Problem Solving

Please help! Thank you (From Powerprep)

The rate of a certain chemical reaction is directly proportional to the square of the concentration of chemical A present and inversely proportional to the concentration of chemical B present. If the concentration of chemical B is incresed by 100 percent, which of the following is closest to the percent change in the concentration of chemical A required to keep the reaction rate unchanged?

a) 100% decrease
b) 50% decrease
c) 40% decrease
d) 40 % increase
e) 50% increase

hnature0704 wrote:Please help! Thank you (From Powerprep)

The rate of a certain chemical reaction is directly proportional to the square of the concentration of chemical A present and inversely proportional to the concentration of chemical B present. If the concentration of chemical B is incresed by 100 percent, which of the following is closest to the percent change in the concentration of chemical A required to keep the reaction rate unchanged?

a) 100% decrease
b) 50% decrease
c) 40% decrease
d) 40 % increase
e) 50% increase

R = k (Ca)^2/(Cb)
Can-new Ca
Cb increased by 100% i.e. Cb is doubled.
New R = k (Can) ^2/2Cb = k (Ca) ^2/Cb
cancel out Cb.
Can ^2 = 2. Ca ^2
Take square root of both sides.
(New Ca)Can = (2)^(1/2) Ca
(2)^1/2 is = 1.41
Therefore % increase in Concentration of chemical A = 40%