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In the first order reaction the concentration of the reactants is reduced to 25% in one hour. The half life period of the reaction is …
$ 30 min 100 \% \rightarrow 50 \rightarrow 25 \% $ $ \therefore T = 2 \times t {1/2} \therefore t{1/2} = { T \over 2 } $
For the First order reaction with half life is 150 seconds, the time taken for the concentration of the reactant to fall from m/10 to m/100 will be approximately
$ 500S \rightarrow { M \over 10 } \rightarrow { M \over 20 } \rightarrow {M \over 40 } \rightarrow { M \over 80} \rightarrow { M \over 180 } $ $ \therefore T \cong 3 \times t {1/2} to 4 \times t {1/2} \cong 450 to 600 S $
For the reaction $N_2O_5 --> 2NO_2 + ½O_2 t_{½ }= 24 hrs $ . starting with 10 g of $N_2O_5$ how many grams of $N_2O_5$ will remain after a period of 96 hours ?
$ 0.63 g T = n \times {1/2} n = { 96 \over 24 } = 4 $ $ \therefore Amount left = {a \over 2 ^ n } = { 10 \over 2^ 4 } = { 10 \over 16 } = 0.63 $
In the first order reaction 75% of reactant disappeared in 1.386 h. Calculate the rate constant of reaction.
$ 2.8 \times 10 ^ {-4} S^ {-1} K = { 2.303 \over 1.386 \times 60 \times 60 } log { a \over a -0.75 a } = 2.8 \times 10^ {-4} S^{-1} $
The minimum amount of energy required for the reacting molecules to undergo reaction is called :
threshold energy.
Increase in the concentration of the reactants leads to the change in
Collision frequency
Energy of activation of an exothermic reaction is
Positive Activation energy is always Positive
The chemical reactions in which reactants require high amount of activation energy are generally ................
Slow
The rate of reaction increases with increase of temperature because ...
an increase in the number of activated molecules.
The activation energy of reaction is equal to
Threshold Energy – Energy of the reactants
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