Solve Mass Fraction Problem: 100g H2O, 11.2g H, 3.06g H2

[lucky_star]

Homework Statement

If 100 g H2O contains 11.2 g H, what mass of water could be obtained from 3.06 g H2(g) reacting with an excess of O2(g)?

Homework Equations

Mass % of X in a sample= (Mass of X in sample/ Mass of the sample)*100

The Attempt at a Solution

The parts that confused me were 11.2g of H and the 3.06g H2. Why aren't both be H2 or H? Can anyone help me with this problem? THank you in advance.

This is my effort:
I look for the mass fraction of H in 100g of H2O:
11.2g of H/100g H2O= .112

Then, I find the Mass of H2O
3.06g/.112 = 27.3g H2O

Is this correct?

 

[Borek]

The parts that confused me were 11.2g of H and the 3.06g H2. Why aren't both be H2 or H?

Is mass of 3.5 g of H different from the mass of 3.5 g H₂? Do they differ in number of atoms of hydrogen?

This is my effort:
I look for the mass fraction of H in 100g of H2O:
11.2g of H/100g H2O= .112

Then, I find the Mass of H2O
3.06g/.112 = 27.3g H2O

Is this correct?

Yes.

 

[lucky_star]

Is mass of 3.5 g of H different from the mass of 3.5 g H2? Do they differ in number of atoms of hydrogen?

No, they are not the same. I understand it now.

Thank you Borek!

 

[Borek]

No, they are not the same. I understand it now.

Oops, not good. They ARE the same and they DON'T differ in terms of the number of hydrogen atoms.

 

[lucky_star]

Oh, Thanks again :)