A 4.08 g sample of a compound of nitrogen and oxygen contains 3.02 g of oxygen. What is the empirical formula?

1 Answer
Jul 28, 2016

Answer:

The empirical formula is #"N"_4"O"#.

Explanation:

An empirical formula is the lowest whole number ratio of elements in a compound. Each ratio will be the subscript of each element.

Determine the mass of each element in grams.

#"N":# #"4.08 g"-"3.02g"="1.06 g"#

#"O":# #"3.02 g"# (given)

Determine moles of each element by dividing the mass of each element by its molar mass (atomic weight on the periodic table in g/mol.

#"N":# #"1.06 g N"/"14.007 g/mol"="0.0756764 mol N"#

#"O":# #"3.02 g O"/"15.999 g/mol"="0.188761 mol O"#

Determine mole ratios by dividing the moles of each element by the least number of moles.

#"N":# #"0.0756764 mol"/"0.188761 mol"="4.01"~~4#

#"O":# #"0.188761 mol"/"0.188761"=1.00=1#

The empirical formula is #"N"_4"O"#.

The compound with this formula is called nitrosylazide with the following structure.

https://en.m.wikipedia.org/wiki/Nitrosylazide

For more examples of this type of empirical formula problem, check out the following website: http://www.chemteam.info/Mole/Emp-formula-given-mass-data.html

For examples of determining an empirical formula from percent composition, check out this website: https://www.chem.tamu.edu/class/majors/tutorialnotefiles/empirical.htm