Hi teatea!!
A gram atomic mass of an element is that quantity of an element whose
mass in grams is numerically equal to its atomic mass. For example,
the atomic mass of carbon is 12.01115. Therefore, 12.01115 grams of
carbon is one gram atomic mass of carbon.
A gram atomic mass of ANY element contains the same number of atoms.
This number, 6.02x1023, is called Avogadro’s number N.
The molecular (formula) mass of a compound is the sum of the atomic
masses of all the atoms in one molecule (or one formula unit) of the
compound. A gram molecular (formula) mass of a compound is that
quantity of a compound whose mass in grams equals its molecular
(formula) mass. As in the case of gram atomic mass, a gram molecular
mass of a compound is equal to one mole.
-Empirical formulas:
An empirical formula represents the simplest ratio in which atoms
combine to form a compound.
Taken from "Chemical Equations" a PowerPoint presentation from "The
Catalyst!" website, follow this link to download this useful document:
http://www.thecatalyst.org/download/cfilkins/ChemicalEquations.ppt
Solution to the problem:
Recall that 1 gram-atom of carbon has a mass of approximately 12.0g,
while 1 gram-atom of hydrogen is about 1.0g and for the nitrogen is
14.0g.
For simplicity we can say that the compound consists of 48 grams of
carbon, 12 grams of hydrogen, and 28 grams of nitrogen (multyplying by
ten all the values). Dividing by 12g (the gram-atom of the carbon) the
quantity of crabon in the compound we find that the compound has 4
gram-atoms of carbon. Doing the same for the other elements in the
compound we obtain the following results:
4 gram-atom of Carbon;
12 grams-atom of hydrogen;
2 grams-atom of nitrogen.
Simplifying we have:
2 gram-atom of Carbon;
6 grams-atom of hydrogen;
1 grams-atom of nitrogen
So the empirical formula of our compound is:
c. C2H6N
Hope this helps. Ask for a clarification if it is needed.
Regards.
livioflores-ga |
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