# Half Life Lab

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Great Basin College AMS 320 LAB 9 Objective In this lab we will perform an investigation to determine the half-life of a radioactive isotope Ba-137m. Introduction No other facet of chemistry has captured the attention of people in the latter half of the 1900s as the field of radiation. From the discovery of x-rays in 1900 to the destructive power of atomic weapons, we have seen a history that is very interesting. As discussed in class lecture, some atoms are unstable. Some will change into another element if given enough time. Consider the element carbon-essential for all forms of life on our planet. For the most part the carbon atoms in your body are the stable form carbon, C-12. A very small amount, one atom out of every 10, however,…show more content…
The sample size does not matter because this statistical process. Not all atoms change at once but for the most part half of the will eventually change into another element to isotope within the half life time period. The units of half-life are time and can be anything from seconds to millions of years. The uranium isotope U-238 has a half-life of approximately 4.4 billion years. Rodan-222, a radioactive isotope sometimes fund in people’s basements has half-life of then 4 days. The shorter the half-life, the active appearing the atom is. For example, a test tube containing a gram of Rn-222 will cause a Geiger counter to click a raster rate then a gram of U- 238 because more atoms are changing per second. In our lab we will calculate the half-life of Ba-137m. This metastable radioactive isotope has a half-life of less than 5 minutes and is made from the radioactive decay of Cs-137 in a mini-isotope generator. Radioactive Ba-137m decays it turns into the non-radioactive…show more content…
This is easily done by noting the counts an every minute and subtracting the previous count. The counter will keep adding just as odometer in a car adds what you have driven. So that you can plot a value for t=0, we will actually start our data at t=-1 minute. This will not change our results at all because we can start the counting anywhere we want – the shape of the will still be the same because the time constant is a fixed value for a given radioactive material. When you have generated a list of the activity as a function of time, do not forget to adjust this number by deducting the background count for each value because it would not be fair leaving it in. we will determine this in class by letting the Geiger counter count without the Ba-137m present. Plot this adjusted value o activity as a function of time starting at t=0. Do not start a t=-1 minute. Observations Time (minutes) | Activity (clicks) | Activity as a function of time | Activity as a function of time minus background activity(26) | 0 | 0 | 0 | 0 | 1 | 6414 | 6414 | 6388 | 2 | 11604 | 5190 | 5164 | 3 | 15796 | 4192 | 4166 | 4 | 18975 | 3179 | 3153