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In this video, we want to find the percent by mass of aluminum in aluminum sulfate, al2, so4, 3.
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So the percent by mass of a component, in this case aluminum, is the ratio of the mass of that component, so the total mass of aluminum, over the total mass of all of aluminum sulfate, times 100 to turn the decimal into a percent.
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So if you look on the periodic table, the molar mass of aluminum is 26 .98, grams per mole.
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And there's two of them in the formulas.
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That's two times 26 .98 on the top.
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And our total mass is, well, we can just calculate the molar mass.
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So we have two times 26 .98 for aluminum.
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And then we distribute this three...