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

hydrocarbons are organic compounds that contain only hydrogens and carbons. they can be saturated (those which contain only carbon-carbon single bonds) or unsaturated (those which contain carbon-carbon double or triple bonds) in nature. hydrocarbons can undergo several reactions like substitution, elimination etc.  

on substituting one or more hydrogen atoms in hydrocarbon it results in the formation of haloalkane. as the halogen atoms are large compared to the carbon and hydrogen atoms, due to which the molecular weight increases and the bond become polar because of presence electronegative halogen atom and results in the increase in boiling point of the haloalkane.

thus, the correct option is (b) that is the boiling point of the new compound increases on substituting a hydrogen atom with a halogen in a hydrocarbon.