How many grams of carbon are present in 10g of CH4?

1 Answer
Truong-Son N.
Jul 20, 2018

The molar mass of #"CH"_4# will be needed:

#M_m = "12.011 g/mol C" + 4 cdot "1.0079 g/mol H"#

#=# #"16.0426 g/mol"#

The molar mass of #"C"# is #"12.011 g/mol"#, so it makes up #"CH"_4# as:

#12.011/16.0426 xx 100% = 74.87%# by mass

Because percent by mass is relative, we can choose any quantity of particles in setting up this ratio. I chose #"1 mol"# of #"CH"_4#, so that it has #"1 mol C"#.

Therefore, #"16.0426 g"# of #"CH"_4# would have #"12.011 g C"#, and so, in #"10 g CH"_4#, there would be

#0.7487 xx "10 g CH"_4 = color(blue)("7.487 g C")#

If you found that there was #"13.357 g"# of #"C"#, it would not make physical sense. Why?

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