Class 10th Chemistry Notes Chapter 2 ACIDS, BASE AND SALTS

Table of Contents

Class 10th Chemistry Notes Chapter 2 ACIDS, BASE AND SALTS

Class 10th Chemistry Notes Chapter 2 ACIDS, BASE AND SALTS. What are acids, bases and salts?
Many acids and bases are found 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 dairy products, hydrochloride acid in gastric juices. Class 10th Chemistry Notes Chapter 2 ACIDS, BASE AND SALTS.

Class 10th Chemistry Notes Chapter 2 ACIDS, BASE AND SALTS
Class 10th Chemistry Notes Chapter 2 ACIDS, BASE AND SALTS

Similarly, many bases are found such as lime water. We use many of these acids in our daily lives, such as vinegar or acetic acid in the kitchen, boric acid for washing clothes, baking soda for cooking, sodium washing for cleaning, etc.Class 10th Chemistry Notes Chapter 2 ACIDS, BASE AND SALTS.

Class 10th Chemistry Notes Chapter 2 ACIDS, BASE AND SALTS
Class 10th Chemistry Notes Chapter 2 ACIDS, BASE AND SALTS
  • Table of Contents
  • Definitions
  • Recommended Videos
  • Acids
  • Bases
  • Frequently asked questions: frequently asked questions


Class 10th Chemistry Notes Chapter 2 ACIDS, BASE AND SALTS. Many of the acids that we do not consume at home are used in laboratories and industries, which include an acid such as HCl, H2SO4, etc. and bases like NaOH, KOH, etc. When these acids and bases are properly mixed in proportions, the neutralization reaction results in the formation of salt and water. Some natural salts found in nature include NaCl and KCl etc. in sea water and natural rock deposits. In this section, we will read more about acid, base, and salt and their properties. Class 10th Chemistry Notes Chapter 2 ACIDS, BASE AND SALTS.

SEE MORE NOTES: Class 10 Science Notes Chapter 1 Electricity in everyday life 2021

English Notes: Hazrat Umar Farooq (RA) The Model Millionaire, Class 10th Notes Free Download 2021

Chapter No.10

word image 41

Q.1. what is the origin of Acid? Give examples of acids, bases and salts substances in our daily life?

Ans. Origin of Acid:

The term acid is derived from Latin word -Acids- which means sour. So acids are those substances having sour taste.

Some important acids in our daily life:

Many important acidic substances which we use in our daily life are as under:

i. Acetic Acid:

It is found in vinegar.

ii. Lactic Acid:

It is found in fermented milk.

iii. Malic Acid:

It is found in apple.

iv. Citric Acid:

It is found in citrus fruits like lemon, orange, grapes etc.

v. Hydrochloric Acid:

It is found in our stomach which helps in the digestion of food.

vi. Formic Acid:

It is in sting of ants and bees

Some important bases and salts in our daily life:

There are many bases and salts which we use in our daily life. For example:

Washing Soda (Na2CO3 10H20):

It is a salt and is used for washing purposes.

ii. Baking Soda (NaHCO31:

It is also a salt and is used for baking of cakes and other confectionaries.

iii. Sodium Hydroxide (NaOH):

It is also called caustic soda which. Is used for the preparation of soap.

iv. Magnesium Hydroxide (Mg (OH) 2h

It is used as antacid

Compare the physical properties of acids and bases?

Ans. Comparison between physical properties of acids and bases: It is given in the table given below:

Acid

  1. Acid solution taste. has bitter

Acid solution turns blue litmus paper to red.

(iii) Strong acids ‘ are very

Base

Base solution has sour taste.

Base solution turns red litmus _Rapper to blue.

Strong bases are also very corrosive and damage skin corrosive but less corrosive as and other organic compared to strong acids.

• Substances. •

(iv) Acid solutions do not have Base solutions have soapy touch. soapy touch.

(v) Acids solutions conduct Base solutions can also conduct

Electric current. Electric current.

3: Describe the different concepts of acids and bases?

Ans. Different concepts about acids and bases:

The different concepts about acids and bases are described below: 1. The Arrhenius concept (The classical concept):

Introduction:

The first concept about acids and bases was presented by a Swedish chemist. Arrhenius in 1884.

Definitions of acids and bases:

According to this concept acids and bases are defined as follows:

Acid:

-The compound which gives I-1+ ions in water is called acid.- General Ionization Equation:

The general ionization equation for acid is given below.

HA. „

Base:

“The compound which gives OH- ions in water is called base.” General Ionization

Equation:

The general ionization equation for a base is given below: BO H (, i)

Examples of Arrhenius acids:

HCI, FI2SO4, HNO3, • HBr, HI CH3COOH etc. are some of the examples of Arrhenius acids because when these are added to water, they ionize to give H+ ions which react with water to form hydronium ions H30+. The chemical equations for the ionization of some acids are as follows:

HCI (aq) Fr (ac) Cr (aq)

H2SO4 (aq) 2H+ (aq) +so4″-(aq)

HNO3 (aq) H+ (aq) NO3 (aq)

Note: That hydronium ion (H30′) is formed by the reaction of H’ with H2O i.e.

H30+ (aq)

H+ (aq) + H20 (1) lo•

Examples of Arrhenius bases:

NaOH, KOH, Li0H, Ba (OH) 2, NH4OH, Al (OH) 3 etc. are the examples of Arrhenius bases because they give OH- ions in water. The chemical equations for the ionization of some of the bases are given below:

NaOHlacil KOH (acv Li0Fl (aci) + OH—(aq)

► K

Li_ + (aq) + 01-1-(aq) •

Summary:

Acid gives H” ion while base gives OH- ions in water.

Advantage:

+ It shows the strength of Acids and bases.

Limitations of Arrhenius Concept:

The limitations of Arrhenius concept are given below:

  1. Restriction to Aqueous Medium:

This concept is only limited to aqueous medium and it does not-explain the acidity and basicity of substances in non-aqueous medium.

ii. Restriction To W and OH’ Ions:

In this concept acids are limited to W while bases to OK ions only and it cannot explain the acidic nature of CO2 and basic nature of NH3.

