Radioactive decay lab: M&Ms®
- pour at least 40 M&Ms® into a jar, close the lid and mix
- pour the M&Ms® out onto a plate, and count the total number
- remove any M&Ms® that have the logo face up
- count again
- repeat #1 above
- graph your results, with the X-axis as number of tests and Y-axis as number left after each removal
- what does the X-axis represent?
- what does the Y-axis represent?
Some math you will need to know:
A half life is the time it takes for half of something to go away.
In radioactivity, we use the formula: amount left = starting amount x (1/2)^n. where n is the number of half lives:
Sample problem:
Starting with 128 grams of unobtainium, which has a half life of 10 minutes, how much will be left after:
10 minutes
20 minutes
60 minutes
15 minutes (tough one, make sure you know how to use your calculator in real mode, not "hello Kitty" mode
You can also write the formula as: amount left = starting amount/2^n
Questions:
- What is similar and/or different between U 234/92 and U 238/92?
- How many protons, neutrons and electrons in each?
- Would you expect this to be radioactive?
- A news announcer says:”Iodine 131 has a half life of 8 days, so it will all be gone in just 16 days”. What is wrong with this?
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