• shenzys
In summary, the half life of sodium pertechnate is 6.02 hours based on the given measurements and using the equations ln A = ln A0 -lamda*t and half life = ln2/lamda.

## Homework Statement

A sample of sodium pertechnetate injection was found to have an activity of 51439 counts per minute (cpm). The sample was measured again exactly after 8 hours and found to have an activity of 20476 cpm. Calculate the half life of sodium pertechnatate.

## Homework Equations

A = A0 e^-lamdat
ln A = in A0 - lamdat
half life = ln2/lamda

## The Attempt at a Solution

ln 20476 = ln 51439 -lamda * 8
9.927008748 = 10.84815192 - lamda * 8
0.9150875487/8 = -lamda
lamda = 0.1143859436

half life = 6.06 hours

Is this correct? I think I did the algebra a bit wrong but the answer of 6 hours sounds about right... can anyone help please...thanks.

Okay I went wrong... I now get the answer of 6.02 hours...

Your calculations and answer appear to be correct. It is always a good idea to double check your algebra when solving equations, but your answer of 6 hours for the half life of sodium pertechnetate seems to be accurate based on the given information. It is also important to note that the half life of a radioactive substance can vary slightly depending on the conditions and environment in which it is measured. Therefore, it is always best to confirm your results with multiple measurements. Keep up the good work!

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