March 25th-26th

Learning Goal: I can calculate the % composition of a substance Notes: Please watch the videos below to help you in your assignment

https://www.youtube.com/watch?v=JqKEaPmNFLg

For example: Water’s molar mass is 18 grams. O = 16 g (The periodic table says 15.999 g, so we can do a little rounding) H = 1 g x 2 = 2 g Add 16+2 and the molar mass of water is 18 grams. Formula: The percent by mass is {(mass of one element in the compound)/(molar mass of total compound)} x 100 (16/18) * 100 = 88.9% Oxygen (2/18) * 100 = 11.1% Hydrogen.

Assignment: Find the percent composition of the elements in the following compounds:

A. Aluminum Sulfate (see yesterday’s work for the formula)

B. Phosphoric Acid (H3PO4)

C. Calcium Chloride, CaCl2

D. Ethane C2H6

E. The mineral Ilmenite, FeTiO3 (Note: it contains Titanium)

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