Question

Question #f374d

Answer 1

`"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.