CARBON DIOXIDE RELEASED IN THE ATMOSPHERE This activity is self-contained. You will learn more about climate change in the following module, lmtyozr do not need any other information, besides what's available here, to complete this work. Keep in touch with me ifyon need help. READ the footnotes for additional information! I In this exercise you will use real data on the atmospheric concentration of C03 gathered since the 1959 at the Mauna Loa observatory (MLO) in Hawaii, to calculate how much CO; has been released by human activities since then. The Mauna Loa Observatory has been collecting carbon dioxide data since 1958, when Dr. Keeling (who had developed an instrument to measure C02 at Caltech) started gathering the data. The location was selected in order to eliminate the interferences that previous measurements had found in the US and Scandinavia (mainly originated by the local in?uence of growing plants and exhausts from motors). The MLO is far away ?'om large inhabited centers (hence eliminating the interferences due to vehicles), and the air is constantly "cleaned" by winds that bring fresh one from the Central Paci?c (this eliminates any interference from the vegetation present on the island). The same winds eliminate any interference from COZ emitted by the volcano. Follow these step by step instructions to complete the activity (DO NOT perform the calculations by hand and then insert the numbers in excel. YOU MUST use excel formulas otherwise you will not receive full credit for your work): 1. Download the excel ?le with the data using the link provided in the main page for this lesson. You will notice that contains data in two columns: Year and Annual (PPM). The years from 2016 to 2039 are blank. This is on purpose (you will have to use those years later in the assignment); 2. Convert the Annual concentrations of C02 from PPM (parts per millions) to Gigatons of C02 (and carbon C) in the atmosphere for each year. a. To perform this conversion first you will need to consider that each PPM of C02 recorded at Mauna Loa in a particular year can be assumed to represent one million (106) molecules to C02. Before we use the number of PPM recorded in one year in our calculations we need to "scale it down" - so that each PPM represents only one molecule. Insert the results of this calculation in column C (PPM Reduced). Notice that the cells in column C have been formatted to show eight decimal digits (if you only see zeros, then your formatting is wrong and you need to reformat the cells A ). Leave blank all the cells that correspond to the years (from 2016 to 2039) where you have no data. b. Now we can use the numbers calculated above to ?gure out how many molecules of C02 are in Earth's atmosphere in a particular year, and how much is their total weight in grams. First we need to remember the defmition of mole in chemistry 2: "One mole represents the weight in grams of a standard number i of molecules (or atoms) of a certain substance. The weight of one mole is the same as the molecular (or atomic) weight of the substance being 1 Since each PPM of C02 recorded at Marina Loa represents one million molecules of C02 in the atmosphere, if taken as is, the "importance" of this number would be overestimated (i.e. we need to make this number smaller). At the same time this calculation will produce a number that represents moles of C02 (for the purpose of the calculations at point b). 2 This applies to each occurrence of "I only see zeros in the cell". Also if a cell displays "##1##" it means it's not large enough to see the number, and you need to change its width. 3 This is not the strictly standard de?nition that you can ?nd in chemistry textbooks. I rewarded it so that it's more useful for this assignment. 4 This standard number is called the Avogadro's number (6.023 x 1023). You will NOT need this number for your calculations. -1-

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