January 29, 2023, 02:30:24 PM
Forum Rules: Read This Before Posting


Topic: A better way?  (Read 2664 times)

0 Members and 1 Guest are viewing this topic.

Offline student8607

  • Full Member
  • ****
  • Posts: 227
  • Mole Snacks: +2/-3
A better way?
« on: January 31, 2009, 06:20:44 PM »
first order reaction
rate constant at 427k: 5.11x10-5
initial concentration is 0.0340M


I know half life: 0.693/5.11x10-5 = 1,3561sec --> 3.7hour
Is there a method for solving these above questions or is it just about estimation of what you know?


question 1: what is the molarity after 2.00hour?
I got about 0.0183 molar

question 2: how many minutes does it take for concentration to drop to 0.0300M?
I got about 1 minute

question 3: how many minutes does it take for 20% to react?
I got about 90.4 minutes

Offline TheJoker

  • Regular Member
  • ***
  • Posts: 10
  • Mole Snacks: +1/-0
Re: A better way?
« Reply #1 on: January 31, 2009, 06:47:16 PM »
you probably used this but just in case ,   for 1st order reactions:

ln([A]at time t / [A]initial ) = -kt

Offline student8607

  • Full Member
  • ****
  • Posts: 227
  • Mole Snacks: +2/-3
Re: A better way?
« Reply #2 on: January 31, 2009, 09:03:51 PM »
Ahhhh. I knew there was an equation for that.

Thanks!

Sponsored Links