2. The Bronsted-Lowry concept (The photonic concept):

Introduction:

This concept was presented by Danish chemist J.N Bronsted and English chemist T.M Lowry in 1923.

Definitions of acids and bases:

According to Bronsted-Lowry concept, acids are defined as the substances which donate protons (H+ ions), while bases are defined as the substances which accept protons.

Examples:

I. When ammonia (NH3) is added to water, the following reaction occurs:

HCI (aq) + NH3 (aq) –> NH; (aq) + Cr (aq)

Proton donor Proton acceptor in the above example the ammonia accepts a proton from HCI, therefore. It acts as a base while HCI donates a proton and therefore it acts as an acid.

Ii. H.

HCI + H20 H30+ + Cr

Acid Base

In the above example water accepts proton, therefore it acts as a base. NH3 (aq) + H2O + 011..

Base acid

In the above example water donates proton, therefore here water acts as an acid. Thus water is amphoteric.

Summary:

Acid is proton (H*) donor while base is proton acceptor_

Limitations of Bronsted-Lowry Concept:

Some bases like NaOH, KOH etc. cannot be explained on the basis of this concept because these cannot accept protons.

Ans: the Lewis concept:

Introduction:

G N Lewis presented his own concept of acids and bases in 1923. Definitions of acids and bases:

According to this concept an acid is a species that can accept or tends to accept a pair of electrons while a base is a species which can donate or tends to donate a pair of electrons.

An acid is electrophile (electron loving) while a base is a nucleophile (nucleus loving).

Species which acts as Lewis acids:

• Those compounds in which central atom has less than eight electrons in valance shell and positive ions act as Lewis acids i.e. they accept electron pair e.g. BF3. AICI3, etc.

• All captions are act as Lewis acids e.g. H’, Ag’

Species which acts as Lewis Bases:

• Those compounds which have lone pair of electrons in valance shell and negative ions, act as Lewis bases i.e. they donate electron pair e.g. NH3, H2O, etc.

• All anions act as Lewis bases. e.g., CN-, Cl- etc.

Examples: i. Consider the following reaction:

H F

NH3 + BF3 — F

I

H F J (Complex)

In the above example NH3 acts as a base (electron pair donor) while BF3 acts as a Lewis acid (electron pair acceptor).

What is meant by conjugate acid and • base? Explain with examples.

Ans. Conjugate acids:

“The positively charged species formed by a base after taking a proton is called conjugate acid of the corresponding base because it can give a proton.”

Examples:

I. NH3 (aq) + H2O r NH. + 011-

Base acid conjugate acid In the above example NH. is the conjugate acid of NH3.

It may be noted that a base and its conjugate acid differ from each other by one proton (H+) e.g. NH3 and NW, , H2O and H30+ etc.

ii. H2O + HCI H30+ +Cl-

Base acid conjugate acid

Conjugate bases:

The negatively charged species left after an acid donates proton is called conjugate base of that acid because it can accept a proton.” Examples:

i. When acetic acid gives a proton it forms acetate ion (OH3000-). Acetate ion is the conjugate base of acetic acid because it can accept a proton.

CH3COOH H2O CH3C00— I-1,0′

Acid base conjugate base

ii. HCI + H2O + H30+

Acid base conjugate base

It may be noted that acid and its conjugate base differ by one proton e.g. HCI and Cr HBr and Br- etc.

Describe the types of Acids?

Ans. Types of Acids:

On the basis of number of protons that can be given by an acid per molecule in water. There are the following types of acids:

i. Mono-parotic acids

ii. Poly-parotic acids

i. Mono-parotic acids:

“Those acids which give one proton per molecule are called monocratic acids or mono-basic acids.-

Examples:

HCI, HNO3. CH3COOH, HBr, HCN etc. are some of the examples of mono-parotic acids because they give only one proton per molecule. Their dissociation in water is as follows:

HCI „, r H+ (aq) + CI (.4)

H N 03 ;„,) H+ (aq) + NOT (aq)

CH3COOH, aq, —, Fr (Ag) + CH3C00-(aq)

HBr H+ (aq) + Br–(aq)

HCN •AA,

Hf (aci) + CN—(aq)

ii. Poly-protic acids:

“Those acics which give more than one protons per molecule are called poly-protic acids or poly-basic acids.”

These are further divided into the following sub-groups:

i. Di-protic acids:

“Those acids which give two protons per molecule are called diprotic acids or di-basic acids.”

Examples:

H2SO4, H2003 etc. are the examples of di-protic acids because they give two protons per molecule:

H2SO4 (aq) ► 21-1+ (aq) + so, (aq)

H2CO3 (aq) 2H+ (aq) + CO32 (aq)

ii. Tri-protic acids:

“Those acids that give three protons per molecule are called triprotic acids or tri-basic acids.”

Example:

Phosphoric acid is an example of tri-protic acid as clear from the following chemical equation:

H3PO43H+ (aq) PO4-3 (aq)

Q.6. Describe the types of Bases?

Ans. Types of Bases:

On the basis of number of OH- ions that can be given by an acid per molecule in water, there are the following types of bases:

i. Mono-acid bases

ii. Poly-acid bases

i. Mono-acid bases:

“Those bases which give one OK ion per molecule are called mono-acid bases.

Examples:

NaOH, KOH, LiOH, CsOH etc. are some of the examples of mono-acid bases because they give only one OH” ion per molecule. Their dissociation in water is as follows:

NaOH (aq) Na+ (aq) + 01-1-(aq)

KOH (aq) 4 K+ (aq) + OH-(aq)

Li°H (Ag) Li (aq) 01-1—(aq)

ii. Loly-3sis1 Bases:

“Those bases which give more than one Oft ions per molecule are called poly-acid bases”.

