Ch. 19 nuclear chem **test** [45 points] honors Chemistry

For problems involving calculations, show your work in an organized manner, include any relevant equation (or formula and conversion factor(s)), put the proper units in your calculations / answer, and have the proper number of significant figures in your answer.

**Academic Honesty**: The answers on this test are my own and I am using only the allowed set of notes as described in the syllabus. I have not discussed the test questions with anyone before or during the test nor have I seen the test questions prior to the exam. If you violate any of the preceding items or do not sign, your semester grade is a F.

Signature: ___________________

1. Fill-in the blank; write the nuclear equation describing the following (hypothetical ?) nuclear reaction. [15 points]

a. the alpha decay of ^{235}Th: _____________________________________

b. the positron emission of ^{45}Ca: __________________________________

c. The (spontaneous) fission of ^{235}Ra involving ^{140}Ba: ______________________________

2. A hypothetical radioactive isotope took 5**.**0 days to go from 25**.**0 mCi to 20**.**0 mCi; Ci = Curie = 3**.**7 * 10^{10} isotopes disintegrate per second. A sample originally contained 125 nanomoles of this isotope; currently there is 75**.**0 nanomoles of the isotope. [15 points]

a. What is the isotope’s decay constant ?

b. What is the isotope’s half life ?

c. What is the age of the sample ?

3. Describe the basis of the atomic bomb; include / define the terms, critical mass and chain reaction in your response. [15 points]