → | O2(g) + 2 H2O(l) + 4 e− |
Combining either half reaction pair yields the same overall decomposition of water into oxygen and hydrogen:
- Overall reaction: 2 H2O(l) → 2 H2(g) + O2(g)
The number of hydrogen molecules produced is thus twice the number of oxygen molecules. The produced hydrogen gas has therefore twice the volume of the produced oxygen gas. The number of electrons pushed through the water is twice the number of generated hydrogen molecules and four times the number of generated oxygen molecules.
2H2O(l)⟶2H2(g)+O2(g)