These are further divided. Into the following sub-groups:

Iii.Lime-acid Bases:

“Those Bases which give two OH” ions per molecule are called di acid bases”

Examples:

Mg (OH) 2, Be (OH) 2 etc. are the examples of di-acid bases because they give two OH” ions per molecule:

Mg (OH) 2(aq) _____► M9+2(aq) + 2oH

___-(aq)

Be (OH) 2 (aq)-■ be+2(aq) + 20H-(aq)

Iv.Tri-acid bases:

“Those bases that give three OH- ions per molecule are called triadic bases.”

Example:

Al (OH) 3, Fe (OH) 3 etc. are the examples of tri-acid bases as clear from the following chemical equations:

Al (OH) 3 (ac)–0. Al4-3? c) + 301-1-(aq)

Fe (OH) 3 (aq) Fe (am + 30Ff (aq)

*Q. What are amphoteric substances?

Ans. Amphoteric substances:

“Those substances which can act both as an acids and a base are called amphoteric substances.”

Examples:

i. Water is amoho. E’ic ocean se it acts as a base with an acid while it acts as an acia with a case

HCI + H—OH >H30+ + Cr

L): SE Corrugate Ana Conjugate base

NHS + H2O NEI: t + OH

Base and Conjugate

Acid base

ii. During self-ionization of water some water molecules acts as an acid while some acts as a base:

H2O + H2O H30+ + OH-

Acid Base Conjugate Conjugate

Acid base

Q.7. what are strong and weak acids? OR

Describe the strength of Acids?

Ans. Strong acids:

“Those acids which almost completely ionize in aqueous solutions and give higher concentration of ions are called strong acids.”

The solutions of strong acids contain ions and almost n unionized molecules are left.

Examples:

2 acids because t almost -…completely onize ‘n water

Fr. (aq) + Crag

Some other strong acids are given below:

Strong Acid Chemical Formula

(i) Perch! Uric acics HC 04

(ii)Nitric Acid HNO3

(iii)Sulphuric Acid H2SO4

(iv) Hydro iodic acid Hi

Weak acids:

“Those acids which partially ionize in water are called weak acids.” The solutions of weak acids in addition to ions also contain unionized molecules.

Examples:

When acetic acid is added to water, very few molecules are ionized; therefore acetic acid is a weak acid.

CH3COOH (aq) r H. as+ CH3C00-(aq)

Some other weak acids are given below:

Weak Acid

Chemical Formula

Phosphoric acid

H3PO4

Nitrous Acid

i HNO2

Sulphurous Acid

H2S03

Carbonic acid

H2003

in Pro anoic acid

C2HSO0017i •

Q.8. what are strong and weak bases? OR

Describe the strength of bases?

Ans. Strong bases:

“Those bases which dissociate almost completely in water are called strong bases.”

Strong bases completely ionize in water and almost no unionized molecule is left behind.

Examples:

Examples of some of the strong bases are given below:

Strong• Base

Chemical Formula

Sodium H dioxide

i

NaOH

Potassium Hydroxide I KOH

Lithium Hydroxide

‘ LiOH CsOH

Weak bases: •

“Those bases which do not dissociate completely in water weak bases.”

Weak bases partially ionize in water and their solutions to ions also contain unionized molecules.

Examples:

Some bases weak bases are given below:

 

Weak Base

Chemical Formula

 

Ammonium Hydroxide

NI-140H

 

Aluminum Hydroxide

_i__

Al(OH)3

 

Ferric Hydroxide

 

Fe(OH)3

 

Zinc hydroxide.

 

Zn(OH)2

. Explain self-ionization of water.

Ans. Self-ionization of water:

“The reaction, in which two water molecules produce ions, is called self-ionization or auto-ionization of water.

Explanation:

It is experimentally proved that water ionizes into hydronium ion(H30+)and hydroxide ions (OH-) to a very small extent.

During self-ionization of water two molecules of water react to produce hydronium ion (L130′) and hydroxide ion (OH-)

H2O (I + H20 (1) —0.1-130+ (aq) 01-1(AA)

In order to understand the concept of ionization of water, we take one molecule of water and its ionization at 25°C.

The equation for ionization of water is:

H2O H++ OH-

Equilibrium constant expression for this reaction is:

KC _. [H+][Airily

[H20]

K [H 20]-= [H+1[OH+]

Since the dissociation of water into ions is very small, the concentration of H2O remains constant and the above equation can be written as:

Kw t_ = r OH-1 where Kw = Kc [H, 0]

Dissociation constant of water Lisa„:

Kw is called dissociation constant or ionization constant of water. It is defined as “the product of molar concentration of W(H30+) and OW ions is called dissociation constant of water.” The value of Kw of water at 25°C is 1.0x 10.-

Kw = [H+1 [0/11= 1.0×10-14m2 eq.1

As [F11= [OH-]

Putting [OH-] = [H+] in eq.1 we get [H.] pry= 1.0×10 14m2

[HT = 1.0X10-14M2

[.111.]=1/1.0X10-14M2

Therefore [F14] = 1.0×10-7 M and [OH-] = 1.0×10-7M

KW = Lii+1 0H+1

c> Kw =p .0 y.10 – IP= 1 .0x10-14m2

10: What is meant by P”? Explain. PH:

Ans The acidity or basicity of a solution is expressed in term of PH Introduction:

Soren Peter Laurite Sorenson in 1909 suggested a simple number scale based on 1-1+ ion concentration to express the acidic or basic nature of the solution which is clod scale. The values ore this scale range from 0 to 14

Definition:

The logarithm of reciprocal of molar concentration of W ions is called PH.

Mathematically:

P”= log I

[H.]

PH = log1 – log [W] Q log — = log m – log n

RT

PH = 0 — log [H+] Q log 1= 0

P”=- log [W]

Therefore 13″ can also be defined as:

“The negative logarithm of molar concentration of H+ ions is called PH.” Meaning of p in PH:

P stands for potent (potential to be). Thus, PH means potential of H+ ions while it denotes negative log i.e. P = —log.

