What is the mass percent of hydrogen for #C_3H_5OH#?

1 Answer
Jan 2, 2017

Answer:

#color(red)(10.41%)#

Explanation:

In order to compute the mass percent of hydrogen in #C_3H_5OH# we're going to need two things:

#color(brown) "1: The formula mass of the entire compound"#
#color(brown) "2: The atomic mass of hydrogen"#

The formula mass of #C_3H_5OH# is #58.08 g/(mol)# because:

#3(12.01g/(mol)) + 6(1.008g/"mol") + (16.00 g/"mol")# #= 58.08 g/(mol)#

The atomic mass of the hydrogen atom is #1.008 g/(mol)#

Now, we have to use the following equation:

http://www.chemieleerkracht.be/index.php/2-uncategorised/609-eee-375

The numerator represents the mass of the desired atom, which is H in our case, and the denominator represents the mass of the entire compound. You just divide the two and multiply by 100 to obtain the percent composition:

#"Mass of H"/("Molar Mass of C"_3"H"_5"OH") xx100%#

#"(6)1.008 g/mol"/"58.08g/mol"xx100% = 10.41%#

I multiplied the atomic mass of hydrogen by 6 because you have to account for all of the hydrogen atoms in the formula.