Question

If the tropospheric concentrations of OH and CF3CH2F are 8.1×105 and 6.3×108 molecules/cm3, respectively, what is the rate of reaction at this temperature in M/s?Express the rate in molarity per second to two significant figures.

Answer 1

Answer:

2.3*10^-19 M/s

Explanation:

Generally, reaction rate is the product of the rate constant, and the concentrations of the reactants in the system. Therefore, the rate of the reaction can be expressed as:

rate = k*$[CF_{3}CH_{2}F][OH]$

The value of the rate constant k is 1.6*10^8 [1/(M*s)] at the given temperature.

$[CF_{3}CH_{2}F]$ = 6.3*10^8 molecules/cm^3

$[OH]$ = 8.1*10^5 molecules/cm^3.

However, we need to convert to mol/(L(M). Therefore:

6.3*10^8 *(1000/6.023*10^23) = 1.05*10^-12

8.1*10^5 molecules/cm^3 *(1000/6.023*10^23) = 1.3*10^-15

Thus:

rate =k*$[CF_{3}CH_{2}F][OH]$ = 1.6*10^8* 1.05*10^-12* 1.3*10^-15 =2.3*10^-19 M/s