Comparison of PH values:

A solution having 13″ vale of 7 is neutral, less than 7 is acidic while a solution having PH value more than 7 is basic.

Whole number value of PH below 7 is ten times more acidic than the next higher value.

For example:

A PH of 2 is ten times more acidic than PH of 3 and 100times more acidic than a PH value of 4.

Experimental determination of P”:

Experimentally P” is determined by two methods:

By PH paper:

A rough value of PH is determined by using PH paper.

ii. By PH meter:

PH r dieter is an instrument which determines accurate value of PH.

11. Differentiate between PH and P°” scales. Ans. Difference between PH and P°H:

0.12. Prove that PH + P°H =14

The logarithm of reciprocal “The logarithm of reciprocal of molar concentration of H+, of molar concentration of ions is called PH. OH- ions is called P°H.

2

PH =

FDOH _ log 1

[OH I

p0H = log1 – log [OH1 Q logline = log m – long

P°H = 0-log [OH-] Q log1=0

= – log [OH-]

IH-1

PH = log1 – log [H+]

Qlogm =login-loge

PH = 0 – log [H+]

Q log1=0

P” = – log [H+1

P can also be defined as: Push can also be defined as:

The negative logarithm of “The negative logarithm of molar concentration of FL+ molar concentration of OH-ions is called PH.” ions is called P°”.”

Ans: As we know that:

Kw= [H-] 10H1= 1.0×10-14 or 10-‘4

L

Or [11±1 [OH-1=10-14

Taking -log on both sides:

-log [H+][0H1= -log10-‘4

-102; H-s-] 1+ [- log [OH 10-14 Q – log = -log 1//+1 = pH and – log OH-• = poll

Therefore PH +P°’ = – log10-14

PH +p0H =

– (-14) log10 Q log m” = n log m

PH +P°H = 141og 10 Q log 10=-1

PH +P°H = 14×1 = 14

Hence proved that,

+P°H. 14

Table. PH and Pcm values

Concentration of H + Values ions

1 or 10 10 7 14

10 __1 2 121 Strong acids

10__2 1 13

10__3 3__ 11__

106___________________6 8

107___________________7 7 Neutral

108___________________8 6

109___________________9

1010___________10 4 Weak bases

1011___________11 3__

1012___________12 21_

1013___________13 0

1014___________14_

Example 10.2:

Calculate the PH and P°H of 0.001M solution of nitric acid?

Given:

Molarity of nitric acid solution = 0.001M

Required:

To calculate the PH and P°H

Solution:

Chemical equation for ionization of nitric acid is:

HNO3_ H+

o.00im o.00im

Hydrogen ion concentration [H+]: 0.001M = 1–000 – 10-3M

Determination of P°H:

PH = – log [H+]

Putting the value of [H+] we get:

PH = – log10-3

13H = – (-3) log 10 Q log Inn = n log in

PH = 31og10

PH = 3×1 Q log10=1

PH = 3

Determination of P°”: We know that:

PH+ p0H = 14

p0H = _ pH

Putting the value of pH we get:

= 14-3 P°11 = 11

Result:

—137= 3, Pci” = 11

Examples 10.3:

Calculate the • P” and Pc)” of 0.01M potassium hydroxide (KOH) solution?

Given:

Concentration of KOH solution = 0.01M

Required:

To calculate the P” and P (:)”

Solution:

Chemical equation for ionization of potassium hydroxide is:

KOH ► K* + OH

0.01M 0.01M

Hydroxide ion concentration john- 1= 0.01M = 10-2M Determination of P°11:

p0H = log [01-11

Putting the value of [0111 we get: pon = log10-2

p0H = (-2) 10910

0102m = n log m

13°H = 2Iog 10

p0H =

Q log10=1

p0H = 2

Determination of P”: We know that:

PH+ P°” = 14 = 14 – Pc)”

Putting the value of Pc)” we get:

P”= 14-2 PH = 12

Result:

P°”= 2 and PH= 12

Q.13 Explain acidic, basic and neutral solutions?

Ans. Neutral Solution:

A solution having PH value of 7 is neutral solution. Neutral solution has equal concentration of H+ ions and OH- ions which is 1 XL 0-7M at 25°C. Acidic Solution:

A solution having PH value less than 7 is acidic solution. Acids increase the concentration of H+ ions thus its PH is decreased. Thus, in

Acidic solution the concentration of H- ions will be more than 1 x10-7M. Example:

A solution having concentration of H- ions 1 x10-4M is acidic because this concentration is greater than the concentration of H- ions in a neutral solution.

Basic Solution:

The solution having PH value greater than 7 is basic solution. Bases increase the concentration’ of OH- ions in aqueous solutions. Thus, its pH is increased.

Example:

A solution containing concentration of OH- ions.1×10-4M is basic because this concentration is greater than the concentration of Fr ions in a neutral solution.

Q.14 Explain the process of neutralization?

Ans. Neutralization:

“The reaction of an acid with a base to form salt and water is called neutralization reaction.”

Explanation with example:

For example, when HCI reacts with NaOH, NaCI and water are formed. HCI (aq) + Na0Hcaq) ► NaCI (aq) + H200)

Acid base salt water

In order to understand the process of neutralization, we need to write the acid, base and salt in their ionic forms.

H+ + + Na+ + + Cl- + H2O

In solution HCI exists as H+ and Cl-, and NaOH exists as Na+ and OH-. In neutralization H+ reacts with OH- to form water, leaving Na+ and CI- ions in the solution.

In the above equation Na+ and ions are present on both sides of

The equation and they have not reacted. They are called spectator ions. So the net reaction of neutralization is the reaction of H+ with OH- to form water as given below:

H+ + OH- ► H2O

There are equal numbers of H- and OK ions in equal molar solutions of HCI and NaOH both of which are fully converted to H20.

SI, Ms Notes 39 Acids. Base and Salts j

.15. What are salts explain with examples?

