Question Details	Asked By	Asked On
Stoichiometry--need to translate your responses into DImensional Analysis	erica2323	05/06/05
Hi- I asked three Stoich questions yesterday and you responded to two of them. Raridon to all three-however, We are taught to use something like this: Mass Given x Mol Given/ x Mol of Wanted/ x Mass Wtd/ (in Problem) Mass Given Mol Given Mol Wtd (mole ratio) I need to know how to solve the questions I asked using this. I can't translate your responses into this.... Dimensional Analysis. Thanks!
Answered By		Answered On
matrix		05/09/05
You need to understand the steps in doing reactions and not merely plugging numbers into a magic formula. My answers are consistent with dimensional analylis procedures. First, always write a correctly balanced equation for your problem.The numbers in front of the chemical formulas tell you the number of moles required of each reagent. For example in one of your problems, CH4 + 2 O2 ----> CO2 + 2 H2O This tells you that if you burn one mole of methane you will obtain one mole of carbon dioxide and two moles of water and will require two moles of oxygen. In your problem you obtained 25.0 g of CO2. This is 25.0g/44.0g/mole = 0.568 moles of CO2. Since one mole CH4 gives one mole of CO2,then to make 0.568 mole of CO2 you need 0.568 mole of methane. 0.568mole x 16.0g/mole = 9.09g of methane Also from equation you know that the reaction requires two moles of oxygen for every one mole of methane. 0.568 x 2 = 1.136 moles of oxygen are needed. 1.136 moles x 32.0 g/mole = 36.4 g of oxygen.

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