For a first-order reaction, after 2.00 min, 20% of the reactants remain. Calculate the rate constant for the reaction. 1. 74.6 s−1 2. 0.00582 s−1 3. 0.000808 s−1 4. 0.00186 s−1 5. 0.013412 s−1

The rate constant for the reaction is

Explanation:

Rate law expression for first order kinetics is given by the equation:

where,

k = rate constant  = ?

t = time taken for decay process = 2.00 min = 120 seconds   (Conversion factor: 1 min = 60 seconds)

= initial amount of the sample = 100 grams

[A] = amount left after decay process =  20 grams

Putting values in above equation, we get:

Hence, the rate constant for the reaction is

  the   balanced   equation   for   reaction of   ca metal   with   o2 to   produce   cao   is as below

2 ca+ o2→ 2 cao2

  explanation

the reaction is   balanced     since the   number of atoms   in reactant side is   equal to   number of atoms   in   product side.   for   example   they   are 2   atom of   ca in   reactant   side   and   2   atoms of ca   in   the product side.

  the   process   is a   meet the   requirement   of   redox   reaction because :     calcium   is   oxidized   from   oxidation state 0   to 2+   while   oxygen   is reduced from   oxidation   state   0   to 2-