10th Class Chapter 1 Chemistry Long Questions

Part (A)

Salt:

Salts are ionic compound generally formed by the neutralization of an of acid with the base.

Types of salts:

Normal salta Acidic salts

Basic salts Double salts

Mixed salts Complex salts

Normal Salts:

A salt form by the complete replacement of innizable -H- inn of an acid by a positive metal ion or NH4+ ion is called normal or neutral or litmus.

Chemical reaction:

HCL +KOH _________ KCL+H2O

H² SO4 _________ ZnSO4+H2O

H3PO4+3NaOh _________ Na3PO4+3H2O

HNO3 +NH4OH _________ NH4NO³ +H2O

Acidic salts:

These are formed by partical replacement of a replaceable H+ ion of an acid by a positive metal ion .

Reaction:

H²O4+KOH __________ KCL+H2O

H3PO4+ NaOH ___________ NaH2PO4+H2O

These salts turn blue litmus red.Acidic salts react with bases to form normal salts.

KHSO4+KOH ___________ K2 SO4+H2O

Nah2+ PO4+2NaOH ___________ Na3PO4+2H2O

Basic salts:

Basic salts are formed by the incomplete neutralization of a polyhydroxy base by an acid.

Reaction:

AL (OH)3 + HCL __________ AL ( OH )2 CL+H2O

Pb (OH)2+ CH3COOH __________ PNb(OH) CH3COO+H2O

Zn (OH)2+HNO3 __________ Zn (OH) NO3+H2O

Chemical reaction:

These salts further react with acids to form normal salts.

AL (OH)2 CL+HCL _________ AL(OH)2 CL+H2O

AL(OH) CL2+HCL _________ ALCL3+H2O

Pb (OH)CH3COO+CH3COOH _________ Pb(CH3COO)+H2O

Zn(OH) NO3+HNO3 _________ Zn (NO3)2+H2O

Part (B)

Aluminium+Hydrochloride:

Aluminium+ hydrochloride________ Aluminium chloride+hydrogen

2AL+6HC ___________ 2ALCL3+3H2

Copper oxide+sulphuric acid:

Copper oxide+ sulphuric acid _________ copper sulphate +water

CuO+H2SO4 ___________ Cu SO4+H2O

Ferric Chloride + Sodium hydroxide:

Ferric+sodium hydroxide ___________ ferric hydroxide+sodium chloride

FeCL3+3NaOH ___________ Fe (OH)3+3NaCL

Part (A)

PH of Solution:

The negative larger then of the hydrogen ion concentration of a solution is called Ph.’’mathemat

Ically, ph cn be written as

Ph= log [H+]

Ph Scale:

With reference to equation ph= log [H+] a scale developed according to moral concentration of hydrogen ion [H+] that is called ph scale (or)

The scale on which the degree of acidity or alkalinity of an equeous solution is measured is called the ph scale.

Ph=-log[1.0*10-7]=7

Poh=-log[1.0*10-7]

Ph+poh =14

Uses of ph:

· It is used to determine acidic or basic nature of a solution.

· It is used to produce medicines culture at a microbiological particular, concentration of H+ ion.

· It is used to prepare solutions of required concentration necessary for certain biological reactions.

Part (B)

Indicators:

Indicators are the organic compounds. These compounds indicators the completion of a in titration by the change in its colour.These help in determining the acidic, basic and neutral nature of solution.

Explanation:

Indicators have different colours in acidic and alkaline solutions. There are different types of indicators.

Some of indicators are given below .

Litmus , Phenolphthalein, Methyl orange

Litmus:

Blue litmus turns into red in acidic solution.

Red litmus turns into blue in alkaline solution.

Phenolphthalein:

It is colourless in strongly acidic solution.

It is red in strongly alkaline solution.

It changes colour at a ph about 9.

Phenalphthalien is colourless in solution with ph less then 9.

Mathyl orange:

It gives red colour at ph 4.

It gives yellow colour from ph 4.

Few commonly used indicators in titration are given tables below

Direction of chemical reaction at any particular moment can be predict knowing the numerical values of equilibrium constant of a chemical reaction and comparing this with reaction quotient.

The rate of reaction is directly proportional to the active mass of a substance generally active mass is concentration having units of mole dm-3 expressed as square brackets[ ].

When the rate of forward reaction takes place at the rate of reverse reaction the composition of reaction mixture remains constant it is called chemical equilibrium state.

If a reversible reaction is allowed to continue for considerable time without changing the conditions and rates of forward reaction and rate of reverse reaction becomes equal but take place in opposite directions this is called dynamic equilibrium.

The large numerical value of Kc indicates that at equilibrium position the reaction mixture consists of almost all products and reactions are negligible.

2CO+O2_________2CO2

Kc = 2.2*10/22

It slows down gradually it takes place from loft to right.

The reactions in which products do not recombine to form reactants are called irreversible reations.

For example: 2H2+O2________-2H2O

The reactions in which products can recombine to form reactions are called reversible reactions?

For example:

H2+I2_____2HI , f2+3H2_____ 2NH3

Nitrogen can be used to replace air and eliminate oxidation of materials it most important use is in creating ammonia which turn is used to make fertilizers and explosives.

If the value of forward becomes equal to reverse the reaction is said to in equilibrium state thus QC=Kc such reactions have comparable amounts of reactants and products at equilibrium position another indication is free energy change is zero.

The state at which reaction does not stop only the rate of forward and reverse reactions become equal to each other but takes place in opposite direction it is called dynamic equilibrium state.

At equilibrium state reaction does not stop because forward and reverse reactions keep on taking place at the same rate but in opposite direction.

The reaction for synthesis of ammonia is as;

N23H2_____2NH3

Rf= Kf [N] [H2]3

Rf = Kr [ NH3]2

The expression for equilibrium constant of reaction is :

Kc = [NH3]2/[N2] [H2]3

Equilibrium constant is a ratio of the product of concentration of products raised to the power of coeffient to the products of concentration of reactants raised to the power of coefficient as expressed in the balanced chemical equation.products of concentration of products

Kc = raised to the power of coefficients ,Products of concentration and reactants raised to the power of coefficients.

Hydrocholoric acid ionizes in equeous solution as :

HCL______ H+CL-

Kc = [H+] [ CL-]/ [ HCL]

Accordnig to this law the rate of which a substance reacts is directly proportional to the product active masses of the reacting substances.

An equilibrium is achievable only in closed system an equilibrium state is attainable from either way i.e starting from reactant on form products.

If reaction quotient qc is large than equilibrium the reaction will go from right to left .

(Qc/ large) reverse (kc /small)

Oxygen is used to prepare sulphur dioxide sulphur dioxide is used in preparation of sulphur acid ( H2SO4)

Active mass is considered molar concentration it has a unit of mole dm-3 and expressed as square brackets [ ]

The major components of atmosphere are nitrogen and oxygen gases both of these gases constitute 99% of the atmosphere.

The concentration of specie at equilibrium stage attain the same values whether we start the reaction in the vessel in the forward direction or backward direction.

There are following certain reasons of failure of reaction reaction is reversible so products recombine to form reactants and dynamic equilibrium is established reaction condition like temperature pressure and catalyst are not satisfied .

These reactions that have large kc,value proceed almost forward so required to attain equilibrium.