Anyone able to help with my 1/2 Nuclear Physics question

[Adequace]

I'm having trouble understanding what to do even though I know how to use the formulas.

9kg of a 9.6kg Krypton-89 of is observed to decay 12.6 minutes. Determine its half life.

The wording of this sentence is a bit different from the others which throws me off

[dankfrank420]

Is the answer 189 seconds?

[Adequace]

Is the answer 189 seconds?

Yes it is! Do you mind showing me your working?

[dankfrank420]

Yes it is! Do you mind showing me your working?

9/9.6 * 100 = 93.75% --> So 93.75% has decayed, this means that 6.25% of the isotope has not decayed.

100% --> 50% --> 25% --> 12.5% --> 6.25%

Therefore we have had 4 half-lives to make 93.75% decay and have 6.25% remain.

12.6/4 = 3.15 minutes = 189 seconds.

[Adequace]

9/9.6 * 100 = 93.75% --> So 93.75% has decayed, this means that 6.25% of the isotope has not decayed.

100% --> 50% --> 25% --> 12.5% --> 6.25%

Therefore we have had 4 half-lives to make 93.75% decay and have 6.25% remain.

12.6/4 = 3.15 minutes = 189 seconds.

Thanks, did you use a certain formula? I sometimes have a problem of failing to interpret questions properly..

[dankfrank420]

Thanks, did you use a certain formula? I sometimes have a problem of failing to interpret questions properly..

Nope.

Nuclear physics in unit 1 is more about intuition than whacking numbers into a calculator. Just practise I suppose and you'll get it.