The reaction CH3NC? CH3CN is called an isomerization reaction andinvolves the breaking of a C-N bond and subsequent formation of a C-C bond-the reactant andproduct have the same molecular formulas and so are isomers. This reaction has a rate constant of0.46 s-1 at a specific temperature. What is the concentration of CH3NC after 0.20 min if its initialconcentration is 0.10 M? A. 4.0 * 10-4 M B. 7.6 * 10-6 M C. 8.5 * 10-2 MD. 9.1 * 10-2 M E. 2.5 * 10-2 M

Answer

A

Explanation:

CH3NC - -> CH3CN

k = 0.46 s-1

In first order reactions, the reaction rate is directly proportional to the reactant concentration and the units of first order rate constants are 1/sec.

So the reaction is a first order reaction.

t = 0.20 min = 12 s (Converting to seconds multiply the time value by 60)

initial concentration [A]o = 0.10 M

Final Concentration [A] = ?

Formular relating these parameters is given as;

Making [A] subject of interest, we have';

ln[A] = ln[A]o - kt

In[A] = In (0.10) - (0.46*12)

In[A] = - 7.8226

[A] = e^ (-7.8226)

[A] = 0.000401

[A] = 4 * 10^-4M