10th Class Chemistry Chapter 2 Acids Bases and Salts Complete Solved Exercise

Class 10^th Chemistry

Chapter Acids Bases and Salts solved exercise:

Encircle the correct answer:

1)Which of the following cannot be classified as Arrhenius acid.

HNO₃
H₂CO₃
CO₂
H₂SO₄

Explanation:

Arrhenius theory:

This idea states that Arrhenius acid is a chemical that produces a proton when ionized in water. While carbon dioxide doesn’t contain any hydrogen atoms. So, upon ionization, it does not produce a proton. Because of this, it is not categorized as Arrhenius acid.

Watch-> Arrhenius Concept of Acids and Bases

2)NH₃ cannot be classified as base by

Lewis theory
Bronsted-Lowery theory
Arrhenius theory
All of these

Explanation:

Arrhenius Theory:

The term “Arrhenius base” refers to a chemical that, upon ionization in water, produces an OH^–ion. While ammonia doesn’t contain OH. So, upon ionization, it does not produce an OH^– ion. Consequently, it is not categorized as an Arrhenius base.

3)Which of the following is a Lewis base

BF₃
HCl
AlCl₃
F^–

Explanation:

Lewis Base:

Lewis defined a material as containing a single electron pair. Lewis base is a compound that can give electrons to electron-deficient centres. Here, only F^– has a single electron pair. It is categorized as a Lewis base because of this.

4)A drain cleaner solution contains 1 x 10^-8M, OH- concentration. The solution is

Acidic
Basic
Neutral
Cannot be predicted

Explanation:

If [OH^–] = 1 x 10^-8 M

Then it means that [H⁺] > [OH^–]

1 x 10^-7 > 1 x 10^-8

We also know that a solution is acidic when the concentration of hydrogen ions exceeds that of hydroxyl ions.

Milk of magnesia contains Mg(OH)₂. It is used as antacid. It neutralizes excess stomach acid. Which salt is formed in this reaction?

MgSO₄
MgCO₃
MgCl₂
MgO

Explanation:

6)Ammonia is a base, because it

Ionizes in water to give OH^– ions
Contains OH group
Can accept an electron pair
Can accept proton

Explanation:

Lewis Base:

Lewis defined a material as a Lewis base if it has the capacity to absorb or donate a proton or a lone pair of electrons. Ammonia here satisfies these requirements. Ammonia is a Lewis base thus.

7)Consider the following reactions?

Which species is an electron pair acceptor in this reaction?

H₂O
HCl
H₃O⁺
None

Explanation:

8)In the following reaction which species is donating an electron pair?

H
B
N
BF₃

Explanation:

9)An aqueous solution of NaOH is used as a drain cleaner. If the concentration of OH^– ions in this solution is 1 x 10^-5 M, the concentration of H⁺ ions in it would be?

1.0 x 10^-5 M
1.0 x 10^-7 M
1.0 x 10^-9 M
1.0 x 10^-14 M

Explanation:

We know that [H⁺] [OH^–] = 1 x 10^-14

So, if [OH^–] = 1 x 10^-5 then [H⁺] would be

[H⁺] = 1 x 10^-14 – [OH^–] = 1 x 10^-14 – 1 x 10^-5 = 1 x 10^-9

10)pH indicator is

Methyl violet
Methyl red
Phenol red
All of them

Explanation:

Methyl violet, methyl red, and phenol red are three of the eleven most widely used pH indicators.

——————————————–

Give short answers:

1) Create the water’s self-ionization equation.

When just water molecules are present in a container, the water molecules can self-ionize by one water molecule giving a proton (H⁺) and turning it into OH^–, while another water molecule accepts this proton (H⁺) and transforms it into H₃O⁺.

For instance:

We are aware of:

Self-Ionization of water can be represented as:

Mechanism of Reaction:

Explanation:

The aforementioned chemical mechanism demonstrates the self-ionization of water. It can be seen that,

One water molecule donates a proton (H⁺) to another, which accepts the proton (H⁺) and produces H₃O⁺.
This process is known as water self-ionization.
One water molecule acts as an acid by giving a proton
Whereas another acts as a base by taking a proton.

Point to Recall:

Water is a weak electrolyte, therefore self-ionization only occurs to a very limited amount in it. Its ionization power is thus low.

2) Describe Arrhenius acids and provide examples.

Arrhenius Theory is the response.