Ans. Salt:

The substance obtained (in addition to water) as a result of acid base reaction is called salt.” OR

“A class of solid crystalline ionic substances consisting of positive and negative ions, r: eerily good conductors in aqueous solution or in molten states are caked salts.

Composition of sat:

A salt consists of positive ions combined with negative ions. Positive ions come from a base while negative ions come from an acid i.e. In NaCI Na’ is from NaOH while Cr- is from HCI. The detail of combination of positive and negative ions is given below:

Monoatomic positive ion + monoatomic negative ions:

Examples of such salts are given NaCI. AgCI, and KCI, LiF. NaFetc Polyatomic positive ions + polyatomic negative ions:

Examples of such salts are (NH4)2CO3. NH4NO3. NH4HCO3 etc. Monoatomic positive ions + polyatomic negative ions:

Examples of such salts are Na2SO4. CaSO4. MgCO3 etc. Polyatomic positive ions + monoatomic negative ions:

Examples of such salts are NH, C1. NH4F. NI-14E3r. (NH4)2S etc. Examples of some salts:

Some exar^o es a-e given below.

i. Sodium chloride (NaC1)

ii. Sodium bicarbonate (NaHCO3)

iii. Calcium oxide (Ca0)

iv. Ammonium nitrate (NH4NO3) etc.

Q.16. How salts can be prepared?

Ans: Preparation of salts:

There are two types of salts

1. Soluble salts

2. Insoluble salts

Their preparations are given below:

Preparation of soluble salts:

They are prepared by the following methods:

I. By neutralization reaction:

One of the most important and common method of preparation of soluble salts is neutralization reaction. in which an acid reacted with a base to form salt and water:

NaOH + HCI NaCI + H2O

KOH + HNO3 KNO3 + H20

Base Acid salt water

ii. By the reaction of metal and acid (Direct displacement method): In this method hydrogen ion of an acid is replaced by an active metal like zinc, calcium, magnesium etc. to produce salt and hydrogen gas.

Zn + 2HCI ZnCl2 + H2

Mg + 2HCI MgCl2 + H2

Iii. By the Reaction of Acid and Metal Oxide:

Metallic oxides like calcium oxide, copper oxide etc. react with dilute acids to form salt and water.

Ca0 + H2SO4 CaSO4 + H2O

CuO + H2SO4 CaSO4 + H2O

Iv. By the reaction of acids with carbonates and bicarbonates: When an acid reacts with carbonate or bicarbonate it produces salts e.g.

Na2CO3 + 2HCI 2NaCI + CO2 + H2O

NaHCO3 + HCI NaCI + CO2 + H2O

2. Preparation of Insoluble Salts:

Insoluble salts are prepared by mixing the solutions of two soluble salts. In this reaction the two salts exchange their ions and form two new salts. One is the insoluble salt which is precipitated while the other salt remains dissolved in the solution.

AgNO3 (aq) +NaCl (aq) Ag Cl (ppo-NaNO3 (Ag)

NRC

Na2CO3 (aq) +CuSO4 CuCO3 (PPO+Na2SO4 caw

17 Describe the different types of salts in detail.

Ans. Types of salts:

There are three types of salts i.e. normal, acidic and basic salts their detail is given below:

i. Normal salts or neutral salts:

The salts formed when hydrogen atom of an acid is completely replaced by a metal ion or group of atoms behaving like metal ion are called normal salts. ‘OR

The salt which is formed by strong acid and strong bases is called neutral salt.

Examples:

NaOH + HCI > NaCI + H2O

KOH + HNO3–•KNO3 + H2O

Some other examples of normal salts are given below:

i. Potassium sulphates (K2SO4)

ii. Sodium phosphate (Na3PO4)

iii. Ammonium sulphates [(N1-14)2SO4]

iv. Sodium carbonate (Na2CO3)

ii. Acidic salts:

The salts formed when hydrogen atom of a polypro tic acid is partially replaced by a metal ion or group of atoms behaving like metal ion are called acidic salts. “OR

The salt which is formed by strong acid and weak base is called acidic salt.”

Acids which form acidic salts:

Acidic salts are formed by polypro tic or polybasic acids only e.g. H2SO4, H2003, H3PO4etc

Examples:

H2SO4 + KOH KHSO4 + H2O

H2003 + NaOH >NaHCO3 + H2O

Polypro tic acid base acidic salt

Some other examples of acidic salts are given below:

i. Ammonium bi phosphate [(NI-14)1-12PO4]

ii. Potassium bicarbonate (KHCO3)

iii. Lithium bisulphate (LiHSO4)

iv. Calcium bicarbonate [(Ca (HCO3)2] etc.

iii. Basic salts:

“The salts formed when hydroxide ion of a poly acid base is partially replaced by negative ions of acids are called basic saits. “OR

The salt which is formed by weak acid and strong base is called basic salt.”

Bases which form basic salts:

Basic salts are formed by poly acid bases only e.g. Ca (OH) 2, Mg (OH) 2, Al (OH) 3 etc.

Examples:

Ca (OH) 2 + HCI –*Ca (OH) CI + H2O

Mg (OH) 2 + HCI —>Mg (OH) C1 + H2O some other examples of basic salts are:

i. Lead monohydroxy chloride [Pb (OH) CI]

ii. Copper monohydroxy chloride [Cu (OH) CI]

iii. Aluminum dihydroxy fluoride [Al (OH) 2F]

iv. Barium monohydroxy fluoride [Ba (OH) F.]

18. Describe the uses of salts?

Ans. Uses of salts:

Salts have many different uses, ranging from household to big

Industries. Some important uses of different salts are given below:

1. Sodium chloride (NaCI):

i. It is daily used in our food to give it taste.

Iii.No industry it is used as raw material for the preparation of caustic soda, washing soda etc.

iii. It is also used in de-icing if road ways.

iv. It is also used for preserving food.

2. Calcium sulphates dehydrate CaSO4.2H201

i. It is also called gypsum and is used in the manufacture of plaster of Paris and cement.

