anonymous
  • anonymous
Half-Life reaction help?
Chemistry
  • Stacey Warren - Expert brainly.com
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schrodinger
  • schrodinger
I got my questions answered at brainly.com in under 10 minutes. Go to brainly.com now for free help!
anonymous
  • 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
anonymous
  • 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.
anonymous
  • 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)

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anonymous
  • anonymous
The answer is B
Cuanchi
  • 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.
anonymous
  • 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"
anonymous
  • anonymous
too*
anonymous
  • 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...?
anonymous
  • 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
anonymous
  • anonymous
Not to mention there's also the other trial I needed to do where 113 is halflife being 56% of the 200
anonymous
  • anonymous
would you mind if I were to just ask for the next questions? I'll eventually figure it out
anonymous
  • 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?
anonymous
  • 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.
anonymous
  • 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?
anonymous
  • anonymous
I'm still really confused ._.
abb0t
  • 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.
anonymous
  • 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?
abb0t
  • abb0t
it asked you to use both data then divide by two
anonymous
  • 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?
anonymous
  • 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.
Cuanchi
  • Cuanchi
@alante the questions follows one to another. You did one experiment with two trials. The result of your experiment is the average of the two trials. If you do more trials (we can said 100 trials), the result of your experiment will be the average of your 100 trials. In theory if you are careful enough in your technique the value is going to have a smaller experimental error if you repeat the trials many times than if you do just twice. The you should average the two values of the two trials (107+113)/2=110 Since the experiment choose each increment of time every 3 seconds, you dont know whats happen between the 0 and 3 or between 3 and 6 you assume that the relationship is linear. This is the smallest time lapse that you are able to measure in this experiment. Maybe under other conditions in a new experiment you can measure whats happen a shortest times. (this is not your issue now). So the question 3 is asking you at what time your initial sample is only 50% of the initial amount. You have only the measurements of time 0, 3, 6, 9, etc. You know that a time 0 you have 100% and at time 3s you have 55%, and at time 6s you have 24.25%. At what time you have 50% of your original sample? at 0, 3, 6? You can said that will be some time between 3 and 6 and you can add a second digit (uncertain) at your measurement and said 3.2s, or 4.3s, or anything between 3 and 6s. this value will be the half life of your atom.

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