Homework #1 Problem Set DECAY KINETICS, EQUILIBRIUM, DATING
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1. If 140Ba is freshly separated from a fission product mixture and found to contain 125
milliCi, (a) what is the activity of 14°La that will grow into the sample in 17.2 hr? (b)
What is the maximum activity of 140La that will ever be present in the sample, and (c)
when will it occur?
a. A=
Ti
T₂-T2
x Ap * (e-Azt – e-dzt)
A=
12.75 d
12.75 d -1.678
x 125 mCi x (e 306 h*17.2 h
In2
In2
e 40.272 h
x
17.2 ") = 31.38 mCi
b. A=
12.75 d
12.75 d-1.678
Inz
x 125 mCix (e 12.75 d*
x 5.65 d
In2
e 1.679 d
a *5.65 d) = 91.3 mci
c. tm = 1.4427 x
12.75 x 1.678 12.75
X In
12.75-1.678 1.678
= 5.65 days
the wa
2
A short-lived radioisotone

- calcium has greater affinity to bond with electron receptors than hydrogen does and hence, it has the ability to replace hydrogen in most of its compounds.

- lithium has 2 valence electrons in the product because it can make only 1 bond with hydrogen. beryllium has 4 valence electrons in the product because it can only make 2 bonds. it has fewer electrons than neon and can react with electron donors. each hydrogen has 2 valence electrons, the same as helium.

- the covalent bond formed between carbon and hydrogen is polar because carbon is more electronegative than hydrogen and it attracts the bonded electron pair closer to itself, thus giving hydrogen a partial positive charge.

- a hydrogen bond is a relatively weak bond that hydrogen atoms make with the electronegative atoms nitrogen, oxygen or fluorine.

so the best choice is a.) 2 calcium (ca) atoms

what is the question?