1i. it is also used as fertilizer.

3. Sodium Sulphates Na2SO4:

It is used in the manufacture paper, glass and detergents etc.

4. Sodium carbonate (Na2CO3):

i. Anhydrous sodium carbonate (Na2CO2) is called soda asn while hydrated sodium carbonate (Na2CO3.10H20) is called washing soda.

ii. It is used as cleaning agent in laundries and as water softener.

iii. It is also used as raw material in the manufacture of glass. Iv.lt is also used in paper industry, leather industry and petroleum refining industry.

5. Sodium bicarbonate (NaHCO1

i. It is also called as baking soda because it is used in baking of cakes and other confectionaries.

ii. It is also used as antacids in medicines and in toothpastes.

6. Copper sul hate CuSO4.5H20 Blue vitriol):

i. It is used as electrolyte in copper electroplating process.

ii. It is also used to kill algae in water reservoirs ana in agriculture spray.

7. Klagnesiumsalt:

i. It is used as antacid and laxative in medicines.

ii. It is also used in dye industries.

8. Potash alum (K1SO4. Alz (S051. 24H20):

I. It is used for W8::er” p f c.-, atEcr -e7rove suspended impurities by a

Process called flocculation or coagulation.

Ii.lt is also used in textile industry since it causes dyes to adhere to the fabric.

iii. It is also used as blood coagulant in small injuries.

9. Calcium Carbonate (CaC0)

It is used in preparation of cement and ceramics industry.

10. Potassium Nitrate

It is used as a fertilizer and in the manufacture of flint glass.

word image 42

Multiple Choice Questions

Q.1: Select the suitable option:

i. According to Arrhenius concept, which of the following is not an acid?

A) HCI B) H2SO4 C) CO2 D) HNO3

Ii…AIC13 is an acid according to

A) Arrhenius B) Lowry and Bronsted C) Lewis D) All

iii. Which one of the following is a Lewis base?

A) HCI B) AlC13 C) BF3 D) F-

iv. Neutral solution has a pH value of

A) 3 B) 5 C) 7 D) 14

v. The pOH of 0.001 M solution of nitric acid i

A) 0.001 B) 10.0 C) 11 D) 14

vi. When a strong base and weak acid reacts, the only products are:

A) Neutral salt and water B) Basic salt and water

C) Acidic salt and water D) Acidic, Basic salt and water

vii. NH3 is a base according to

A) Arrhenius B) Lowry and Bronsted

C) Lewis D) Both B&C

viii. Which one of the following is a basic salt?

A) KCI B) NaCI C) Pb (OH) CI D) KHSO4

ix. The bases which are soluble in water are called

A) Acids B) Alkalis C) Salts D) KHSO4

x. The example of weak acid is

word image 43 A) HNO3 B) CH3COOH C) HCI D) H2SO

1. When a clear liquid is placed in a beaker. How can you identify it as an acid, base or neutral (water)?

Ans. Identification of a liquid to be acid, base or neutral:

A clear liquid in a beaker can be determined to be an acid, base or neutral by finding its PH value. PH value is finding by the following ways;

I. By Using PH paper:

A strip of pH paper will be dipped in the liquid. Its colour will change. This colour will be matched with colour bands having pH values from 0 to 14.

Ii. By Using PH meter:

It is a digital instrument which is dipped in the liquid. pH value is directly read from its LCD screen.

Q.2. Justify FL+ion as a Lewis acid?

Ans. FL+ ion As Lewis Acid:

According to Lewis concept;

Acid is a species which accept a pair of electrons. Since FL+ has shortage of two electrons. Therefore, it accepts a pair of electron when reacts with a species having lone pair of electrons or a species having negative charge like OH”.

Reactions:

i. H++ OW ► H2O

Acid Base In the above reaction H+ ion accept a pair of electron from oft ion, thus it is a Lewis acid.

ii. NH3 + H+ ► NH4

In the above reaction H+ ion accept a pair of electron from NH3, thus it is a Lewis acid

(Q.3. Distinguish strong acids from weak acids? Give two examples of each.

Ans: Differences between strong and weak acids:

Some differences between strong and weak acids are given in the

Table below: Strong Acid . Weak Acid

(i) “Those acids which “Those acids which partially

Almost completely ionize ionize in water are called

In aqueous solutions and weak acids.”

Give higher concentration

Of H+ ions are called

Strong acids

ii) The solution of strong The Solutions of weak acids

Acids contain ions and in addition to ions also

Almost no unionized contain unionized molecules.

Molecules are left.

Strong acia are strong Weak acids are weak

Electrolytes. Electrolytes.

(iv) Examples: Examples:

  1. Hydrochloric acid(HCI) a. Carbonic acid(H2CO3)
  2. Nitric acid(HNO3) b. Acetic acid(CH3COOH)

. Compare the physical properties of acids and bases.

Ans: For answer see Question no.2

. A carbonated drink has [H+] =3.2x1013M, classify the drink as neutral, acidic or basic with reason?

Ans. Classification of a substance as acidic, basic or neutral:

The acidic, basic or neutral nature of a substance depends upon it pH value.

i. If the pH value is 7 it neutral.

ii. If the pH vague is more than 7 it is basic.

iii. If the pH value is less than 7 it is acidic. So first we will find the pH value of given substance. As we know that;

Hydrogen ion concentration [H+] = 3.2X10-3M Determination of pH:

PH = – log [H+]

Putting the value of [H+] we get:

PH = – log 3.2×10-3

= – (log3.2 + log 10-3) Q log m x 11 = log al log n

= – (log3.2 + (-3log10)) Q logm” = n log m

PH = – (0.5051+ (-3×1) Q log10=1

PH = – (0.5051-3:

= – (-2.4949)

Ph. = 2.4949

Conclusion:

As the pH value less than 7 therefore the given carbonated drink Is civic due to higher concentration of H’ ions.

