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Solving Problems: A Chemistry Handbook
Chemistry: Matter and Change
101
SOLVING PROBLEMS:
A CHEMISTRY HANDBOOK
CHAPTER 10
Next, calculate the molar mass represented by the formula CHO.
Here, the molar mass is the sum of the masses of one mole of each
element.
molar mass CHO ϭ 12.011 g ϩ 1.008 g ϩ 15.999 g
molar mass CHO ϭ 29.018 g/mol
As stated in the problem, the molar mass of maleic acid is known to
be 116.1 g/mol. To determine the molecular formula for maleic
acid, calculate the whole number multiple, n, to apply to its empirical formula.
n ϭ
ϭ 4.001
This calculation shows that the molar mass of maleic acid is four
times the molar mass of its empirical formula CHO. Therefore, the
molecular formula must have four times as many atoms of each element as the empirical formula. Thus, the molecular formula is
(CHO)4 ϭ C 4 H 4 O 4 . A check of the molecular formula for maleic
acid in a reference book will confirm this result.
Practice Problems
30. Ricinine is one of the poisonous compounds found in the castor
plant. The composition of ricinine is 58.54% carbon, 4.91%
hydrogen, 17.06% nitrogen, and 19.49% oxygen. Ricinine’s
molar mass is 164.16 g/mol. Determine its molecular formula.
31. The compound borazine consists of 40.29% boron, 7.51%
hydrogen, and 52.20% nitrogen, and its molar mass is
80.50 g/mol. Calculate the molecular formula for borazine.
32. The composition of silver oxalate is 71.02% silver, 7.91% carbon, and 21.07% oxygen. If the molar mass of silver oxalate is
303.8 g/mol, what is its molecular formula?
33. A compound of phosphorus and sulfur contains 27.87% phosphorus and 72.13% sulfur. The molar mass of the compound is
222.3 g/mol. Calculate its molecular formula.
34. Triethylenemelamine is used in the plastics industry and as an
anticancer drug. Its analysis is 52.93% carbon, 5.92% hydrogen,
and 41.15% nitrogen. The molar mass of triethylenemelamine is
204.2 g/mol. Determine its molecular formula.
116.1 g/mol maleic acid
ᎏᎏᎏ
29.018 g/mol CHO
Solving Problems: A Chemistry Handbook
Chemistry: Matter and Change
101
SOLVING PROBLEMS:
A CHEMISTRY HANDBOOK
CHAPTER 10
Next, calculate the molar mass represented by the formula CHO.
Here, the molar mass is the sum of the masses of one mole of each
element.
molar mass CHO ϭ 12.011 g ϩ 1.008 g ϩ 15.999 g
molar mass CHO ϭ 29.018 g/mol
As stated in the problem, the molar mass of maleic acid is known to
be 116.1 g/mol. To determine the molecular formula for maleic
acid, calculate the whole number multiple, n, to apply to its empirical formula.
n ϭ
ϭ 4.001
This calculation shows that the molar mass of maleic acid is four
times the molar mass of its empirical formula CHO. Therefore, the
molecular formula must have four times as many atoms of each element as the empirical formula. Thus, the molecular formula is
(CHO)4 ϭ C 4 H 4 O 4 . A check of the molecular formula for maleic
acid in a reference book will confirm this result.
Practice Problems
30. Ricinine is one of the poisonous compounds found in the castor
plant. The composition of ricinine is 58.54% carbon, 4.91%
hydrogen, 17.06% nitrogen, and 19.49% oxygen. Ricinine’s
molar mass is 164.16 g/mol. Determine its molecular formula.
31. The compound borazine consists of 40.29% boron, 7.51%
hydrogen, and 52.20% nitrogen, and its molar mass is
80.50 g/mol. Calculate the molecular formula for borazine.
32. The composition of silver oxalate is 71.02% silver, 7.91% carbon, and 21.07% oxygen. If the molar mass of silver oxalate is
303.8 g/mol, what is its molecular formula?
33. A compound of phosphorus and sulfur contains 27.87% phosphorus and 72.13% sulfur. The molar mass of the compound is
222.3 g/mol. Calculate its molecular formula.
34. Triethylenemelamine is used in the plastics industry and as an
anticancer drug. Its analysis is 52.93% carbon, 5.92% hydrogen,
and 41.15% nitrogen. The molar mass of triethylenemelamine is
204.2 g/mol. Determine its molecular formula.
116.1 g/mol maleic acid
ᎏᎏᎏ
29.018 g/mol CHO