A compound is composed of element x and hydrogen. Analysis shows the compound to be 80% x by mass, with three times as many hydrogen atoms as x atoms per molecule.
which element is element x
the answer is carbon but why????
please explain
2007-08-13 08:07:58 · 3 answers · asked by jazzchick 2 in Science & Mathematics ➔ Chemistry
The empirical formula of the compound is XH3, with three times as many hydrogen atoms as X atoms per molecule. In order to be 80% X by mass, we must have the mass of an X atom equal to four times the mass of 3 H atoms, so the atomic mass of X must be equal to 12 times the atomic mass of hydrogen. H has atomic mass of 1, 12 times 1 is 12, and carbon has atomic mass of 12. You can see that CH3 has an atomic mass of 12 + 3*1 = 15, and carbon accounts for 12/15 = 0.8 = 80% of that mass.
2007-08-13 08:17:10 · answer #1 · answered by DavidK93 7 · 0⤊ 0⤋
One mole of XH3 contains 3g of hydrogen. (20%) and 12 g of X (80% is 4 times bigger)
Result: one mole of XH3 contians 12 g of X. 12 is the atomic mass of carbon.
2007-08-13 15:21:10 · answer #2 · answered by Sciman 6 · 0⤊ 0⤋
n=no of atoms of x
3n = no of atoms of H
n(at.mass of x) = total mass of x
3n(at.mass of H) = total mass of H
since 80% of mass is x that means there is 4 times more mass from x than H. ie. 80/20=4
4(3n(1))=n(at.mass of x) divide out the n
12=at. mass of x. That would be carbon.
2007-08-13 15:24:57 · answer #3 · answered by chasrmck 6 · 0⤊ 0⤋