This hypothesis introduced the idea of bases and acids.
Svante Arrhenius, a Swedish scientist, proposed it in 1887.

As stated by Arrhenius:

Acid:

Acids are substances that, upon ionization, create H⁺ ions in the water solvent.

Figure 1:

Below is an example to illustrate this concept:

However, the Arrhenius principle stipulates that,

An acid must produce H⁺ ions in water on ionization.
As can be seen in the preceding process, hydrochloric acid produces H⁺ and Cl^– ions.
According to the Arrhenius idea, HCl is an acid since it created an H+ ion upon ionization in water, as seen in the reaction above.

Example 2:

Explanation:

In this reaction,

HNO₃ ionization into water results in the production of H⁺ and NO₃^-1 ions.
The Arrhenius theory, however, stipulates that an acid’s ionization in water must result in the production of H⁺ ions.
This reaction demonstrates that HNO₃ did indeed form an H+ ion when it was ionized in water.
Thus, HNO₃ is an acid in accordance with the Arrhenius theory.

Example 3:

Explanation:

We can observe from this reaction that,

2H⁺ and SO₄^-2 ions are produced when H₂SO₄ is ionized with water.
The Arrhenius theory, however, stipulates that an acid’s ionization in water must result in the production of H⁺ ions.
We can see from this reaction that H₂SO₄ did indeed form 2H⁺ ions upon ionization in water.
Thus, H₂SO₄ is an acid in accordance with the Arrhenius principle.

3): Why does the H+ ion function as a Lewis acid?

Response: Lewis Theory

Acid:

Lewis defined an acid as a species with the capacity to accept a single pair of electrons.

Since H+ has an electron-deficient core, we know from the definition that it can accept a lone pair of electrons (The duplet of Hydrogen is empty).

4): Why does NH₃serve as the Bronsted-Lowery base?

Referring to the Bronsted-Lowery Theory

In line with this hypothesis:

Base:

The term “base” refers to a species that can receive protons (H⁺).

For instance:

Explanation:

This process demonstrates that,

When ammonia (NH₃) and water (H₂O) are combined, the water donates a proton (H⁺), and the NH₃ accepts the proton (H⁺).
So, in this approach, NH₃ functions as a base and water as an acid.

Watch –> Bronsted Lowery Concept of Acid and Base

5): Why does BF₃ function as a Lewis acid?

Answer: Lewis Theory

Base:

Lewis states that a base is a species that has the capacity to give a lone pair of electrons.

Example:

Explanation:

The reaction can be summarized as;

The electron-deficient core of BF₃ is receiving a lone pair of electrons from ammonia (NH₃) in this reaction.
Thus, lone pair-donating species (NH₃) behaves like a base whereas electron-accepting species (BF₃) behaves like an acid in accordance with the Lewis concept.
BF₃‘s electron deficient core allows it to take lone pairs of electrons. Boron’s octet is lacking one element.
Therefore, Boron will receive a lone pair of electrons to complete its octet.
In addition, NH₃ and BF₃ form a coordinate covalent bond, which is symbolized by a single headed arrow. This bond is created by sharing a full lone pair of electrons with an electron-deficient specie.

Answer:

7) Recognize the Bronsted-Lowery bases or acids in the subsequent reactions.

Answer: In line with the Bronsted-Lowery Theory:

Acid:

A species is referred to as an acid if it has the ability to donate a proton (H⁺) to another species.

Base:

A specie that accepts the proton (H⁺) is referred to as a base. This specie was previously mentioned as another specie in the definition of an acid.

Reaction I demonstrates that,

HNO₃ behaves like an acid by donating proton while H₂O behaves like a base by accepting proton.
As a result, water becomes H₃O⁺ by accepting proton while acid becomes NO^3-.

As can be seen in reaction (ii),

HNO₃ is giving off protons while NH₃ is accepting them.
As a result, HNO₃ is acting as acid by giving off protons while NH₃ is acting as a base by accepting proton.

8) In the subsequent processes, distinguish between the Lewis acids and bases.

Answer: According to Lewis Theory:

Acid:

A species that can accept a lone pair of electrons is referred to as an acid.

Base:

A species that has the capacity to give away a single pair of electrons is referred to as a base.

Reaction I demonstrates that:

The incomplete octet of boron in BF₃ makes it electron deficient centre
In contrast, F^– only has one pair of electrons.
Therefore, F^– behaves as a base by donating a lone pair of electrons.
While BF₃ behaves like an acid by absorbing a lone pair of electrons

In reaction (ii), we can observe that:

H⁺ is an electron-deficient centre
NH₃ has a lone pair of electrons
NH₃ behaves as a base by donating lone pairs of electrons
H⁺ behaves as an acid by receiving lone pairs of electrons.

