Class 12 Chemistry - Chapter Surface Chemistry NCERT Solutions | What role does adsorption play in hetero
What role does adsorption play in heterogeneous catalysis?
The phenomenon of concentration of molecules of a gas or liquid at a solid surface is called adsorption.
Heterogenous catalysis is a catalysis in which the catalyst is in different physical phase from the reactant. The most important of such reactions are those in which the reactants are in the gas phase while the catalyst is a solid.
This heterogeneous catalytic action can be explained in terms of the adsorption theory. The mechanism of catalysis involves the following steps:
(i) Adsorption of reactant molecules on the catalyst surface.
(ii) Occurrence of a chemical reaction through the formation of an intermediate.
(iii) De-sorption of products from the catalyst surface.
(iv) Diffusion of products away from the catalyst surface.
(v) Diffusion of reactants to the surface of the catalyst.
The reaction occurs by the contact of reactants with the catalyst surface.The molecule of reactant (gas) are adsorbed at the catalyst surface where they form an ‘adsorption complex’. The catalyst surface behave like the surface molecules of a liquid and are not surrounded by atoms or molecules of their kind. Therefore, they have unbalanced or residual attractive forces (Vander waal’s forces) on the surface which can hold adsorbate particles.As the concentration of reactants on the surface of the catalyst increases, the rate of reaction also increases. In such reactions, the products have very less affinity for the catalyst and are quickly desorbed, thereby making the surface free for other reactants.
More Questions From Class 12 Chemistry - Chapter Surface Chemistry
- Q:-
Explain what is observed
(i) When a beam of light is passed through a colloidal sol.
(ii) An electrolyte, NaCl is added to hydrated ferric oxide sol.
(iii) Electric current is passed through a colloidal sol?
- Q:-
Why is adsorption always exothermic?
- Q:-
What do you mean by activity and selectivity of catalysts?
- Q:-
What modification can you suggest in the Hardy-Schulze law?
- Q:-
Explain the following terms:
(i) Electrophoresis
(ii) Coagulation
(iii) Dialysis
(iv) Tyndall effect.
- Q:-
What is an adsorption isotherm? Describe Freundlich adsorption isotherm.
- Q:-
Explain the terms with suitable examples:
(i) Alcosol
(ii) Aerosol
(iii) Hydrosol
- Q:-
How are colloids classified on the basis of
(i) Physical states of components
(ii) Nature of dispersion medium and
(iii) Interaction between dispersed phase and dispersion medium?
- Q:-
Discuss the effect of pressure and temperature on the adsorption of gases on solids.
- Q:-
Why does physisorption decrease with the increase of temperature
Popular Questions of Class 12 Chemistry
- Q:-
For the reaction R → P, the concentration of a reactant changes from 0.03 M to 0.02 M in 25 minutes. Calculate the average rate of reaction using units of time both in minutes and seconds.
- Q:-
Write the formulas for the following coordination compounds:
(i) Tetraamminediaquacobalt (III) chloride
(ii) Potassium tetracyanonickelate(II)
(iii) Tris(ethane-1,2-diamine) chromium(III) chloride
(iv) Amminebromidochloridonitrito-N-platinate(II)
(v) Dichloridobis(ethane-1,2-diamine)platinum(IV) nitrate
(vi) Iron(III) hexacyanoferrate(II)
- Q:-
(i) Write structures of different isomeric amines corresponding to the molecular formula, C4H11N
(ii) Write IUPAC names of all the isomers.
(iii) What type of isomerism is exhibited by different pairs of amines?
- Q:-
Why are solids rigid?
- Q:-
Write the structures of the following compounds.
(i) α-Methoxypropionaldehyde
(ii) 3-Hydroxybutanal
(iii) 2-Hydroxycyclopentane carbaldehyde
(iv) 4-Oxopentanal
(v) Di-sec-butyl ketone
(vi) 4-Fluoroacetophenone
- Q:-
Which of the ores mentioned in Table 6.1 can be concentrated by magnetic separation method?
