The molar mass of #NO_2# is 46.01 g/mol. How many moles of #NO_2# are present in 114.95 g?

1 Answer
Jan 10, 2016

Answer:

#"2.498"#

Explanation:

A substance's molar mass tells you the mass of one mole of that substance.

In your case, nitrogen dioxide, #"NO"_2#, is said to have a molar mass of #"46.01 g/mol"#. That means that every mole of nitrogen dioxide will have a mass of #"46.01 g"#.

So, in essence, molar mass is simply a conversion factor between number of molecules and mass.

Since you need #"46.01 g"# of nitrogen dioxide in order to have one mole of the compound, it follows that #"114.95 g"# will contain

#114.95 color(red)(cancel(color(black)("g"))) * "1 mole NO"_2/(46.01color(red)(cancel(color(black)("g")))) = "2.49837 moles NO"_2#

Rounded to four sig figs, the number of sig figs you have for the molar mass of the compound, the answer will be

#n_(NO_2) = color(green)("2.498 moles")#