Question

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 increased 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?

Answer 1

Answer:

40% increase

Explanation:

The rate of the chemical, R ∝ $A^2 / B$

The rate of the chemical,  R= $k * A^2 / B$ where k is a constant

Hence $R*B/A^2 = constant$

Hence $R1*B1/A1^2 = R2*B2/A2^2$

Concentration of B is increased by 100% i.e concentration is doubled

Hence B2=2*B1

R is constant i.e R1=R2

$R1*B1/A1^2 = R1*2B1/A2^2$

Solving, we have that

$A2^2= 2*A1^2$

Hence $A2=\sqrt{2} * A1$

A2= 1.41*A1

This represents approximately a 40% increase in the value of A1