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प्रश्न
Write the principle behind the following methods of refining:
Hydraulic washing
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उत्तर
The principle behind the given methods of refining are:
i) Hydraulic Washing:
This method is based on difference of gravity between ores and gangue. An upward stream of water is used to wash the powdered ore. The lighter gangue particles are washed away, leaving behind the heavier ones.
ii) Vapour-phase refining:
Vapour-phase refining is the process of refining metal by converting it into its volatile compound and then, decomposing it to obtain a pure metal. To carry out this process,
(i) the metal should form a volatile compound with an available reagent.
(ii) the volatile compound should be easily decomposable, so that the metal can be easily recovered. This method is used for refining nickel, zirconium and titanium.
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संबंधित प्रश्न
Define “zero order reaction”.
For a chemical reaction R → P, the variation in the concentration (R) vs. time (t) plot is given as:
(i) Predict the order of the reaction.
(ii) What is the slope of the curve?
(iii) Write the unit of rate constant for this reaction.
Mention the factors that affect the rate of a chemical reaction.
A reaction is second order with respect to a reactant. How is the rate of reaction affected if the concentration of the reactant is doubled?
For a general reaction A → B, plot of concentration of A vs time is given in figure. Answer the following question on the basis of this graph.
(i) What is the order of the reaction?
(ii) What is the slope of the curve?
(iii) What are the units of rate constant?
Why molecularity is applicable only for elementary reactions and order is applicable for elementary as well as complex reactions?
Assertion: Rate constants determined from Arrhenius equation are fairly accurate for simple as well as complex molecules.
Reason: Reactant molecules undergo chemical change irrespective of their orientation during collision.
For a reaction 1/2 A ⇒ 2B, rate of disappearance of A is related 't o the appearance of B by the expression:
For a chemical reaction starting with some initial concentration of reactant At as a function of time (t) is given by the equation,
`1/("A"_"t"^4) = 2 + 1.5 xx 10^-3` t
The rate of disappearance of [A] is ____ × 10-2 M/sec when [A] = 2 M.
[Given: [At] in M and t in sec.]
[Express your answer in terms of 10-2 M /s]
[Round off your answer if required]
A reaction is second order with respect to a reactant. How is the rate of reaction affected if the concentration of the reactant is reduced to half?
