Reference no: EM131177858

Lab: Radioactivity and Radiation Dry Lab

Overview (pgs. 311-312)

Read the Purpose, Background, Materials, and Safety First sections of Experiment 52 in the Prentice Hall Chemistry: Laboratory Manual.

Pre-Lab Questions

Complete the pre-lab questions for this lab and submit them to your instructor or online instructor.

Procedure (pgs. 312-313)

Read the procedures for Geiger counter measurements.

Observations (pgs. 314-315)

Data Table 1: Effect of Distance on Radiation Intensity
Distance from Source (cm)	Radiation Intensity (cpm)
4	228
2	883
1	3321

Transfer these measurements to the data sheet.

Data Table 2: Effect of Shielding on Radiation Intensity
Shielding Material	Radiation Intensity (cpm) Source: 14C Radiation type: β	Radiation Intensity (cpm) Source: 137Cs Radiation type: β, γ
none	1284	1462
paper	1140	1458
wood	862	1410
aluminum	412	1326
glass	363	1302
lead	24	1265
cotton fabric	1054	1445
plastic	1162	1452

Data Table 3: Effect of Time on Radiation Exposure (Source: 137Cs)
Time (min)	Total Counts
1	1368
5	6840
30	40800
60	81600

Analyses and Conclusions (pg. 316)

Answer questions 1 - 5 and "Going Further" in the lab manual using the data and observations provided above.

#1. A Geiger counter is used for the detection and measurement of all types of radiation: alpha, beta andgamma radiation. It consists of a pair of electrodes surrounded by a gas.

#3. Lead was the best shielding material.

4. When you double the distance from a radioactive source, the energy at that distance decreases by a factor of four. So the counts per minute should also decrease by a factor of four.

5. To a significant extent, yes. Radiation is not like poison, in that you can "consume" some and it can do damage to you later, at leisure. For the most part, radiation does its damage immediately (although the effects may only be felt over time), and it begins when you begin exposure, and then goes on until you stop. The longer you're exposed, the more damage. It's just like the fact that you get wetter the longer you stand in the rain. Generally, the harm radiation does harm you, if it is harmful at all, it's proportional to the total energy you absorb, and that is equal to the intensity of the radiation multiplied by the length of time to which you are exposed to it.

Develop a Hypothesis:

Based on the results of this lab, develop a hypothesis to explain why the radiation from the 14C source could be shielded more effectively than the radiation from the 137Cs source. What do your results suggest about the decay mode of each radioactive isotope?