CLASS 11 chemistry ch 7

CLASS 11 chemistry chapter 7

Equilibrium Constant KP Formula Chemical Ionic Consumer

Equilibrium Constant KP Formula Chemical 

Ionic Consumer in PDF

  ➣ Equilibrium state- When rate of formation of a product in a process is in competition with rate of formation of reactants, the state is then named as “Equilibrium state”.

➣  Equilibrium in physical processes:  

➣ Law of chemical equilibrium: At a given temperature, the product 

of concentrations of the reaction products raised to the respective stoichiometric coefficient in the balanced chemicalequation divided by the product ofconcentrations of the reactants raised totheir individual stoichiometric coefficientshas a constant value. This is known asthe Equilibrium Law or Law of Chemical Equilibrium.

aA +bBcC + dD  

Kc =[C]c [D]d[A]a [B]b  

Chemical equation      Equilibrium constant

aA + b Bc C + D K)

cC + d Da A + b B K' c=(1/Kc

na A + nb B ncC + ndD      K"" c= (Kcn)

Concentrations or partial pressure of pure solids or liquids do not appear in the expression of the equilibrium constant. In the reaction, KcAg2O(s) + 2HNO3M(aq) 2AgNO3 (aq)+H2O(l)          

➣  If Qc >Kc, the reaction will proceed in the direction of reactants (reverse 

reaction).If Qc <Kc, the reaction will proceed in the direction of the products (forward reaction)

➣  Kp is equilibrium constant in terms of partial pressure of gaseous reactants and products.

➣  Kc  is  equilibrium  constant  in  terms  of  molar  concentration  of  gaseous reactants and products

➣ Kp =Kc (RT)∆n here R is gas constant, T is temperature at which theprocess is carried out &∆n is no. of moles of gaseous product minus no. of moles of gaseous reactants.

➣  If Kc> 103;     Kc is very high i.e. the reaction proceeds nearly to completion.

➣  If Kc<103;     Kc is very small i.e. the reaction proceeds rarely.

➣ If Kcis ranging in the range of 103 to 10-3;  i.e. reactants and products are just in equilibrium.

➣ ΔGo = – RT lnK     or ΔGo = – 2.303RT log K

➣ Factors affecting equilibrium constant :- temperature, pressure, catalyst and molar concentration of reactants and products.

➣ L e Chate lie r ’s   pr i nc i ple  :-  It  states that  a change in  any  of  the  factors that determine the equilibrium conditions of a system will cause the system to change in such a manner so as to reduce or toc ounteract the effect of the change.

➣ Arrhenius acids are the substances that ionize in water to form H+ .

➣ Arrhenius bases are the substances that ionize in water to form OH-.

➣  Lewis acids are lone pair (of e-) accepters while Lewis bases are lone pair donators.

➣ Proton donor are acids while proton accepters are bases(Bronsted-Lowry concept).

➣ The acid-base pair thatdiffers only by one proton is called a conjugateacid- base pair. IfBrönsted acid is a strong acid then itsconjugate base is a weak base and viceversa.

➣ Ionic product of water.Kw = [H+][OH–] 

➣ pH = -log [H+] ; here[H+] is molar concentration of hydrogen ion. 

➣pH + pOH =14

➣pKa + pKb =14

➣Ka x Kb = Kw = ionic product of water=1 x 10-14

➣  Buffer solution  :The solutions which resist change in pH on dilution or with the addition of small amounts of acid or alkali are called Buffer Solutions.

➣common ion effect: It can be defined as a shift in equilibrium on adding a substance  that  provides  more  of  an  ionic  species  already  present  in  the dissociation equilibrium. 

➣ Hydrolysis of Salts: process of interaction between water and cations an ions or both of salts is call edhydrolysis. 

➣ The cations (e.g., Na+, K+,Ca2+, Ba2+, etc.) of strong bases and anions(e.g., Cl–, Br–, NO3–, ClO4– etc.) of strong acids simply get hydrated but do not hydrolyse, and therefore the solutions of salts formed from strong acids and bases are neutral i.e., theirpH is 7. 

➣ Salts of weak acid and strong base e.g., CH3COON a are basic in nature. 