6: Write the chemical name of an acid present in the following:

(d) Sour milk

(a) Apple (b) Grape Juice (c) Lemon Juice Substance Name Acid Present

  1. Apple Mali° Acid
  2. Grape Juice

Tartaric Acid

  1. Lemon Juice Citric Acid
  2. I Sour Milk j Lactic Acid

7. What determines the strength of a base? Give one example of each solution that is strongly and weakly basic.

Ans. Determination of strength of a base:

The extent to which a base ionizes in aqueous solution determines the strength of a base. If the base ionize completely then it is called strong base and if the base ionizes partially it is called weak base.

One example of strongly basic solution”

The solution of sodium hydroxide (NaOH) is strongly basic. One example of weakly basic solution” The solution of ammonium hydroxide (NH4OH) is weakly basic.

.8: Calculate the PH and P°H of 0.5M solution of HCI.(ph. 0.301, P0.13.69)

Given:

Molarity of hydrochloric acid (HCI) solution = 0.5M

Required:

To calculate the PH and p01-1

Solution:

Chemical equation for ionization of nitric acid is:

HCI H+ + CI-

0.5M 0.5M

Hydrogen ion concentration [H+] = 0.5M = 5x10_1 M Determination of PH:

P = —tog [H

Putting the value of [H1 we get:

= — log [5×10-1]

„ PH = — (log5+loo1071) 0102, Mn, — log m ÷ log n

PH= —log5 —Iog1071

= — (0.6989) — (-1) log10 Q log m” = n login

PH = —0.6989+11°g 1 0

=-0.6989+1×1 Q iogl0=1

= —0.6989+1

PH= 0, 3011

Determination of pOH: We know that:

P-H POH = 14 P°H = 14 – pH

Putting the value of pH we get:

=> P°H = 14-0.3011

P°H = 13.6989

Result:

Pc)” = 13.6989and PH= 0.3011

Calculate the Pc’ of 0.005M LSO4. (P = 11.699)

Given:

Molarity of sulphuric acid (H2SO4) solution = 0.005M Required:

To calculate the Pcr”

Solution:

Chemical equation for ionization of sulphuric acid is: H2SO4 (aq) 2H+ + Se; =

0.005M 2×0.005M

Hydrogen ion concentration in’; = 2×0.005M

= 0.010M

= 1×10-2M or 10-2M

For finding P°” first we will find P” as we are given the concentration of 1-1+ ions.

Determination of P”:

13″ = —log [H+]

Putting the value of [H+1 we get:

= — log [10-2]

H

= — (-2Iog 10) Q log 11111 = log m + log n

PH = — (-2) (1) Q log10=1

PH = 2

Determination of polio:

We know that:

PH + pOH = 14

P°F1= 14 –

Putting the value of PH we get:

Pc)” = 14-2

p0H = 12

Result:

r= 2

10: Calculate the PH of 0.2M solution of NaOH. (PH=13.30)

Given:

Molarity of NaOH solution = 0.2M

Required:

To calculate the Pr.

Solution:

Chemical equation for ionization of NaOH is:

NaOH Na+ +

0.2M 0.2M

Hydroxyl ion concentration [OH] = 0.2M

= 2×10-1M

For finding PH first we will find OH- ions.

Determination of P°H:

P°H = -log [OH-]

Putting the value of [OH-] we get:

p0H = log [2 x10-1

– Ho =_. 4n

(10gZ + log Q log mn = login -4- log n

Hr-.0 =

– (log2 + (-1) log 1 0) Q log INH login

= ..(1092

(1)(1)) Q log 10= 1

 P°H = – (0.3010 – 1)

= (-0.699)

 P°H = 0.699

Determination of PH:

We know that:

PH 4. p0H =

PH = 14 – P°H

Putting the value of P°H we get:

= 14 – 0.699

PH = 13.301

Result:

PH= 13.301

What is salt?

Ans: For answer see Question no.15

Write down the different types of salts with examples?

Ans: For answer see Question no.17

Define the auto- ionization of water. How can you find the PH of water?

Ans: For auto-ionization see Question no.9

I”indinc~the PH of falter:

The pH value of water can be found by two ways:

i. Mathematically

ii. Experimentally

i. Mathematically:

Mathematically the PH of water can be found by the following formula; PH = – log [H+]

For example the concentration of H+ ions in pure water is 10-7M

PH 7(1)

PH = 7

ii. Experimentally:

Experimentally PH is determined by two methods:

A. By PH paper:

A rough value of PH is determined by using P paper.

B. By PH meter:

P meter. Is an instrument whydah determines accurate value of PH. \kitiliKy some acids are called monocratic. Diprotic and pPlyprotic acids. Explain your answer with suitable examples.

Ans For answer see Question no.5

Discuss the concept of Lewis acids and bases with ‘examples.

Ans: sees Question no.3

The Bronsted-Lowery definition of acids and bases. Write Equations that explain the definition.

Ans: For answer see Question•no.3

Q 4.Below is two equations showing how two alkalis react with water.

Na0 H q) H 2 0 ( ) N a+ (aq) + 0 H (a)

NH3 (3,) + H20 (l) r NH4 (aq) + 01-1-(aq)

. Name both the alkalis.

Ans (a)

Alkali Formula
NaOH

 

Name Sodium Hydroxide Ammonia

 
  
  

NH3

   

Which is classified as weak alkali and why?

Ans. Weak Alkali in the Given Examples:

NH3 is a weak alkali

Reason:

Weak alkali is that alkaP which partially ionizes in water, Since, NH3 partial i: e in water. Therefore, it is a weak alkali.

What is the likely ri.4 of each alkali?

Ans. PH of the Given Alkalis:

The PH of NaOH is almost 14 while that of NH3 is about 9.

