Explore topic-wise InterviewSolutions in .

(b) common salt solution

(a) chromium salt

(iii), (iv)

(iii) Reversible colloids.

(iv) Lyophilic colloids.

(i), (iii)

(i) Lyophobic sol is protected.

(iii) Film of lyophilic sol is formed over lyophobic sol.

(ii), (iii)

(ii) Electroosmosis takes place.

(iii) Dispersion medium begins to move.

(d) All the above

(d) Hydrolysis of cane sugar with mineral acid

(b) Decomposition of H₂O₂ in the presence of Pt catalyst

(c) Acid hydrolysis of ester

(d) (ii) only

Both are colloidal solutions. Sol has solid as ‘dispersed phase & liquid as dispersion medium’. While ‘Gel’ has liquid as dispersed phase and solid as dispersion medium.

Sol

1. The liquid state of a colloidal solution is called sol. 

2. The sol does not have a definite structure. 

3. The dispersion medium of the sol may be water. 

4. The sol can be converted to gel by cooling The sol can be easily dehydrated.

5. The viscosity of the sol is very low. 

6. Sol is categorized into lyophobic and lyophilic sols. 

7. Example: Blood

Gel 

1. The solid or semi solid state of a colloidal solution is called gel. 

2. The gel possesses honey comb like structure. 

3. The dispersion medium of gel will be hydrated colloid particles. 

4. The gel can be converted sol by heating. 

5. The gel cannot be dehydrated. 

6. The viscosity of the gel is very high. 

7. There is no such classification of gel. 

8. Example: Fruit jelly, cooked gelatin jelly.

The coarse suspension of the substance is introduced in the colloid mill that consists of two metal discs close together rotating at a high speed in the opposite directions. Here the suspension particles are broken to the colloidal size.

 Arsenic sulphide. 

Ferric hydro-oxide sol.

Micelles are associated colloids which behave as normal strong electrolytes at low concentration but behave as colloidal particles at higher concentrations. 

For example:- soap molecules when dissolved in water gives sodium and stearate ions. The stearate ions associate to form ionic micelles of colloidal size. 

C₁₇H₃₅COONa ↔ C₁₇H₃₅COO^- + Na⁺

Soap is sodium salt of fatty acids (RCOONa) which when dissolved in water dissociates to give RCOO^- and Na⁺. The RCOO consists of polar group COO which is hydrophilic and stays at the surface and the non polar group R which being hydrophobic stays away from the surface. At high concentrations RCOO ions are pulled into the solution to form spherical aggregates with R pointing to the centre COO^- part remaining outward. This aggregate is known as ionic micelle.

Sodium stearate (C₁₇ H₃₅ COO^- Na⁺) 

In heterogeneous catalysis the reaction always starts at the surface of the catalyst. So, it is also known as surface catalysis. 

(i), (iii)

(i) When 1/n = 0, the adsorption is independent of pressure. 

(iii) When n = 0, x/m vs p graph is a line parallel to x-axis.

Milk belong to oil in water type emulsion, where dispersed phase is oil and dispersion medium is water.

(i) Rough surface of a catalyst provides more surface area for adsorption. 

(ii) So that unburnt charged carbon particles get settled between the charged plate leaving behind air free from pollutants.

(iii) Ne has higher critical temperature i.e., stronger van der Waals forces therefore gets easily adsorbed.

Application of adsorption:- 

(a) Removal of colouring matter from solution using animal charcoal. 

(b) Chromatographic analysis is based on adsorption. 

a) Physical adsorption or physisorption and chemical adsorption or chemisorption,

b)

On the basis of interaction between adsorption and absorption, adsorbate are of two types: 

(i) Physical adsorption/physisorption: When weak vander waal interaction involve between adsorbate and adsorbent. 

(ii) Chemical adsorption/chemisorption: When chemical bonds form between adsorbate and adsorbent. 

The variation in the amount of gas adsorbed by the adsorbent with pressure at constant temperature can be expressed by means of a curve termed as adsorption isotherm. 

Cheese is a gel in which dispersed phase is liquid and dispersion medium is solid.

2Na₂SO₃ + O₂ \(\overset{fast}{\rightarrow}\) Na₂SO₄
Na₃AsO₃ + O₂ → No reaction
Na₂SO₃ + Na₃AsO₃ +O2 → Na₂SO₄ + Na₃AsO₄

Example of homogeneous catalysis:
2SO_2(g) + O_2(g) \(\overset { NO_{ (g) } } {\longrightarrow}\) 2SO_3(g)
Example of heterogeneous catalysis:
N_2(g) + 3H_(g) \(\overset{ Fe_{ (s) } } {\longrightarrow}\) 2NH_3(g)

Highly reactive metal or highly electropositive. e.g. Na₂O.

To reduce the melting point of alumina and make it more conductive.

1 Kg  graphite is consumed to get 2 Kg Aluminium.

Duralumin is used in making aero plane.

Because oxygen liberates at anode and in presence of oxygen , graphite rod get consume to produce CO₂.

1. AlCl₃

2. NaCl < BaCl₂ < AlCl₃

3. Hardy – Schulze rule. It states that greater the valence of the flocculating ion greater is its power to cause precipitation.

(i) x/m = kC^1/1n

(ii) The charge on the sol particles is due to 

(a) Electron capture by sol particles during electrodispersion. 

(b) Preferential adsorption of ions from solution. 

(c) Formulation of electrical double layer.

(iii) Molybdenum acts as a promoter for iron.

Molten NaCl is preferred because Molten NaCl on electrolysis gives sodium but aqueous NaCl produces NaOH instead of Sodium.

Zinc is used in galvanization of iron.

German silver is an alloy of Cu. Its composition is Cu = 25-30%, Zn = 25-30%, Ni = 40-50%.

It is used for making artificial jewelry.

The process of setting of colloidal particles is called coagulation of the sol. 

(d) Electrolytic process.

The answer is (d) AlCl₃

(c) milk of magnesia

Movement of Colloidal particles towards opposite electrode in presence of external electric field is called electrophoresis.

(c) colloidal Au & colloidal Ca

Properties of colloidal solution:

(1) They show colligative properties 

(2) Brownian movement - zig-zag motion of colloidal particles 

(3) Tyndall effect- scattering of light by colloidal particles by which path of beam becomes clearly visible. This effect is known as tyndall effect.

(c) Dialysis

(c) Alum containing Al³⁺