➣ Salts of strong acid and weak base e.g.,NH4Cl, are acidic 

➣ Salts of weak acid and weak base, e.g.,CH3COONH4. The pH is determined by the formula    pH = 7 + ½ (pKa – pKb) 

➣ Solubility  product-  product  of  the  molar  concentrations  of  the  ions  in  a saturated solution, each concentration term raised to the power equal to the no. of ions produced.

Physical and chemical processes

 Physical processes include changes that affect only the physical properties of the material, which are subject to change, but have no effect on the chemical composition and properties.

 Chemical processes include changes in chemical composition and properties.  When a chemical change occurs, we can say that a chemical reaction has taken place.

 Types of chemical reactions:

 1. Complicated reactions

 In such reactions, two or more substances combine to form a single compound.

 For example,

 2 mg + O2 → 2 mg

 2. Decomposition reactions

 In these reactions.  The composition decomposes to produce two or more different substances.

 For example, PCI5 ⇔ PCI3 + CI2

 Food assimilation is also a glycemic reaction.

 [Mal ether dissolution is called thermal decomposition, and male light dissolution is called photolysis.

 3. Displacement reactions

 These reactions include one element or group displacement.  These are ineffective reactions, reducing, for example,

 Zn (s) + H2SO4:

 4. Interactions of double displacement or shift

 In this.  Interaction Two compounds interact to form two new compounds, and there is no change in the state of oxidation, for example, precipitation reactions, equation, reactions.

 AgNO3 (aq) + NaCI (aq) → AgCl (s) + NaNO3 (aq)

 Balance sheet

 Under certain circumstances, if the reversible or chemical reaction is carried out in a closed container, the stability is observed in some observed properties, such as color density, pressure and density.  This state is called the state of equilibrium.

 The rest can be classified as follows:

 Physical balance

 A balance that is created in physical processes, such as the evaporation of water, the solubility of solids, the dissolution of a solution, etc., is called physical equilibrium, for example, ice water.

 In balance

 Snow melting rate = water cooling rate

 Chemical equilibrium

 If the reverse reaction takes place in a closed container, it reaches a stage where the reaction rate is equal to the reaction rate.  Chemical equilibrium is compensated.  In balance

 Transmission reaction speed = reverse response speed

 Properties of chemical equilibrium

 1. Balance can be achieved on both sides.

 2. Equilibrium is dynamic in nature, that is, when the equilibrium ceases.

 3. There is no change in the concentration of different species when balancing.

 4. The equilibrium condition remains unaffected by the presence of a catalyst.  The catalyst helps to balance quickly.

 6. The observed physical properties of the process become fixed.

 Mass labor legislation

 Gդldberg and Weig note that the rate of a chemical reaction is directly proportional to the product of the active masses of the reagents.  For a general response

 Where kf and kb are speed constants.

 The active mass of solid and pure liquids is taken into account in the heterogeneous balance

 In balance

 Transmission reaction speed = reverse response speed

 Kc is called stable equilibrium.

 Use partial pressure instead of focusing

 For gas reactions, partial pressures are used appropriately, as at any stable temperature the partial pressure is directly proportional to the concentration.  For general gas reaction

 The relationship between Kc and Kc

 Where = ng = mol products: reactive moles (gas only)

 The relationship between Kc and Kp for different types of reactions

 (I) When Δng = 0, Kp = Kc

 (ii) when Δng = + ve, Kp> Kc

 (iii) at = ng = -ve, Kp <Kc:

 Kp և Kc points

 (I) points Kp = (atm) Δng

 (ii) unit Kc = (mol L-1) Δng

 Stable equilibrium properties Kp or Kc

 1. It has a special value for each chemical reaction at a specific temperature.

 2. The higher the value of Kc or Kp, the more complete the reaction will be, ie Kc <1 indicates a lower concentration of the product than the reagents.

 K ≥ 103 indicates that the response is complete, և K ≤ 10-3 indicates that the response does not continue at all.

 3:When the reaction can be expressed as sum of two other reactions, the Kc of overall reaction is equal to the product of equilibrium constants of individual reactions.

