How many grams are in 3.8 m moles of #CH_4#?

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Answer 1 · 2015-12-06T19:28:21

One mole of methane has a mass of 16.0 g.

In #3.80# #mmol#, there are #3.80# #xx10^(-3)##cancel(mol)# #xx# #16.0*g*cancel(mol^-1)# #=# #??# #g#.

Answer 2 · 2015-12-06T19:57:41

#"3.8 mmol CH"_4"# has a mass of #"0.061 g"#.

The molar mass (mass of one mole) of #"CH"_4"##=##(1xx12.0107"g/mol")+(4xx1.00794"g/mol")="16.04246 g/mol"#

Convert 3.8 mmol to mol.

#3.8cancel"mmol"xx(1"mol")/(1000cancel"mmol")="0.0038 mol"#

Multiply moles times molar mass.

#0.0038cancel"mol CH"_4xx(16.04246"g CH"_4)/(1cancel"mol CH"_4)="0.061 g CH"_4"# (rounded to two significant figures)