A sample of a substance containing only magnesium and chlorine was tested in the laboratory and was found to be composed of 74.5% chlorine by mass. If the total mass of the sample was 190.2 grams, what was the mass of the magnesium?

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Answer 1 · 2016-11-06T15:20:23

#"Mass of magnesium"# #=# #25.5%xx190.2*g=48.5*g#

In a binary compound, #XY#, if #%X# is given, then, clearly, #%Y=100-X%# with respect to mass.

So we take that figure and multiply it by the mass of the sample to give under #50* g#.

Note that you could use the data given to give an empirical formula for the compound.