Find all School-related info fast with the new School-Specific MBA Forum

It is currently 24 Oct 2014, 15:57

Close

GMAT Club Daily Prep

Thank you for using the timer - this advanced tool can estimate your performance and suggest more practice questions. We have subscribed you to Daily Prep Questions via email.

Customized
for You

we will pick new questions that match your level based on your Timer History

Track
Your Progress

every week, we’ll send you an estimated GMAT score based on your performance

Practice
Pays

we will pick new questions that match your level based on your Timer History

Not interested in getting valuable practice questions and articles delivered to your email? No problem, unsubscribe here.

Events & Promotions

Events & Promotions in June
Open Detailed Calendar

The rate of a certain chemical reaction is directly

  Question banks Downloads My Bookmarks Reviews Important topics  
Author Message
TAGS:
Manager
Manager
avatar
Joined: 21 Dec 2005
Posts: 105
Followers: 1

Kudos [?]: 1 [0], given: 0

The rate of a certain chemical reaction is directly [#permalink] New post 04 Apr 2006, 01:38
The rate of a certain chemical reaction is directly proportional to the square of the concetration of chemical A present and inversely proportional to the concetration of chemical B present. If the concetration of chemical B is increased by 100 percent, what is percent change in the concentration of chemical A required to keep the reaction rate unchanged?


Thanks
Senior Manager
Senior Manager
avatar
Joined: 22 Jun 2005
Posts: 364
Location: London
Followers: 1

Kudos [?]: 4 [0], given: 0

 [#permalink] New post 04 Apr 2006, 02:00
rate=A^2/B

B increases by 100

rate=A^2/2B, this means that A have to be increased by sqr(2)

rate = (sqr(2)A)^2/2B=A^2/2B

sqr(2)A/A=sqr(2)

(1-sqr(2))*100 = 41percent
Manager
Manager
avatar
Joined: 21 Dec 2005
Posts: 105
Followers: 1

Kudos [?]: 1 [0], given: 0

 [#permalink] New post 04 Apr 2006, 02:35
Thanks

What is the logic behind this

rate=A^2/2B, this means that A have to be increased by sqr(2)
Senior Manager
Senior Manager
avatar
Joined: 22 Jun 2005
Posts: 364
Location: London
Followers: 1

Kudos [?]: 4 [0], given: 0

 [#permalink] New post 04 Apr 2006, 02:51
jodeci wrote:
Thanks

What is the logic behind this

rate=A^2/2B, this means that A have to be increased by sqr(2)


I meant multiplied by sqrt(2) :)

Well, the question states:...what is percent change in the concentration of chemical A required to keep the reaction rate unchanged

so the formula according to the stem is:
rate=A^2/B

if the rate is to be the same as before, the new value for A has to be sqrt(2)*A.

(A will now be sqrt(2)*A).

So,
rate = (sqrt(2)*A)^2/2B = 2A^2/2B = A^2/B

Hope this helps!
GMAT Club Legend
GMAT Club Legend
User avatar
Joined: 07 Jul 2004
Posts: 5095
Location: Singapore
Followers: 19

Kudos [?]: 155 [0], given: 0

 [#permalink] New post 04 Apr 2006, 05:16
Rate = k(CA)^2/CB

k = constant

If CB increases by 100%, we have Rate = k (CA)^2/2CB. So we need To multiply by 2 to keep the rate constant. Thus CA needs to increase by sqrt(2) and that's about 1.4. Thus have to increase by about 40%
  [#permalink] 04 Apr 2006, 05:16
    Similar topics Author Replies Last post
Similar
Topics:
The rate of a certain chemical reaction is directly misterJJ2u 4 20 Jan 2007, 23:10
The rate of a certain chemical reaction is directly Sumithra 3 16 Dec 2006, 23:02
The rate of a certain chemical reaction is directly Dilshod 1 07 May 2006, 09:18
The rate of a certain chemical reaction is directly yaron 3 27 Aug 2005, 10:04
5 Experts publish their posts in the topic The rate of a certain chemical reaction is directly okdongdong 8 07 Aug 2005, 20:00
Display posts from previous: Sort by

The rate of a certain chemical reaction is directly

  Question banks Downloads My Bookmarks Reviews Important topics  


GMAT Club MBA Forum Home| About| Privacy Policy| Terms and Conditions| GMAT Club Rules| Contact| Sitemap

Powered by phpBB © phpBB Group and phpBB SEO

Kindly note that the GMAT® test is a registered trademark of the Graduate Management Admission Council®, and this site has neither been reviewed nor endorsed by GMAC®.