Question #8d45c

Assuming that the question is correct, you can convert the number of moles of oxygen gas to grams by using its molar mass. Oxygen gas has a molar mass of #"31.9988 g mol"^(-1)#, so you can say that #1# mole of oxygen gas has a mass of #"31.9988 g"#.

This means that your reaction consumed

#11.52 color(red)(cancel(color(black)("moles O"_2))) * "31.9988 g"/(1color(red)(cancel(color(black)("mole O"_2)))) = color(darkgreen)(ul(color(black)("368.6 g")))#

The answer is rounded to four sig figs, the number of sig figs you have for the number of moles of oxygen gas that took part in the reaction.

#color(white)(aaaaaaaaaaaaaaa)/color(white)(a)#

Seeing how this is supposed to be a stoichiometry problem, I think that you were actually looking for the mass of nonane that took part in the reaction.

You know by looking at the balanced chemical equation that the reaction consumes #9# moles of oxygen gas for every #1# mole of nonane that takes part in the reaction, so you can start by using this mole ratio to find the number of moles of nonane that reacted.

#11.52 color(red)(cancel(color(black)("moles O"_2))) * ("1 mole C"_9"H"_20)/(9color(red)(cancel(color(black)("moles O"_2)))) = "1.28 moles C"_9"H"_20#

Now, to convert the number of moles of nonane to grams, use the compound's molar mass.

Nonane has a molar mass of #"128.2 g mol"^(-1)#, which means that #1# mole of nonane has a mass of #"128.2 g"#.

You can thus say that your reaction consumed

#1.28 color(red)(cancel(color(black)("moles C"_9"H"_20))) * "128.2 g"/(1color(red)(cancel(color(black)("mole C"_9"H"_20)))) = color(darkgreen)(ul(color(black)("164.1 g")))#

Once again, the answer must be rounded to four sig figs.