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प्रश्न
How does calcination differ from roasting?
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उत्तर
| Roasting | Calcination |
| Ore is heated in excess of air. | Ore is heated in the absence or limited supply of air. |
| This is used for sulphide ores. | This is used for carbonate ores. |
| SO2 is produced along with metal oxide. | CO2 is produced along with metal oxide. |
| e.g. \[\ce{ 2ZnS + 3O2 ->[\Delta] 2ZnO + 2SO2}\] | e.g. \[\ce{ZnCO3 ->[\Delta] ZnO + CO2}\] |
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संबंधित प्रश्न
Define “zero order reaction”.
A reaction is second order in A and first order in B.
(i) Write the differential rate equation.
(ii) How is the rate affected on increasing the concentration of A three times?
(iii) How is the rate affected when the concentrations of both A and B are doubled?
What is pseudo first order reaction? Give one· example of it.
Write molecularity of the following reaction:
2NO(g)+O2(g)→2NO2(g)
For a reaction: 
Rate = k
(i) Write the order and molecularity of this reaction.
(ii) Write the unit of k.
For the first order thermal decomposition reaction, the following data were obtained:
Time / sec Totalpressure / atm
0 0.30
300 0.50
Calculate the rate constant
(Given: log 2 = 0.301, log3 = 0.4771, log 4 = 0.6021)
A reaction is first order in A and second order in B. How is the rate affected when the concentrations of both A and B are doubled?
The decomposition of N2O5(g) at 320K according to the following equation follows first order reaction:
`N_2O_(5(g))->2NO_(2(g))+1/2O_(2(g))`
The initial concentration of N2O5(g) is 1.24 x 10-2 mol. L-1 and after 60 minutes 0.20x10-2 molL-1. Calculate the rate constant of the reaction at 320K.
Write the principle behind the following methods of refining:
Hydraulic washing
What is the order of a reaction which has a rate expression; Rate = `"k"["A"]^(3/2)["B"]^1`?
Compounds ‘A’ and ‘B’ react according to the following chemical equation.
\[\ce{A(g) + 2B(g) -> 2C(g)}\]
Concentration of either ‘A’ or ‘B’ were changed keeping the concentrations of one of the reactants constant and rates were measured as a function of initial concentration. Following results were obtained. Choose the correct option for the rate equations for this reaction.
| Experiment | Initial concentration of [A]/mol L–¹ |
Initial concentration of [B]/mol L–¹ |
Initial rate of formation of [C]/mol L–¹ s–¹ |
| 1. | 0.30 | 0.30 | 0.10 |
| 2. | 0.30 | 0.60 | 0.40 |
| 3. | 0.60 | 0.30 | 0.20 |
The value of rate constant of a pseudo first order reaction ______.
Consider the reaction A ⇌ B. The concentration of both the reactants and the products varies exponentially with time. Which of the following figures correctly describes the change in concentration of reactants and products with time?
Why molecularity is applicable only for elementary reactions and order is applicable for elementary as well as complex reactions?
Why can we not determine the order of a reaction by taking into consideration the balanced chemical equation?
The role of a catalyst is to change
For a first order A → B, the reaction rate at reactant concentration of 0.01 m is found to be 2.0 × 10–5. The half-life period of reaction.
At concentration of 0.1 and 0.2 mol L–1 the rates of deem position of a compound were found to be 0.18 and 0.72 mol L–1 m–1. What is the order of the reaction?
The number of molecules of the reactants taking part in a single step of the reaction is indicative of ______.
Identify the order of reaction from the following unit for its rate constant:
L mol–1 s–1
On heating compound (A) gives a gas (B) which is constituent of air. The gas when treated with H2 in the presence of catalyst gives another gas (C) which is basic in nature, (A) should not be ______.
The following data was obtained for chemical reaction given below at 975 K.
\[\ce{2NO(g) + 2H2(g) -> N2(g) + 2H2O(g)}\]
| [NO] | [H2] | Rate | |
| Mol L-1 | Mol L-1 | Mol L-1 s-1 | |
| (1) | 8 × 10-5 | 8 × 10-5 | 7 × 10-9 |
| (2) | 24 × 10-5 | 8 × 10-5 | 2.1 × 10-8 |
| (3) | 24 × 10-5 | 32 × 10-5 | 8.4 × 10-8 |
The order of the reaction with respect to NO is ______. (Integer answer)
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 flask contains a mixture of compounds A and B. Both compounds decompose by first-order kinetics. The half-lives for A and B are 300 s and 180 s, respectively. If the concentrations of A and B are equal initially, the time required for the concentration of A to be four times that of B (in s) is ______. (Use ln 2 = 0.693)
Assertion (A): Order of reaction is applicable to elementary as well as complex reactions.
Reason (R): For a complex reaction, molecularity has no meaning.
Which of the following statement is true?
