posted by Anonymous .
how many grams of hydrogen make up 3.5 moles of glucose C6H6O6?
a 1.7g b 3.5g
c21.0g d 101.5g
You should calculate it by using the percentage by mass of the hydrogen atoms.
3.5mole of glucose is
ans is c.
you should know the formular to calculate all the question of the chapter of 'Reacting masses'.
eg. mass / molar mass=no of mole
no of mole*avagadros=no of particles
...and so on..
But since in each mole of the glucose, there's 6 moles of H atoms. So isn't it easier to just use 3.5 times 6?
my ans is just to show him the logic of calculate the chapter of reacting mass.and i agree that your method is absolutely good for MC question.
I would argue that this is a poor question because of the typo and poor wording. First, glucose is C6H12O6 so the molar mass is 180 and not 174. So the 3.5 moles glucose will provide 3.5 x 6 = 21 moles of H ATOMS. But due to poor wording in the problem, when I'm asked for moles hydrogen, that means moles H2 so I would have divided the 21 by 2 to obtain 10.5 moles H2 and that isn't one of the answers. The problem would be better to ask for moles hydrogen ATOMS. Then everyone knows what the problem is asking.