We may observe from reaction (iii) that:

AlCl₃ possesses an electron-deficient core because Al have incomplete octet
Since NH₃ has a lone pair of electrons, it acts as a base by giving those electrons to other molecules.
While AlCl₃ behaves as an acid by absorbing a line pair of electrons

Watch –> Lewis Acids and Bases

Watch –> Is H+ ion acts as a Lewis acid

9) Label the following mixtures as neutral, basic, or acidic.

A solution that has hydrogen ion concentration 1.0 x 10^-3 M
A solution that has hydrogen ion concentration 1.0 x 10^-10 M
A solution that has hydroxyl ion concentration 1.0 x 10^-3 M
A solution that has hydroxyl ion concentration 1.0 x 10^-10 M

Answer:

(i)

If a solution has hydrogen ion concentration 1.0 x 10^-3 M. Then the solution is acidic because

The exponent of 10 is (-3) , pH = – log [1.0 x 10^-3] = – log (10^-3) – log 1 = – (-3) – log 1 = 3 – 0 = 3

pH = 3

And we know that pH of acids ranging from 0-6

(ii)

If a solution has hydrogen ion concentration 1.0 x 10^-10 M. Then the solution is basic because

The exponent of 10 is (-10) so, pH = – log [1.0 x 10^-10] = – log (10-10) – log 1 = – (-10) – log 1 = 10 – 0 = 10

pH = + 10

And we know that pH of bass ranging from 8-14

(iii)

If a solution has hydroxyl ion concentration 1.0 x 10^-3 M. Then the solution is basic because

The exponent of 10 is (-3) so, pOH = – log [1.0 x 10^-3] = – log (10^-3) – log 1 = – (-3) – log 1 = 3 – 0 = 3

pOH = = +3

We know that, pH + pOH = 14

pH = 14-pOH

pH = 14-3 = 11

And we know that pH of bases ranging from 8-14

(iv)

If a solution has hydroxyl ion concentration 1.0 x 10^-10 M. Then the solution is acidic because

The exponent of 10 is (-10) so, pOH = – log [1.0 x 10^-10] = – log (10^-10) – log 1 = – (-10) – log 1 = 10 – 0 = 10

pOH = + 10

We know that, pH + pOH = 14

pH = 14-pOH

pH = 14-10 = 4

And we know that pH of acids ranging from 0-6

10) Group the following compounds into the Lewis acid and base categories.

BF₃, NH₃, F^–, H₂O,

Answer:

NH₃:

Ammonia is known as a Lewis base because it has a single pair of electrons that it is able to give to species lacking in electrons. Lewis further claims that a lone pair donating species is known as an acid.

F^–:

Because it has a lone pair of electrons, F^– is known as a Lewis base. Which it can easily donate to species lacking in electrons. Lewis further claims that a lone pair donating species is known as an acid.

H₂O:

Because it has a lone pair of electrons, water is known as a Lewis base. Which it can easily donate to species lacking in electrons. Lewis further claims that a single electron pair donating species is known as an acid.

BF₃:

Because boron possesses an electron-deficient centre in BF₃ due to an incomplete octet, the compound is known as a Lewis acid. Its octet need a single pair of electrons to complete it.

11. State the acid’s Bronsted-Lowery definition. Describe the definition with an equation.

Answer: According to Bronsted-Lowery:

Acid:

An acid is a species that can donate a proton (H⁺) to another species, while

For instance:

Explanation:

We can observe from this process that when ammonia (NH₃) and water (H₂O) were combined, the water provided protons (H⁺) and the NH₃ absorbed them. So, in this approach, NH₃ functions as a base and water as an acid.

12. Recognize the Bronsted-Lowery bases and acids in the subsequent reactions.

Answer:

(i)

In this reaction, we can see that,

The acetic acid, CH₃COOH, is giving a proton to the water
Which means that, in accordance with the Bronsted-Lowery theory, the acetic acid is acting like an acid since it is giving a proton to the water.
Additionally, water behaves as a base by absorbing proton

(ii)

In this reaction, we can observe that,

HCO₃^–donates a proton and water accepts a proton.
Therefore, according to the Bronsted-Lowery hypothesis, HCO₃^– behaves as an acid when it donates a proton
And water as a base when it accepts a proton

(iii)

This response demonstrates that.

