## anonymous one year ago Half-Life reaction help?

1. anonymous

The purpose of this hands-on lab is to model the concept of half-life using a sample to represent radioactive atoms. Materials 200 M&M® candies, pennies, or other small candy/item with two distinct sides shoe box or other small box with a lid Procedure Place 200 candies in the shoe box, lettered sides up. The candies will stand for atoms of a hypothetical radioactive element. Cover the box and shake it vigorously for three seconds. This is one time interval. Remove the lid and take out any candies (atoms) that have that are now showing lettered sides down. These candies represent the atoms that decayed during the time interval. Count and record in a data table the number of decayed atoms and the number of remaining, not decayed, atoms. Continue repeating steps two and three until all atoms have decayed or you have reached 30 seconds on the data table. Repeat the entire experiment (steps 1–4) a second time and record all data. Data and Observations Create and complete a data table, like the one below, for each trial. Time (seconds) | Radioactive atoms remaining (not decayed) | Atoms decayed 0 | 200 | 0 3 | 107 | 93 6 | 51 | 56 9 | 29 | 27 12 | 18 | 11 15 | 7 | 11 18 | 6 | 1 21 | 4 | 2 24 | 2 | 2 27 | 2 | 0 30 | 2 | 0 Calculations Time (seconds) | Radioactive atoms remaining (not decayed) | Atoms decayed 0 | 200 | 0 3 | 113 | 87 6 | 46 | 41 9 | 31 | 15 12 | 16 | 15 15 | 8 | 8 18 | 5 | 3 21 | 3 | 2 24 | 1 | 2 27 | 1 | 0 30 | 0 | 1

2. anonymous

Determine the average number of atoms remaining (not decayed) at each three-second time interval by adding the results from the two trials and dividing by two. 3 = 163.5 6 = 48.5 9 = 30 12 = 17 15 = 7 18 = 5.5 21 = 2.5 24 = 1.5 27 = 1.5 30 = 1 Create a table that compares time to the average number of atoms remaining at each time interval.

3. anonymous

After how many time intervals (shakes) did one-half of your atoms (candies) decay? Trial 1: It took 8 Trial 2: 6 shakes What is the half-life of your substance? <-------------------(This I need help with)

4. anonymous

The answer is B

5. cuanchi

@alante in the first shake you went from 200 to 107-113 remaining atoms, this is almost 50% of the original amount . This will be the 1/2 life of your atom, is the time that takes the initial amount decrease in 1/2 of the original value.

6. anonymous

@Woodward would you mind helping me with this? Cauanchi is offline. I'm not sure if almost half would cut it, especially with it not being something like 101, 107 seems to high to cut it as "almost"

7. anonymous

too*

8. anonymous

I think that's part of the fun of the experiment. It's not exact, but that's how it was and we must accept the deviation of reality from the theory. So we didn't have exactly half, but it is not too far away. $\frac{107}{200} *100\% = 53.5\%$ So you expected 50% to be left, so instead you had 3.5% more. I don't think that's that bad but I guess this is kind of subjective. It's certainly much closer than 60% which would make me start to wonder. I don't know if that really answers your question or not...?

9. anonymous

See, that's the confusing part. This part of the lesson didn't explain anything along the lines of "close enough" so, I expected it to want something exactly 50%. There's more to follow, but I still need an understanding on what the half life is

10. anonymous

Not to mention there's also the other trial I needed to do where 113 is halflife being 56% of the 200

11. anonymous

would you mind if I were to just ask for the next questions? I'll eventually figure it out

12. anonymous

I'll just post these xD If the half-life model decayed perfectly, how many atoms would be remaining (not decayed) after 12 seconds? If you increased the initial amount of atoms (candies) to 300, would the overall shape of the graph be altered? Explain your answer. Go back to your data table and for each three-second interval divide the number of candies decayed by the number previously remaining and multiply by 100. Show your work. The above percentage calculation will help you compare the decay modeled in this experiment to the half-life decay of a radioactive element. Did this activity perfectly model the concept of half-life? If not, was it close? Compare how well this activity modeled the half-life of a radioactive element. Did the activity model half-life better over the first 12 seconds (four decays) or during the last 12 seconds of the experiment? If you see any difference in the effectiveness of this half-life model over time, what do you think is the reason for it?

13. anonymous

Sure you can try, I'm a bit distracted at the moment so no guarantees though! Half-life is an amount of time. So for instance 10 seconds or 5,730 years are possible values for a half-life. So now that we know that it's a length of time, what's supposed to happen during this time? Well during this time, half of what you started with will decay! So let's say we have 50 pounds of some substance that has a half-life of 10 seconds. Then that means 10 seconds later there's only about 25 pounds left! If we wait another 10 seconds (20 seconds in all) we will only have about 12.5 pounds of it left! It disappears quite rapidly, and in fact that's because this is a form of exponential decay.

14. anonymous

I understand, I appreciate any help man. Alright well 107 is at 3 seconds, but a "close enough" half is with 51 at 6 seconds. then we have 29 at 9 seconds. But what does this prove to a half life?

15. anonymous

I'm still really confused ._.

16. abb0t

that the whole decay process is not a constant rate half-life is just a description whence the amount is halved (or close) of the original number of species from when the decay process started at a given time.

17. anonymous

but it ask what the half life is to the substance? There's 2 trials and I'm still confused on what exactly I do to find the half life of that substance. Do I use both data? Separate data for 2 substance?

18. abb0t

it asked you to use both data then divide by two

19. anonymous

But that was for the first question. I also don't have substances for question 3 to use nor any weight. I know we can use the 2 trials but it just isn't making since to me what to do with it. Is it as simple as putting 107 and 113 by 2? Or 3 for 3 seconds?

20. anonymous

I got kind of lazy with the rest of the questions, sorry about that. I'm still not 100% sure of what to do on number 3 though.

21. cuanchi