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Read the passage given below and answer the questions that follow : The rate law for a chemical reaction relates the reaction rate with the concentrations or partial pressures of the reactants. For a general reaction aA + bB → C with no intermediate steps in its reaction mechanism, meaning that it is an elementary reaction, the rate law is given by r = k[A]x[B]y, where [A] and [B] express the concentrations of A and B in moles per litre. Exponents x and y vary for each reaction and are determined experimentally. The value of k varies with conditions that affect reaction rate, such as temperature, pressure, surface area, etc. The sum of these exponents is known as overall reaction order. A zero order reaction has a constant rate that is independent of the concentration of the reactants. A first order reaction depends on the concentration of only one reactant. A reaction is said to be second order when the overall order is two. Once we have determined the order of the reaction, we can go back and plug in one set of our initial values and solve for k.
Observe the graph shown in figure and answer the following questions :
The variation in the concentration (R) vs. time (t) plot is given below. Answer the following questions on the basis of the given figure :
A first order reaction takes 24 minutes for 50% decomposition. Calculate the time required for 25% decomposition. (Given : log 4 = 0·6021, log 3 = 0·4771)
A first order reduction takes 30 minutes for 75% decomposition. Calculate t₁/₂. Given : [log 2 = 0·3, log 3 = 0·48, log 4 = 0·6, log 5 = 0·7]
Read the following passage and answer the questions that follow : The rate of reaction is concerned with decrease in concentration of reactants or increase in the concentration of products per unit time. It can be expressed as instantaneous rate at a particular instant of time and average rate over a large interval of time. A number of factors such as temperature, concentration of reactants, catalyst affect the rate of reaction. Mathematical representation of rate of a reaction is given by rate law : Rate = k[A]^x [B]^y x and y indicate how sensitive the rate is to the change in concentration of A and B. Sum of x + y gives the overall order of a reaction. When a sequence of elementary reactions gives us the products, the reactions are called complex reactions. Molecularity and order of an elementary reaction are same. Zero order reactions are relatively uncommon but they occur under special conditions. All natural and artificial radioactive decay of unstable nuclei take place by first order kinetics.
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