Good Morning and welcome to Chemistry.<\/p>\n\n\n\n
We’ve been talking about the mole the last few days. Today, we are continuing with the mole theme and asking you to calculate the %composition of a substance. You’ll need a calculator and a periodic table.<\/p>\n\n\n\n
For example: Water’s molar mass is 18 grams.<\/p>\n\n\n\n
O = 16 g (The periodic table says 15.999 g, so we can do a little rounding)<\/p>\n\n\n\n
H = 1 g x 2 = 2 g<\/p>\n\n\n\n
Add 16+2 and the molar mass of water is 18 grams.<\/p>\n\n\n\n
The percent by mass is {(mass of one element in the compound)\/(molar mass of total compound)} x 100<\/strong><\/p>\n\n\n\n (16\/18) * 100 = 88.9% Oxygen<\/p>\n\n\n\n (2\/18) * 100 = 11.1% Hydrogen. <\/p>\n\n\n\n They percentages should add up close to 100%.<\/p>\n\n\n\n I’d like you to find the percent by mass of each element in the following substances:<\/p>\n\n\n\n A. Aluminum Sulfate (see yesterday’s work for the formula)<\/p>\n\n\n\n B. Phosphoric Acid (H3<\/sub>PO4<\/sub>)<\/p>\n\n\n\n C. Calcium Chloride, CaCl2<\/sub><\/p>\n\n\n\n D. Ethane C2<\/sub>H6<\/sub><\/p>\n\n\n\n E. The mineral Ilmenite, FeTiO3<\/sub> (Note: it contains Titanium)<\/p>\n\n\n\n Please show all work on paper and send a picture of your work to me in Remind.<\/strong><\/p>\n\n\n\n Thanks,<\/p>\n\n\n\n Stay healthy and Stay Breezy.<\/p>\n\n\n\n T. Brown<\/p>\n","protected":false},"excerpt":{"rendered":" Good Morning and welcome to Chemistry. We’ve been talking about the mole the last few days. Today, we are continuing with the mole theme and asking you to calculate the %composition of a substance. You’ll need a calculator and a … Continue reading