5.2 P and Detecting Differences in Variable Quantities.3.3 Calculating Descriptive Statistics using Excel.3.1 Describing Quantities and Their Variation.Excel Reference and Statistics Manual Toggle Dropdown.Appendix A: Calculation Final Concentrations.3.1 Specific details regarding scientific writing.Scientific Literature Guide Toggle Dropdown.

Look at your calculated values for 50% and 75% loss. How long does it take for 75% to react? 300 seconds, 1000 seconds, or 80 seconds? How long does it take for 50% of the Ba137 to decay? (Approximately) 1000 seconds, 160 seconds, or 300 seconds? The half-life is represented by t1/2 in the graph. The importance of half-life in first-order reactions comes in when you go further because it takes the same amount of time to lose the first 50% as it does to lose the next 25%. If you start with 10 g of a substance, the half-life is the time it takes for only 5 g to remain. The half-life of a radioactive isotope is the time it takes for some amount of substance to decay to half of the original quantity. In this section, we will use the data from the videos to determine the half-life of Ba137. Please provide the time and counts for the first point. You have not provided any information on which point you have selected. Take a point on the exponential curve and record its time and counts: Note that the negative sign indicates that your calculated value is higher than the actual value.ģ. Percentage error = x 100 = -654.90% (rounded to two decimal places). The actual half-life of Barium 137m is 2.55 minutes, so the percentage error is: Half-life = (ln 2)/0.0006 = 1155.14 seconds or 19.25 minutes (rounded to two decimal places). You need to substitute the decay constant (l) from the equation you obtained in step 1. You have used the correct formula, Half-life= (ln 2)/l, but your calculation seems to be incorrect. It seems like you have done this correctly as you have provided the equation, R2 value, and decay constant. Now pick a second point that is at a time that is one half-life (according to your calculations) away, and record its number of counts. Half Life = 1115% Error _ Take a point on the exponential curve and record its time and counts. Compute your percentage error by comparing against the actual half-life of 2.55 minutes. Compute the half-life of Barium 137m by using the equation on the first page. What did I do wrong? This answer does not look correct.

Excel trendline equation wrong