Determine the amu of each element in the compound (periodic table).
Multiply the amu by the element's subscript in the formula to determine the mass of the element in that compound.
Determine the molar mass of the compound (sum the masses of each element).
Divide each element's mass by the compound's molar mass, then multiply by 100.
Rounding - generally, round the percent composition to the nearest hundredth.
Directions - determine the percent composition of each element in the following compounds. Do not forget to include the correct unit for each calculation (grams, percent).
Question 1
1.
SiO2
Molar Mass of compound = _______
Percent Compositions:
Si = _______
O = _______
Do not forget to include the correct unit for each calculation
Question 2
2.
(NH4)2S
Molar Mass of Compound = _______
Percent Compositions:
N = _______
H = _______
S = _______
Do not forget to include the correct unit for each calculation
Question 3
3.
NO2
Molar Mass of Compound = _______
Percent Compositions:
N = _______
O =_______
Do not forget to include the correct unit for each calculation
Question 4
4.
KCN
Molar Mass of Compound = _______
Percent Compositions:
K = _______
C = _______
N = _______
Do not forget to include the correct unit for each calculation
Question 5
5.
PI3
Molar Mass of Compound =_______
Percent Compositions:
P =_______
I =_______
Do not forget to include the correct unit for each calculation
To determine percent composition:
Determine the amu of each element in the compound (periodic table).
Multiply the amu by the element's subscript in the formula to determine the mass of the element in that compound.
Determine the molar mass of the compound (sum the masses of each element).
Divide each element's mass by the compound's molar mass, then multiply by 100.
Rounding - generally, round the percent composition to the nearest hundredth.
Directions - determine the percent composition of each element in the following compounds. Do not forget to include the correct unit for each calculation (grams, percent).
Question 6
6.
NH4Cl
Molar Mass of Compound = _______
Percent Compositions:
N = _______
H = _______
Cl = _______
Do not forget to include the correct unit for each calculation
Question 7
7.
KMnO4
Molar Mass of Compound = _______
Percent Compositions:
K = _______
Mn = _______
O = _______
Do not forget to include the correct unit for each calculation
Question 8
8.
NH4CO3
Molar Mass of Compound = _______
Percent Compositions:
N = _______
H = _______
C = _______
O = _______
Do not forget to include the correct unit for each calculation
Question 9
9.
C8H10N4O2
Molar Mass of Compound = _______
Percent Compositions:
C = _______
H = _______
N = _______
O = _______
Do not forget to include the correct unit for each calculation
Question 10
10.
Cu3(CO3)2(OH)2
Molar Mass of Compound = _______
Percent Composition:
Cu = _______
C = _______
O = _______
H = _______
Do not forget to include the correct unit for each calculation