A reaction is second order respect to the reactant A. If the reaction is 85% complete in 12 minutes, how long would it take for the reaction to be 15% complete?
a. 110s
b. 27s
c. 62s
d.130s
e. 22s

e. 22s

Explanation:

Initial Concentration = 100

Final concentration = 15 ( Since the reaction is 85% complete)

Time = 12 minutes = 720 seconds

The integrated rate law for second order reactions is given as;

1 / [A] = (1 / [A]o) + kt

Making k subject of interest, we have;

kt = (1 / [A] ) - (1 / [A]o )

k = (1 / [A] ) - (1 / [A]o ) / t

k = [(1/ 15) - (1 / 100) ] / 720

k = (0.0667 - 0.01 ) / 720

k = 0.0567 / 720

k = 7.875e^-5

How long would it take for the reaction to be 15% complete?

Final concentration = 85 (Since the reaction would be 15% complete)

The integrated rate law for second order reactions is given as;

1 / [A] = (1 / [A]o) + kt

Making t subject of interest, we have;

kt = (1 / [A] ) - (1 / [A]o )

t = (1 / [A] ) - (1 / [A]o ) / k

t = [(1 / 85 ) - (1 / 100) ] / 7.875e^-5

t = (0.0117 - 0.01 ) / 7.875e^-5

t = 0.001765 / 7.875e^-5

t = 22.41 seconds

Corect option = E.

number of molecules / avogadro's number * molecule molecular = mass

explanation:

we define a gram-molecular weight as the mass of one mole of any element or compound. a mole contains avogadro's number of units (molecules) –  

6.022

x

10

23

. so, dividing the number of molecules by avogadro's number gives us the number of moles. multiplying that by the molecular weight gives us the mass. from the periodic table we find the gram-molecular weight of u to be238 and of f to be19. so,  

u

f

6

will have a gram-molecular weight of 352g.