4. The equilibrium constant is independent of initial concentrations of reactants.

5. Equilibrium constant is independent of presence of catalyst.

6. Kc for backward reaction is inverse of Kc for forward reaction.

7. If an equation is multiplied by n, the K becomes Kn, and if it is divided by m, the k becomes m √k.

8. In equilibrium constant expression if activities are used in places of molar concentration, h becomes dimensionless.

Types of Equilibrium

Homogeneous Equilibrium

In homogeneous equilibrium, the reactants and products arc present in the same phase or physical suite (gaseous or liquid).

2SO2(g) + O2(g) ⇔ 2SO3(g)

Heterogeneous Equilibrium

In heterogeneous equilibrium the reactants and products are present in two or more physical states or phases.

3Fe(s) + 4H2O(g) ⇔ Fe3O4(s) + 4H2(g)

Reaction Quotient

For any reversible reaction at any stage other than equilibrium, the ratio of the molar concentrations of the products to that of the reactants. where each concentration term is raised to the power equal to the stoichiometric coefficient to the substance concerned, is called the reaction quotient, Qc.

For a general reaction

aA + bB ⇔ cC + dD

which is not at equilibrium,

Qc = [C]c + [D]d / [A]a [B]b

If

(i) Qc > Kc, the value of Qc will tend to decrease to reach the value of Kc (towards equilibrium) and the reaction will proceed in the reverse direction.

(ii) Qc < Kc it will lend to increase and the reaction will proceed in the forward direction.

(ii) Qc = Kc, the reaction is at equilibrium.

Le – Chatelier’s Principle

There are three main factors which affect the state of equilibrium.

They are

concentration

temperature

pressure.

Le – Chatelier’s principle states that if a system at equilibrium is subjected to a change in concentration. pressure or temperature. the equilibrium equilibrium change.

Effect of Change of Concentration

If at equilibrium the concentration of one of the reactants is increased. the equilibrium will shift in the forward direction and vice-versa.

Effect of Change in Pressure

No effect of pressure on equilibria having same moles of reactants and products. e.g., N2 + O2 ⇔ 2NO.

When there is change in the number of moles, the equilibrium will shift in the direction having smaller number of moles when the pressure is increased and vice-versa, e.g.,

N2 + 3H2 ⇔ 2NH3 [High p. high yield of NH3]

Effect of Temperature

When process is exothermic, low temperature favours the forward reaction. When process is endothermic. high temperature favours the formation of products.

Effect of Addition of Inert Gas

(i) Addition of inert gas at constant pressure At constant pressure. if an inert gas is added. it will increase the volume of the system. Therefore. the equilibrium will shift in a direction in which there is an increase in the number of moles of gases.

(ii) Addition of inert gas at constant volume If keeping volume of the system constant, an inert gas is added. the relative molar concentration of the substance will not change. Hence. the equilibrium position of the reaction remains unaffected.

Effect of Catalyst

The presence of catalyst does not change the position of equilibrium. It simply fastens the attainment of equilibrium.

Le-Chatelier’s Principle Applicable to Physical Equilibrium

(i) Effect of pressure on solubility The increased pressure, will increase the solubility of gas and vice-versa.

(ii) Effect of temperature on solubility  Some substances dissolve with the absorption of heat. Solubility of such substances will increase with increase of temperature and vice-versa, e.g., dissolution of NH4CI, KCI, KNO3, etc. The dissolution of calcium acetate and calcium hydroxide is exothermic, so their solubility is lowered at higher temperature.

(iii) Effect of pressure on the melting point of ice

Ice ⇔Ice and liquid water

 Ice is larger than liquid water, so increasing pressure will cause the ice to melt, according to Le-Chatelier.

 Favorable conditions for some chemical equilibrium to obtain higher product yield.

 Calculate the density measurement (α) by measuring the density

 α = d - d / d

 Where D = theoretical vapor density

 D = the observed vapor density

 Now the molecular mass = 2 * VD

 A = Mc - Mo / Mo:

 Where, Mc = calculated molecular weight

 Mo = observed molecular weight

 All chemistry classes for the eleventh grade.  Physical writing