According to the Bronsted-Lowery theory, because water (H₂O) is providing protons
Whereas ammonia (NH₃) is receiving them,
So, water behaves as an acid because it is donating protons.
And ammonia act as a base by taking on the proton NH₃.

(iv)

In this reaction, we can observe that,

HCO₃^– is receiving proton while HCl is providing proton
Therefore, according to the Bronsted-Lowery hypothesis, HCl is acting as an acid by accepting proton
While HCO₃^– is acting as a base by donating proton.

(v)

In this reaction, it can be seen that,

HS^– is donating proton and H₂O is accepting proton.
Therefore, the Bronsted-Lowery theory states that HS- is acting as an acid by donating proton
And H₂O is acting as a base by accepting proton.

13. Recognize the Lewis bases and acids in the subsequent reactions.

How to identify Lewis acid and base — Lewis acid and base identification

Answer:

(i)

This reaction demonstrates that,

By taking a lone pair of electrons, the electron-deficient centre H⁺ will behave as an acid
And by donating a lone pair of electrons, the electron-rich centre CN^– will behave as a base.

(ii)

This reaction demonstrates that,

B(OH)₃ has an electron deficient core because the boron octet is incomplete.
According to Lewis theory, OH^– possesses a lone pair of electrons.
As a result, by absorbing a lone pair of electrons, B(OH)₃ acts as an acid, and by donating a lone pair of electrons, OH^– acts as a base.

(iii)

This reaction demonstrates that,

Because NH₃ possesses a lone pair of electrons and Cu⁺² is an electron deficient centre
In this reaction, Cu⁺² behaves as an acid by accepting the lone pair of electrons.
In addition, NH₃ acts as a base by giving a lone pair of electrons.

(iv)

We may see from this reaction that:

In Al(OH)₃ (Al) has an electron-deficient core because of incomplete octect
According to Lewis theory, Al(OH)₃ behaves as an acid by accepting the lone pair of electrons that OH^– has.
Additionally, OH^– acts as a base by contributing a lone pair of electrons.

14) From the list below, pick out the Lewis bases and acids.

AlCl₃, Ag⁺, CH₃-OH, CH₃-NH₂, FeCl₃

Answer:

AlCl₃:

Due to the incomplete Al octet, AlCl₃ possesses an electron deficient centre.
Lewis refers to an electron deficient specie as an acid.
AlCl₃ is a Lewis acid, then.

Ag⁺:

Ag⁺ is an electron-deficient centre,
And according to Lewis, an acid is a species that is electron-deficient.
Ag⁺ is a Lewis acid, then.

CH₃-OH:

Lewis defined lone pair donating specie as base.
CH₃-OH has a lone pair of electrons (on the oxygen atom).
CH₃-OH is a Lewis base, then.

CH3-NH2:

Lewis defined lone pair donating specie as base.
CH₃-NH₂ has a lone pair of electrons (on the nitrogen atom).
CH₃-NH₂ is a Lewis base, then.

FeCl3:

Due to the incomplete octet of the Fe atom, FeCl₃ possesses an electron deficient centre
According to Lewis, an electron deficient specie is referred to as an acid.
FeCl₃ is a Lewis acid, then.

15) Identify whether water is a proton acceptor or donor.

Answer:

A special word (amphoteric) is used for water. It is because

Water can act as an acid by donating proton e.g.

Explanation:

We can observe from this process that when ammonia (NH3) and water (H2O) were combined, the water provided protons (H+) and the NH3 absorbed them. So, in this approach, NH3 functions as a base and water as an acid.

Water can act as a base by accepting proton e.g.

Explanation:

In this example, we can see that when HCl is given to water (H2O), the proton (H+) that HCl donates to the water (H2O) is accepted by the water (H2O) in the reaction’s mechanism. Therefore, water (H2O) is a base because it receives (H+), whereas HCl is an acid since it contributes (H+) according to the Bronsted-Lowery theory.

16) Create equations that depict the following Arrhenius acids being ionized.

HI
HNO₂

Answer:

Ionization equation for HI:

Ionization equation fore HNO₂:

17) Create equations demonstrating how the following Bronsted-Lowery acids ionize.

Answer:

Ionization Equation for HNO₂ and HCN:

Ionization equations of HNO2 and HCN — Ionization equations

18) What is the difference between the relative amounts of hydrogen and hydroxide ions in each type of solution?