(A rite the balanced neutralization reaction of ,

(i) Strong acid and strong base

(ii) Strong acid and weak base

(iii) Weak acid and strong base

(iv) Weak acid and weak base. Ans: i.Stronq Acid and Strom g Base Reaction:

NaOH 4- !-420

Strom base Strong Acid and Weak Base Reaction:

Al (OH) 3 + 3HCI > AlC13 + 3H20

Weak base strong acid

Iii.Weak Acid and Strong Base Reaction:

H2003 + NaOH > NaHCO3 + H2O

Weak acid strong base

Iv.Weak Acid and Weak Base Reaction:

3H2CO3+ 2A1 (OH) 3 A1:1CO3)? 6H70

Weak acid weak base

Define PH and P°H?

Ans: See answer of Q No 11

6. (According to your understanding which one of the three acid definitions is the broadest? Explain.

Ans: Three Definitions of Acid:

Type Of Concept

Acid

Arrhenius

Freon producer in water.

Bronsted-Lowry

Proton(H+) donor

Lewis

Electron pair acceptor

Broadest definition of acid:

Among the three definitions of acid, the broadest is the Lewis concept.

Explanation:

The Arrhenius concept limits the acids to aqueous medium which Cannot explain the acidic behavior of acids in non-aqueous medium.

Similarly, the Bronsted-Lowry concept restricts acids to protons which cannot explain the behavior of acids having no protons like AlC13, BF3 etc.

The Lewis concept is a broadest of all the above mentioned concepts because it completely explains the acids definitions of Arrhenius and Bronsted-Lowry concepts. But they don’t explain the Acid definition of Lewis concept.

Example:

For example BF3 is a Lewis acid: it cannot be explained to be an acid on the basis of Arrhenius concept because it does not produce hydrogen ion in aqueous solution. Similarly, BF3 cannot be explained, to be an acid, on the basis of Bronsted-Lowry concept because it does not donate proton. However, it can be explained, to be an acid, on the basis of Lewis concept, to be an acid as it accepts electron pair.

Write the uses of any three salts.

Ans: For answer see Question no 18

Additional Multiple Choice Questions

1. According to Bronsted, acids are:

(a) Proton donor (b) Proton acceptor.

(c) Electron donor. (d) Electron acceptor.

2. NH3 is

(a) Acid (b) Base. (c) Salt. (d) Buffer solution.

3. Neutral solution has a PH value:

(a) 3. (b) 5 . (c) 7 (d) 14.

4. Lower the PH value will be an acid.

(a) Weaker (b) Stronger (c) Neutral (d) Alkaline

5. Salts are compounds.

(a) Acidic. (b) Basic. (c) Amphoteric. (d) Neutral.

6. KHSO4 is a salt.

(a) Basic. (b) Acidic (c) Neutral. (d) Amphoteric

7. Citrus fruits contain acid.

(a) HCI. (b) H2SO4. (c) HNO3. (d)CH3COOH.

8. HCI is present in

(a)Stomach (b) Liver (c) Mouth. (d) Large intestine.

9. For washing purposes base is used.

(a)Na2CO3.10H20. (b) NaHCO3. (c) Ca (OH) 2. (d)Mg (OH)2

10. According to Lewis concept acids are

(a)Electron pair acceptors. (b) Electron pair donors.

(c) H+ producers. (d) Producers.

11. In Lewis concept acid. Base form bond.

(a)Covalent. (b) Coordinate covalent.

(c) Ionic (d) Hydrogen bonding.

12. Compounds having less than eight electrons in valence shell of central atom and positive ions act as

(a)Lewis acids (b) Lewis base

(c) Arrhenius acid (d) Arrhenius base.

13. Compounds having one pair of electrons in the valence shell or negatively charged ions can donate electron pair and behave as —

(a)Lewis bases (b) Lewis acid

(c) Bronsted acid (d) Bronsted base.

. In soda water acid is present.

(a)H2SO4. (b) H2CO3 HNO3 (d)

15. For soap making and for drain opening is used

(a)NaOH (b) Na2C0: (c) NaHCO3 (d) Na2SO4.

16. Is used as antacid to neutralize excess of stomach acid.

(a)Mg (OH) 2 (b) NaOH (c) Ca (OH) 2 (C) KOH

17. In water the concentration 0′ H O` and OH- is always “x” (:- at temperature

(a) 30°c (b) 402c 25°c (d) 20:q.

18. Acid in stomach plays a role in the digestion of

(a)Protein (b) carbohydrates (c) fats (d) vitamins.

19. PH and P°H scales were introduced by in 1909.

(a)Sorenson (b) Priestly (c) Dolton (d) Lewis.

20. The measures acidity and basicity of a solution.

(A) Indicator (b) PH (c) litmus (d) Baeyer’s reagent.

21. The term acid is derived from—-word.

(a) English (b) Greek (c) Latin (d) Arabic

22. The sum of PH and P°H is equal to —-. .

(a) 7 (b) 10 types. (c) 12 (d) 14.

23. Salts are

(a) Two (b) three (c) four (d) five.

24. NH3 is

(a) Acid (b) base (c) salt (d) buffer

25. The conjugate acid of water is

(a) H304 (b) OH- (c) HOH 1d) none o{ these.

26. Which one of the following is a Lewis base?

(a) NH4OH (b) NH3 (c) CaO (d) NaOH

27. Which one of the following is an act’s salt—-.

(a) NaCI (b) Na2SO4 :c) NaHSO4 (d) NH4Cl.

28. Which one of the following is not a strong acid?

(a) CH3COOH (b) H2S0. I: c) HNO3 (d) HCI.

29. Which one of these acids is moncorott7?

(a) H2SO4 (b) H3PO4 (c) CH3COOH (d) None of these.

30. The chemical formula of baking soda

(a)Na2CO3 (b) NaHCO3 V (c) NaOH (d) Na2SO4.

31. Which one of the following is pol V-erotic acid%

(a) HCI (b) CH3COOH (c) none o= these.

1 thought on “Class 10th Chemistry Notes Chapter 2 ACIDS, BASE AND SALTS”

  1. Pingback: CLASS 9th MCQS CHAPTER 1 HISTORY AND NATURE OF SCIENCE - Daraz 24

Leave a Reply

Scroll to Top
%d bloggers like this: