A small amount of reactant \"X\" is added to water containing cyclochemical at a
ID: 524100 • Letter: A
Question
A small amount of reactant "X" is added to water containing cyclochemical at a concentration of 1E-4 mole/L that undergoes a first-order reaction with cyclochemical with a reaction rate constant of k = 0.2 s^-1 (Assume the volume of water is constant.) The reaction proceeds very quickly relative to mass transfer (i.e. assume during the reaction there is a negligible amount of chemical diffusion from the headspace into the liquid) and the chemical reactant "X" is completely used up after only 5 seconds. What is the concentration (mol/L) of cyclochemical in the water right after this reaction step?Explanation / Answer
Given
Co = 1 * 10-4 mol/L
k = 0.2 s-1
t = 6 s
first order rate law
-dC/dt = kC
-dC / C = k dt
integrating and applying limits
- ln (C/Co) = kt
sub given values
- ln ( C / 1 * 10-4 mol/L ) = 0.2 s-1 * 6 s
- ln ( C / 1 * 10-4 mol/L ) = 1.2
(C / 1 * 10-4 mol/L ) = exp(-1.2)
C = 0.3012 * 1 * 10-4 mol/L = 0.3 * 10-4 mol/L
so this is concentration of cyclochemical in water right after reaction