Aug 7, 2011
21
0
Status
Pre-Medical
Why is the half life of a first order reaction constant? Doesn't the reaction rate decrease over time in first order reaction?
 

salim271

Patience is tough. :/
May 21, 2011
546
2
30
Michigan
Status
Pre-Medical
Why is the half life of a first order reaction constant? Doesn't the reaction rate decrease over time in first order reaction?
The half life of a 1st order reaction is constantly decreasing because the rate of the reaction only depends on one of the reaction components. When that component is half gone, the reaction rate is halved by the same amount.
 

indianjatt

10+ Year Member
Sep 23, 2009
685
27
California
Status
Pre-Medical
The half life is always constant for a first order reaction. For a first ordered reaction the half life time is .6930/rate constant and the rate constant doesn't change... it's a constant. Yes, you're right the reaction rate goes down, but that's because the concentration of [A] is decreasing with time. It doesn't affect the half life. This ones more of looking at the equation.
 
About the Ads