Troubles here:
The rate of a chemical reaction is directly proportional to the square of the concentration of chemical A, and inversely proportional to the concentration of chemical B present.
If conentration of B is increased by 100%, which of the following is closest to percentage change in concentration of chemical A required to keep the rate unchanged.
Ans = +40%
Any help is qreatly appreciated...
GmatPrep Question...
This topic has expert replies
The rate of a chemical reaction is directly proportional to the square of the concentration of chemical A, and inversely proportional to the concentration of chemical B present.
This means that the rate couldbe written as R =K * CA^2/CB
Where K is a constant
CA is the concentration ofchemical A
CB is the concentration ofchemical B
* If conentration of B is increased by 100%, it means that the
Let R1 = CA1^2/ CB1, be the rate befre CB changed
and R2 = CA2^2/ CB2, the rate after CB doubled ( increased by 100%)
To keep the rate unchanged, we would have to fit the following equation :
R1=R2, this means that CA2 ^2/CB2 = CA1^2/CB1
AS CB2 = 2 CB1
THEN, CA2^2 = 2 * CA1^2
CA2 = SQUARE Root of 2* CA1 = 1,4 CA1
tHIS MEANS THAT Ans = +40%
GOOD LUCK
This means that the rate couldbe written as R =K * CA^2/CB
Where K is a constant
CA is the concentration ofchemical A
CB is the concentration ofchemical B
* If conentration of B is increased by 100%, it means that the
Let R1 = CA1^2/ CB1, be the rate befre CB changed
and R2 = CA2^2/ CB2, the rate after CB doubled ( increased by 100%)
To keep the rate unchanged, we would have to fit the following equation :
R1=R2, this means that CA2 ^2/CB2 = CA1^2/CB1
AS CB2 = 2 CB1
THEN, CA2^2 = 2 * CA1^2
CA2 = SQUARE Root of 2* CA1 = 1,4 CA1
tHIS MEANS THAT Ans = +40%
GOOD LUCK
I appologize for my Frenchy-English.
I am working on it.
I am working on it.
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hey
Fei,
How have you been?
Why do you still want to solve GMAT Math problems? you are already done with it
Are you thinking of retaking it ?
As Stacey says we should provide the complete problem alongwith source of it. It's for good. 8)
Anyway it seems that bonana has already replied to you.
Fei,
How have you been?
Why do you still want to solve GMAT Math problems? you are already done with it
Are you thinking of retaking it ?
As Stacey says we should provide the complete problem alongwith source of it. It's for good. 8)
Anyway it seems that bonana has already replied to you.
Getting started @BTG?
Beginner's Guide to GMAT | Beating GMAT & beyond
Please do not PM me, (not active anymore) contact Eric.
Beginner's Guide to GMAT | Beating GMAT & beyond
Please do not PM me, (not active anymore) contact Eric.
I got the same question in my prep test.
R= [K(A^2)]/; where K is a constant.
In this question 3 answer choices can be eliminated without solving:
To keep the fraction constant, if the denominator is increased the numerator has to increase.
3 answer choices mentioned a decrease and hence can be eliminated
To calculate the percentage increase of A
B-->2B i.e. B changes from B to 2B
A^2--> 2.A^2 i.e. A^2 has to change from A^2 to 2.A^2
A^2 = 2. A^2
A = sqrt2. A
Thus, A has to increase to sqrt2.A
Percent increase from A to sqrt2.A is approx 40%
R= [K(A^2)]/; where K is a constant.
In this question 3 answer choices can be eliminated without solving:
To keep the fraction constant, if the denominator is increased the numerator has to increase.
3 answer choices mentioned a decrease and hence can be eliminated
To calculate the percentage increase of A
B-->2B i.e. B changes from B to 2B
A^2--> 2.A^2 i.e. A^2 has to change from A^2 to 2.A^2
A^2 = 2. A^2
A = sqrt2. A
Thus, A has to increase to sqrt2.A
Percent increase from A to sqrt2.A is approx 40%