This set of Solid State Chemistry Multiple Choice Questions & Answers (MCQs) focuses on “Solid State Reaction”.
1. For the preparation of polycrystalline solids (i.e. powder), a mixture of solid starting materials directly react with each other in the solid state. What is the range of the temperature usually required for the solids to react together in Celsius?
a) 25 to 37
b) 1000 to 1500
c) -25 to 0
d) 2000 to 3000
Explanation: Solids don’t react usually at room temperature over normal scale timescale, It is required to heat them at much higher temperature often 1000◦C to 1500◦C, in order for a reaction to occur at an appreciable rate.
2. What are the major important factors for the solid state reactions?
a) Size of the particles
b) Mechanical properties of solids
c) Thermodynamic and kinetic factors
d) Environmental factors
Explanation: In Solid state reactions thermodynamic factors show whether or not a particular reaction should occur by considering the change in free energy that are involved and kinetic factors determine the rate at which the reaction occurs.
3. In the solid state reaction, which mechanism describes the reaction between MgO and Al2O3 for the formation of MgAl2O4?
a) Mannich reaction
b) Aromic ion mechanism
c) Wagner mechanism
d) Witting reaction
Explanation: The mechanism of reaction between MgO and Al2O3 involves the counter diffusion of Mg2++ and Al3++ through the product layer followed by further reaction at two reactant-product interfaces, and this is known as Wagner reaction.
4. In the solid state reaction when MgO and F2O3 reacts to form MgFe2O4,it is clear found that the interfaces moved in the ratio of 1:2.7,close to the ideal value 1:3.This is can be described by which of the following mechanism in which the movement of the interfaces is used as a marker?
a) Kirkedall Effect
b) Grignard Reaction
c) Michael Reaction
d) Aldol Reaction
Explanation: In the reaction such as the formation of the MgFe2O4, in which the interfaces between the reaction and the product can be clearly seen, perhaps due to a difference in color, the movement of the interfaces can be used as a marker to monitor the progress of the reaction. This effect of using a marker is known as the Kirkendall effect.
5. For the formation of ZnFe2O4 spinel which method can be used in order to achieve high degree of homogenization?
a) Distillation method
b) Vaporization method
c) Coprecipitation method
d) Crystallization method
Explanation: In normal solid state reaction, the reactants are mixed together manually or mechanically and the subsequent reaction rate depends largely on the degree of homogenization achieved on mixing and the intimacy of contact between the grains. With the Coprecipitation method it is possible a high degree of homogenization together with small particle size and thereby speed up the reaction rate.
6. For the solid state syntheses of ferrite spinels, it is ______________ for the precursor methods to yield phases of accurate stoichiometry
b) Not necessary
Explanation: It is important for the precursor methods to yield the phases of accurate stoichiometry by careful control of the experimental conditions since several chromites and ferrites are valuable magnetic materials whose properties may be sensitive to purity and stoichiometry.
7. What is the ignition temperature required for the synthesis of Manganese Chromite MnCr2O4, a chromite spinel during the precursor method in degree Celsius?
Explanation: During the synthesis of manganese chromite using precursor method the ignition temperature required is 1100 degree Celsius to ensure that all the manganese are present in the divalent state.
8. The appropriate relation between the surface area of any solid with that of the particle size can be stated as
a) Surface area of any solid increases with increase in particle size
b) Surface area of any solid is always equal to the particle size
c) Surface area of any solid increases with decrease in particle size
d) Surface area of any solid doesn’t depend at all on the particle size
Explanation: Surface area is always inversely related with the particle size. In the form of a single crystal, a few grams of solid has a surface area about to equal to the area of a large postage stamp. In the form of a finely divided powder, its surface area is about equal to the area of a hundred meter running track. Hence surface area increases with decrease in particle size.
9. During the reactivity of solids, two stages that may usually be identified are Nucleation of the product and its subsequent growth. When is nucleation facilitated?
a) When there is a structural similarity between the products
b) When there is structural similarity between the reactants
c) When there is structural dissimilarity between the product and the reactant
d) When there is structural similarity between the product and the reactant
Explanation: Nucleation is facilitated if there is structural similarity between the product and one or both of the reactants because this reduces the amount of structural reorganization that is necessary for nucleation to occur.
10. What is the relation between Topotactic reaction and epitactic reactions?
a) Topotactic reactions are less specific than epitactic reactions
b) Topotactic reactions are equally specific than epitactic reactions
c) Topotactic reactions are more specific than epitactic reactions
d) Topotactic reactions can’t be related to epitactic reactions
Explanation: Topotactic and epitactic reactions are the orientated reactions or transformation when nucleation makes use of structural similarity. Topotactic reactions are more specific than epitactic reaction because they require not only the structural similarity at the interface but also that this similarity should continue into the bulk of both crystalline phases.
Sanfoundry Global Education & Learning Series – Solid State Chemistry.
To practice all areas of Solid State Chemistry, here is complete set of 1000+ Multiple Choice Questions and Answers.