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Need help with UMUC NSCI 101/103 Radioactivity UMUC NSCI 101/103 Lab 7: Radioact

ID: 1586877 • Letter: N

Question

Need help with UMUC NSCI 101/103 Radioactivity

UMUC NSCI 101/103

Lab 7: Radioactivity

INSTRUCTIONS:

·On your own and without assistance, complete this Lab 7 Answer Form and submit it via the Assignments Folder by the date listed on your Course Schedule (under Syllabus).

·To conduct your laboratory exercises, use the Laboratory Manual that is available in the classroom. Laboratory exercises on your CD may not be updated.

·Save your Lab 7 Answer Form in the following format: LastName_Lab7 (e.g., Smith_Lab7).

·Submit your document in a Word (.doc or .docx) or Rich Text Format (.rtf) for best compatibility.

Experiment 1: Estimating Half-Life

Table 2: Half-Life Experimental Results

Total number of atoms:

Trial

Number of decayed atoms

Average

Percentage of decayed     atoms                                   (from original number)

1st Round

2nd Round

3rd Round

1

2

3

4

5

6

7

8

9

10

Questions

What is meant by the term half-life?

At the end of two half-lives, what percentage of atoms (Skittles™) have not decayed? Show your calculation.

Using your data, graph the number of undecayed atoms vs. trials below to show when 1/2, 1/4, 1/8, and 1/16 of your Skittles remain (use the values next to the boxes you put checks next to in Step 8 of the procedure).

How would the graph change if 20 Skittles were used in this experiment?

If 1/8 of a radioactive element remains after 600 years, what is that element’s half-life?

Total number of atoms:

Trial

Number of decayed atoms

Average

Percentage of decayed     atoms                                   (from original number)

1st Round

2nd Round

3rd Round

1

2

3

4

5

6

7

8

9

10

Explanation / Answer

1) The half-life of a radioactive isotope is the time that it takes for a radioactive isotope (meaning that it is unstable and will emit particles and energy) to decay to half its original amount. For example, you have 18 g of fluorine-18. If its half life is 40 days (which in reality, it probably isn't), then after 40 days, you'll only have 9 g of that element. The 9 g of fluorine-18 that was decayed in the forty days is now another element.

2) At the end of two half-lives, 25 percentage of atoms have not decayed.

As at one half-year, it remains 50% then after second half life it again decay 50 % of remaining i.e. 25%

Hence At the end of two half-lives, 25 percentage of atoms will remain.

3) You didn't post a picture of the graph.

4) If 20 Skittles were used in this experiement, you would have only gotten about 5 trials out of it. Because you wouldn't want to try to account for partial Skittles.

5) we have, N = No e^(-kt)
No/8 = No e^(-k x 600)
k = 3.4657 x 10^-3
Half life = 0.693/k = 199.957 years