Acidic
Basic
Neutral

Answer:

Acidic:

In acidic solution [H⁺] > [OH^–]

Basic:

In basic solution [H⁺] < [OH^–]

Neutral:

In neutral solution [H⁺] = [OH^–]

19) Codeine, chemical formula C₁₈H₂₁NO₃, is a frequent analgesic. The following reaction causes it to dissolve in water.

reaction between Codeine and water — Codeine and water reaction

Answer:

According to the Bronsted-Lowery theory,

Because water is donating proton in the aforementioned reaction
And codeine is accepting proton
Water behaves as an acid because it is donating proton.
In addition, codeine acts as a base by accepting proton

20) Consider a few methods for figuring out whether a specific water solution contains an acid or a base.

Answer:

We can predict nature of any solution by three ways:

pH paper:

Utilization of pH Paper:

If someone gave us a solution and instructed us to determine whether it was basic, neutral, or acidic, we would do so. Then, for this, we’ll take the following actions:

Take a small piece of pH paper
Dip it in a solution
Then, note the color of the pH paper
Match the color of pH paper with the pH scale
If its color matches with any number from 0-6 then the solution is acidic
If the color matches with 7 then the solution is neutral
If the color matches with any number from 8-14 then the solution is basic.
Litmus paper

Litmus paper is of two types:

Red litmus paper
Blue litmus paper

Utilization of Litmus Paper:

Individual test tubes should be used to collect samples of unknown solutions.
The test tubes should be labelled.
Red and blue litmus paper should be dipped into each solution.
Note the color shift
If the red litmus paper turns blue, the solution is basic
If the blue litmus paper turns red, the solution is acidic

pH indicator

Utilization of pH Indicator:

Add a few drops of indicator to a solution whose pH is unknown.
Watch for color changes.
Compare the color to the pH color chart for universal indicators.
Acids’ color shifts from green to red, and bases’ color shifts from green to purple.
If a universal indication pH color chart’s 0–6 color range matches the color, the solution is acidic.
The solution is neutral if the color matches the color at 7 on a universal indicator pH color chart.
If the color matches the colors between 8 and 14 on the same color chart, the solution is basic.

21)

What color will the indication A be?
In a solution of pH 3
In a solution of pH 10
What color will the indicator B be in a pH 5 solution?
A solution X immediately turns red when a few drops of indicator B are added to it. Evaluate the answer X’s characteristics?

Answer:

(i) Color of indicator A at pH 3:

When a solution has a pH of 3, indicator A turns color. The solution will then be red in color, indicating that it is acidic.

Color of indicator A at pH is 10:

If a solution’s pH is 10, indicator A will be colorless. If so, it denotes that the solution is basic, and its color will be blue.

b): When pH is 5, indicator B’s color is:

If a solution has a pH of 5. The solution is then described as acidic and colorless.

c): If a few drops of the pH-5 indicator B are poured into a solution and it turns red, the solution is basic, and its characteristics will be;

Bitter taste
Inability to change the color of blue litmus paper
Ability to turn the color of red litmus paper to blue
Ability to cause skin corrosion
Ability to conduct electricity

22) The bacteria in our mouth convert food debris attached to our teeth into acid as they feed. A toothpaste with a pH of 10 can assist in protecting our teeth from acid damage. Justify the assertion.

Answer:

The basic composition of toothpaste with a pH of 10 helps to neutralize the acids that cause tooth decay.

23) Is it possible for a substance to be both a Lewis acid and a Bronsted-Lowery acid? Argue.

Answer: Yes because;

According to Lewis theory, lone pair of electron accepting specie with an electron deficient centre is referred to as an acid.
According to Bronsted-Lowery theory, proton-donating specie is referred to as an acid.
Consequently, both theories’ conceptions of an acid are distinct.
While Lewis concept is about accepting a lone pair of electrons,
Bronsted-Lowery only discuss the H⁺ ion. We may therefore claim that all Bronsted-Lowery acids are Lewis acids.
But all Lewis acids are not acids according to Bronsted-Lowery theory

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Chapter Acids bases and salts important mcqs

Chapter Acids Bases and Salts Important Questions

Chapter Acids Bases and Salts Notes

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Chapter Chemical Equilibrium important questions

Chapter Chemical Equilibrium notes

-> Click to Watch Chemistry Chapter Chemical Equilibrium Tutorials

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