Consider the reaction alatex: \longrightarrow ⟶ products. the rate law for this reaction is rate = k[a]2 where k=2.90 latex: \times × 10-2 m-1s-1 at a particular temperature. if the initial [a] = 0.0500 m, what is the value of the half-life?
478 s
34.5 s
690. s
23.9 s

690 s

Explanation: Rate law says that rate of a reaction is directly proportional to the concentration of the reactants each raised to a stoichiometric coefficient determined experimentally called as order.

For a reaction:

k= rate constant=

x = 2= order with respect to A

For a second order reaction,

= half life = time taken for a reaction to complete to half.  

=initial concentration= 0.0500 M

Thus

since the atomic number is the number of protons in the nucleus, as we move to the left on the periodic table, the electrostatic pull between the nucleus and the valence electron shell decreases. as we move down a group (vertical column), the valence shell energy level gets further and further from the nucleus.