Visualizing The Reaction Of Methane With Oxygen Molecules

This animation shows that one molecule of methane reacts with two molecules of oxygen to produce one molecule of carbon dioxide and two molecules of water.

Notice that in the first frame of this animation there are four bromine molecules and two ethene molecules. Each of the ethene molecules reacts with one bromine molecule to form 1,2-dibromoethane. After the reaction is complete; that is, after the two ethene molecules have reacted, two bromine molecules and the two product molecules remain. Thus, this reaction mixture contained more bromine than was required to react with the ethene present. Or, to look at it somewhat differently, there were not enough ethene molecules to react with all of the bromine present. The ethene is the limiting reagent in this reaction mixture.

A 2.14 gram sample of an unknown that contains carbonate ion is weighed out and dissolved in water in an Erlenmeyer flask. This solution is then titrated with 0.100 molar hydrochloric acid using modified methyl orange is the indicator. The buret is read at the beginning of the titration and then again when the endpoint, the gray color, has been reached. A total of 35.03 mL of titrant were added. A few additional drops of titrant changes the color to purple.