between water (h2o) and hydrogen peroxide (h2o2), which has the highest percntage of hydrogen by mass?

Question

(if someone could tell me how they got their answer, that would be great) thanks in advance

Answer 1

Water...

Lets do this without even thinking about atomic weights.

Lets say you are making breakfast. One "H" will be a cup of cereal (some constant mass). One "O" will be a cup of milk (another constant mass).

If you have H2O, in your bowl, you will have two cups of cereal and one cup of milk. The total mass will be the mass of the two cups of cereal plus the mass of a cup of milk.

Now you have H2O2. You add two cups of cereal and two cups of milk. The total mass will be the mass of two cups of cereal plus the mass of two cups of milk.

Both "products" have two cups of cereal. The "water" has only one cup of milk while "Hydorgen Peroxide" has two cups of milk.

Since they both have the same amount of cereal, that means whichever has less milk will have the highest percentage of cereal by mass. Thus water has the highest percentage of hydrogen by mass

Hope this helps.

Answer 2

water because when comparing the two molecules which have the exact same amount of hydrogen, hydrogen peroxide has more additional atoms in a molecule. The mathematical breakdown is:
1 H = 1.0079 atm (atomic mass units or if that's confusing, for this explanation think of atm's as grams)
1 O = 15.9994 atm

So for water: 2 H + 1 O = H2O
Multiplying and adding masses together:
2*(1.0079 atm) + 1*(15.9994 atm) = approx. 18 atm

For hydrogen peroxide: 2 H + 2 O = H2O2
again multiplying and adding masses:
2*(1.0079 atm) + 2*(15.9994 atm) = approx. 34 atm

To find percentage by mass, take the total amount of H in each molecule (which is approx. 2 atm) and divide it by the total mass of each molecule:

(2 atm / 18 atm) * 100% = 11.11% H in water

(2 atm / 34 atm) * 100% = 5.88% H in hydrogen peroxide

So from that you can see that water has a higher percentage by mass of H than hydrogen peroxide.

Answer 3

H2O.
Think!
4 moles of H2O > 8 hydrogen and 4 oxygen(12 elements)
3 moles of hydrogen peroyde> 6 hydrogen 6 oxygen (12 elements)
Hydrogen peroxyde is 50% hydrogen
Distilled water is 66.6% hydrogen
Wich has the highest percentage of hydrogen?
Come on!?

Answer 4

Yep its water

water 2 amu /18 amu times 100 = 11 %

Hydrogen Peroxide 2 amu / 34 amu times 100 = 5.9 %

shortstuff (see above) has a more complete explanation.

Answer 5

water
oxygen has a greater mass than hydrogen... h2o2 has more oxygen and therefore less hydrogen by mass than water does (as a percentage)