Question #7908b

1 Answer
Jun 12, 2017

65.065.0 "g N"_2g N2

Explanation:

Any time you want to convert between moles and grams of a substance, you must know that substance's molar mass, which is the mass of one mole of that substance. (One mole is equal to Avogadro's number (6.022xx10^236.022×1023) of individual particles/molecules of that substance.)

To find the molar mass of a nitrogen molecule, we'll first realize its chemical formula, which is "N"_2N2.

Most periodic tables list the molar masses (same number as atomic mass) of all the elements under their chemical symbol. For nitrogen, the molar mass is 14.01"g"/"mol"14.01gmol, that is, one mole of pure nitrogen atoms has a mass of 14.0114.01 grams.

Since there are two nitrogen atoms per nitrogen molecule, the molar mass of "N"_2N2 is double that of elemental nitrogen:

2 xx 14.01"g"/"mol" = color(red)(28.02"g"/"mol"2×14.01gmol=28.02gmol

Now, we can use dimensional analysis to convert between moles and grams of "N"_2N2:

2.322.32 cancel("mol N"_2)((color(red)(28.02"g N"_2))/(1cancel("mol N"_2))) = color(blue)(65.0 color(blue)("g N"_2

rounded to color(purple)(3 significant figures, the amount given in the problem.

Thus, 2.32 moles of pure nitrogen gas has a mass of color(blue)(65.0 grams.