Half Life

[Lusin_Yengibaryan_3B]

How do we calculate half life for a first-order reaction? For a second order-reaction? for a zero-order reaction?

[Aaron Akhavan-Dis1B]

1st order reaction half life: t1/2 = 0.693/k. 2nd Order is: t1/2 = 1/(k[A]o). Zero order: t1/2 = ([A]o)/(2k). The little o's mean "naught."

[Armen_Isayan_2L]

Hello! In order to calculate the half-life of a first-order reaction the equation is: t½ = 0.693/k
To calculate the half-life of a second-order reaction the equation is: t½ = 1/k[Ao]
To calculate the half-life of a zero-order reaction the equation is: t½ = [Ao]/2k

[rhettfarmer-3H]

the half life is given on the outline which is pretty easy to remember.

First order is
t=.693/k

2nd is

t=1/kA intial

Zero is
t=Aintial/2k

[Jarrett Sung 3B]

All the half-life equations are based off the order equations on the equation sheet. Know which integrated equation goes with each order, and you can easily find the half-life equation.

[Sarah Hernandez 1F]

if it helps, on the Constants and formula sheet the half life for the first order is on the third from the bottom row of equations, second in the second from the bottom, and zero order is the second equation on the very bottom of the sheet, all denoted with t1/2

[Manseej Khatri 2B]

Hi. To find the half lives for each order reaction, you can use the integrated rate law. For example for zero order [A]/2 = -kt + [A]. Solving for t gives the half life. You can do the same for first and second order using their respective equations.

[Neha Mukund]

In order to find the half life of a reaction, you use these equations:
First order is t=.693/k, 2nd order is t=1/k[o], and Zero order is t=A[o]/2k

[Emma Goellner 2I]

For a first order reaction, t1/2=0.693/k
For a second order reaction, t1/2=1/k[A]o
For a zero order reaction, t1/2=[A]o/2k

[305561744]

1st order reactions use t1/2=0.693/k, 2nd order reactions use t1/2=1/k[A]o and 3rd order reactions use t1/2 = [A]o/2k

[Arjan G 2H]

Hi! For the half-life of a first-order reaction, you would use the equation 0.693/k, For the half-life of a second-order reaction, you would use the equation 1/k[A]0, where [A]0 is the initial concentration of the reactant. For a zero-order reaction, you would use the equation [A]0/2k. I hope this helps!

[Albert Chen 1G]

Depending on the order, there are certain equations that can be derived from the integrated rate laws.
First order t 1/2 = 0.693/k
Second Order t1/2 = 1/(k[A]o).
Zero order t1/2 = ([A]o)/(2k)

These can all be found on the equation sheet.