- Q:-
Why are pentahalides more covalent than trihalides?
- Q:-
Silver atom has completely filled d orbitals (4d10) in its ground state. How can you say that it is a transition element?
- Q:-
Glucose or sucrose are soluble in water but cyclohexane or benzene (simple six membered ring compounds) are insoluble in water. Explain.
- Q:-
Write structures of the following compounds:
(i) 2-Chloro-3-methylpentane
(ii) 1-Chloro-4-ethylcyclohexane
(iii) 4-tert. Butyl-3-iodoheptane
(iv) 1,4-Dibromobut-2-ene
(v) 1-Bromo-4-sec. butyl-2-methylbenzene
Recently Viewed Questions of Class 12 Chemistry
- Q:-
Why is glass considered a super cooled liquid?
- Q:-
Which compound in each of the following pairs will react faster in SN2 reaction with OH-?
(i) CH3Br or CH3I
(ii) (CH3)3CCl or CH3Cl
- Q:-
At 300 K, 36 g of glucose present in a litre of its solution has an osmotic pressure of 4.98 bar. If the osmotic pressure of the solution is 1.52 bars at the same temperature, what would be its concentration?
- Q:-
What is meant by the following terms? Give an example of the reaction in each case.
(i) Cyanohydrin (ii) Acetal
(iii) Semicarbazone
(iv) Aldol
(v) Hemiacetal
(vi) Oxime
(vii) Ketal
(vii) Imine
(ix) 2,4-DNP-derivative
(x) Schiff's base
- Q:-
Write the Nernst equation and emf of the following cells at 298 K:
(i) Mg(s) | Mg2+(0.001M) || Cu2+(0.0001 M) | Cu(s)
(ii) Fe(s) | Fe2+(0.001M) || H+(1M)|H2(g)(1bar) | Pt(s)
(iii) Sn(s) | Sn2+(0.050 M) || H+(0.020 M) | H2(g) (1 bar) | Pt(s)
(iv) Pt(s) | Br2(l) | Br-(0.010 M) || H+(0.030 M) | H2(g) (1 bar) | Pt(s).
- Q:-
What type of bonding helps in stabilising the ∝-helix structure of proteins?
- Q:-
Calculate the standard cell potentials of galvanic cells in which the following reactions take place:
(i) 2Cr(s) + 3Cd2+(aq) → 2Cr3+(aq) + 3Cd
(ii) Fe2+(aq) + Ag+(aq) → Fe3+(aq) + Ag(s)
Calculate the ΔrGø¸ and equilibrium constant of the reactions.
- Q:-
Predict the products of electrolysis in each of the following:
(i) An aqueous solution of AgNO3 with silver electrodes.
(ii) An aqueous solution of AgNO3with platinum electrodes.
(iii) A dilute solution of H2SO4with platinum electrodes.
(iv) An aqueous solution of CuCl2 with platinum electrodes.
- Q:-
Distinguish between the terms homopolymer and copolymer and give an example of each.
- Q:-
Vapour pressure of pure acetone and chloroform at 328 K are 741.8 mm Hg and 632.8 mm Hg respectively. Assuming that they form ideal solution over the entire range of composition, plot ptotal' pchloroform' and pacetoneas a function of xacetone. The experimental data observed for different compositions of mixture is.
100 ×xacetone
0 11.8 23.4 36.0 50.8 58.2 64.5 72.1 pacetone /mm Hg
0 54.9 110.1 202.4 322.7 405.9 454.1 521.1 pchloroform/mm Hg
632.8 548.1 469.4 359.7 257.7 193.6 161.2 120.7
5 Comment(s) on this Question
Nice answer . To the point , not too big not too small . Keep up the good work guys
I love you webside it has each and every ans which we want i like it
Too longð¥
i like it
program is very interesting
- All Chapters Of Class 12 Chemistry
- All Subjects Of Class 12