Question #f374d

1 Answer
Apr 3, 2016

Answer:

#"7.7 moles"#

Explanation:

The idea here is that you need to use the molar mass of elemental hydrogen to calculate how many moles you have in that #"93-g"# sample, then use the mole ratio that exists between glucose and hydrogen to find how many moles of glucose would contain that many moles of hydrogen.

So, hydrogen has a molar mass of #"1.00794 g mol"^(-1)#, which means that one mole of hydrogen has a mass of #"1.00794 g"#. In your case, you will have

#93 color(red)(cancel(color(black)("g"))) * "1 mole H"/(1.00794color(red)(cancel(color(black)("g")))) = "92.267 moles H"#

Now, take a look at a molecule of glucose, #"C"_6"H"_color(red)(12)"O"_6#. You can say that one mole of glucose, which is simply a very large collection of molecules of glucose, will contain

  • six moles of carbon, #6 xx "C"#
  • twelve moles of hydrogen, #color(red)(12) xx "H"#
  • six moles of oxygen, #6 xx "O"#

This means that #92.267# moles of hydrogen can be used to make

#92.267color(red)(cancel(color(black)("moles H"))) * ("1 mole C"_6"H"_12"O"_6)/(color(red)(12)color(red)(cancel(color(black)("moles H")))) = color(green)(|bar(ul(color(white)(a/a)"7.7 moles C"_6"H"_12"O"_6color(white)(a/a)|)))#

The answer is rounded to two sig figs, the number of sig figs you have for the mass of hydrogen.