 Top

Half Life Calculator
Top
The half life (t1/2) is the time required to get half-way to equilibrium from some given reaction conditions.The half life is used most often for nearly reversible reactions, in which case it is the time required for half the reactant to be consumed. The half life is always inversely proportional to k, but its dependence on [A]o depends on the order of the reaction.

The formula for Half-life is expressed below.

$T_{\frac{1}{2}} = \frac{T \times log2}{log\frac{Amt\ B}{Amt\ E}}$
Where
• T1/2 = Half Life
• T = Elapsed Time
• Amt B = Beginning Amount
• Amt E = Ending Amount

Steps for Half Life Calculator

Step 1 :

Read the problem carefully and list out the values given.

Step 2 :

Substitute all the given values in the corresponding formula to find out the unknown value.

$T_{\frac{1}{2}} = \frac{T \times log2}{log\frac{Amt\ B}{Amt\ E}}$

Problems on Half Life Calculator

1. The concentration of the beginning amount is 0.229 and the concentraton of ending amount is 0.282. Calculate the t1/2 in which the elapsed time is 280 sec.

Step 1 :

Given data

Beginning amount = 0.229

Ending amount = 0.282

T (elapsed time) = 280 sec

Step 2 :

Substitute the values in the formula to find out the t1/2.

$T_{\frac{1}{2}} = \frac{T \times log2}{log\frac{Amt\ B}{Amt\ E}}$

$T_{\frac{1}{2}} = \frac{280 \times log2}{log\frac{0.282}{0.229}}$

T1/2 =  932.25 sec

The answer is T1/2 =  932.25 sec.

2. For a radioactive decay the half life is given as 438 sec and the concentration of the beginning amount is 0.864 and the concentration of the ending amount is 0.897. Calculate the time elapsed in the decay.

Step 1 :

Given data

T1/2 = 438 sec

Beginning amount = 0.864

Ending amount = 0.897

Step 2 :

Substitute the values in the corresponding formula.

$T_{\frac{1}{2}} = \frac{T \times log2}{log\frac{Amt\ B}{Amt\ E}}$

$438 = \frac{T \times log2}{log\frac{0.897}{0.864}}$

T =  23.686 sec