|

Physical Chemistry

Cool goIITian

 Joined: 22 Mar 2012 Post: 35
5 Apr 2012 20:21:20 IST
0 People liked this
2
371
In a first order reaction, concentration of the reactant,decreases from 0.8M TO 0.4M in 15 min. Then
Engineering Entrance , Medical Entrance , NEET , JEE Main , AIIMS , JEE Main & Advanced , Chemistry , Physical Chemistry

In a first order reaction, concentration of the reactant,decreases from 0.8M TO 0.4M in 15 min. Then, 0.1M Becomes 0.025M in how many min?

Hot goIITian

Joined: 4 Apr 2012
Posts: 121
5 Apr 2012 21:23:09 IST
0 people liked this

30 minutes coz two half lifes are spent.................................................................0.8 to 0.4 in 15 minutes=> 0.4 to 0.2 15 min........0.2 to 0.1 in 15 min.............. 0.1 to 0.05 in 15min. , ..........0.05 to 0.025 in 15min.... so in 30 minutes..........

Forum Expert
Joined: 23 Jan 2007
Posts: 7958
5 Apr 2012 22:26:41 IST
0 people liked this

0.8M becomes 0.4M in 15 min so half life is 15 min

$C=\frac{C_{0}}{2^n}$   where n is no. of half lives

$0.025=\frac{0.1}{2^n}\; \; \Rightarrow \; \; n=2$

So required time is 2x15 = 30 min

 Some HTML allowed. Keep your comments above the belt or risk having them deleted. Signup for a avatar to have your pictures show up by your comment If Members see a thread that violates the Posting Rules, bring it to the attention of the Moderator Team

## For Quick Info

Name

Mobile

E-mail

City

Class

Vertical Limit

Top Contributors
All Time This Month Last Week
1. Bipin Dubey
 Altitude - 16545 m Post - 7958
2. Himanshu
 Altitude - 10925 m Post - 3836
3. Hari Shankar
 Altitude - 10085 m Post - 2217
4. edison
 Altitude - 10825 m Post - 7804
5. Sagar Saxena
 Altitude - 8635 m Post - 8064
 Altitude - 6330 m Post - 1958

Physics

Topics

Mathematics

Chemistry

Biology

Institutes

Parents Corner

Board

Fun Zone