YouTube Upload – Chemistry / Empirical Formula Calculations Set 2

Chemistry_UploadGreetings All. I have uploaded the second set of problems for the Empirical and Compound Composition calculation set. You can find them here.

My apologies for the continued sound of my voice (still have a cold), and missing the fact that on this video set I’ve cut off half the bottom line of each set. Duh.

This set reinforces the importance of significant figures. For the second problem, as example, if the numbers in the ratio 1:2.67 had been multiplied by 2 to get 2:5.34 and these numbers had been rounded off to give 2:5, the wrong formula would have been obtained. This would not have been justified because it would have assumed an error of 34 parts in 500 in the analysis of oxygen. The given weight of oxygen, 0.449 grams, indicates a possible error of only a few parts in 500, not 34. Using 3 as a factor calls for a rounding in only a few parts in 500, which is more consistent with the analysis of oxygen.

Next week: Physics problems relating to friction. See you at the white board.


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