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Topic 6: Mole and stoichiometry - Mathematics of formulas and equations
6. Percent composition: Calculation of percent composition from formulas
1. The percent composition by mass of Fluorine in F2 is 3) 19 % 4) 8 %
1) 50 %
2) 100 %
2. The approximate percent composition of oxygen in SO3 is 3) 60 % 4) 80 %
1) 20 %
2) 40 %
3. What is the percent composition of nitrogen in the compound NH4NO3?
1) 35 % 2) 29 % 3) 18 % 4) 5.7 %
4. In the formula Mg(CN)2, what is the approximate percent by mass of carbon?
1) 16 % 2) 32 % 3) 24% 4) 48 %
Teacher Preview Copy
5. What is the approximate percent by mass of hydrogen in the formula C3H5(OH)3 ?
1) 6.5 % 2) 4.8 % 3) 8.7 % 4) 3.6 %
6. What is the percent by mass of phosphorous in the compound Ca3(PO4)2?
1) 20 % 2) 10 % 3) 80 % 4) 14 %
7. Which set up correct for calculating the percent by mass of carbon in the compound HC2H3O2?
x 100 x 100 x 100 x 100
1) 12 2) 60 3) 24 4) 60
60 12
60
24
8. The percent by mass of magnesium in the formula Mg(ClO3)2 is equal to
2) 190
3 ) 48
x 100
x 100
x 100
1) 190 Teacher Preview Copy 4) 24 x 100
24 48 190 190
9. What is the approximate percent composition by mass of CaBr2 (formula mass = 200 g/mole) ?
1) 20 % calcium and 80 % bromine 3) 30 % calcium and 70 % bromine
2) 25 % calcium and 75 % bromine 4) 35 % calcium and 65 % bromine
10. What is the approximate percent composition of CaCO3? 3) 40 % Ca , 12 % C and 48 % O
1) 48 % Ca, 12 % C and 40 % O
2) 12 % Ca, 48 % C, and 40 % O 4) 40 % Ca , 48 % C, and 12 % O
11. Which formula contains the greatest percent by mass of oxygen?
1) NO 2) NO2 3) N2O 4) N2O2
12. Which formula has the least percent composition by mass of carbon?
1) CH4 2) C2H2 3) C2H6 4) C3H8
13. Which compound has the greatest composition of sulfur by mass?
1) Fe2(SO4)3 2) FeSO4 3) Fe2(SO3)3 4) FeSO3
14. In which compound does manganese has the least percent composition by mass?
1) Manganese (II) oxide 3) Manganese (II) chloride
2) Manganese (III) oxide 4) Manganese (III) chloride
15. Which compound of gold will produce the greatest mass of gold?
1) Gold (I) oxide 3) Gold (I) sulfide
2) Gold (III) oxide 4) Gold (III) sulfide
226 Copyright © 2010 E3 Scholastic Publishing. All Rights Reserved. Survivingchem.com
Topic 6: Mole and stoichiometry - Mathematics of formulas and equations
6. Percent composition: Calculation of percent composition from formulas
1. The percent composition by mass of Fluorine in F2 is 3) 19 % 4) 8 %
1) 50 %
2) 100 %
2. The approximate percent composition of oxygen in SO3 is 3) 60 % 4) 80 %
1) 20 %
2) 40 %
3. What is the percent composition of nitrogen in the compound NH4NO3?
1) 35 % 2) 29 % 3) 18 % 4) 5.7 %
4. In the formula Mg(CN)2, what is the approximate percent by mass of carbon?
1) 16 % 2) 32 % 3) 24% 4) 48 %
Teacher Preview Copy
5. What is the approximate percent by mass of hydrogen in the formula C3H5(OH)3 ?
1) 6.5 % 2) 4.8 % 3) 8.7 % 4) 3.6 %
6. What is the percent by mass of phosphorous in the compound Ca3(PO4)2?
1) 20 % 2) 10 % 3) 80 % 4) 14 %
7. Which set up correct for calculating the percent by mass of carbon in the compound HC2H3O2?
x 100 x 100 x 100 x 100
1) 12 2) 60 3) 24 4) 60
60 12
60
24
8. The percent by mass of magnesium in the formula Mg(ClO3)2 is equal to
2) 190
3 ) 48
x 100
x 100
x 100
1) 190 Teacher Preview Copy 4) 24 x 100
24 48 190 190
9. What is the approximate percent composition by mass of CaBr2 (formula mass = 200 g/mole) ?
1) 20 % calcium and 80 % bromine 3) 30 % calcium and 70 % bromine
2) 25 % calcium and 75 % bromine 4) 35 % calcium and 65 % bromine
10. What is the approximate percent composition of CaCO3? 3) 40 % Ca , 12 % C and 48 % O
1) 48 % Ca, 12 % C and 40 % O
2) 12 % Ca, 48 % C, and 40 % O 4) 40 % Ca , 48 % C, and 12 % O
11. Which formula contains the greatest percent by mass of oxygen?
1) NO 2) NO2 3) N2O 4) N2O2
12. Which formula has the least percent composition by mass of carbon?
1) CH4 2) C2H2 3) C2H6 4) C3H8
13. Which compound has the greatest composition of sulfur by mass?
1) Fe2(SO4)3 2) FeSO4 3) Fe2(SO3)3 4) FeSO3
14. In which compound does manganese has the least percent composition by mass?
1) Manganese (II) oxide 3) Manganese (II) chloride
2) Manganese (III) oxide 4) Manganese (III) chloride
15. Which compound of gold will produce the greatest mass of gold?
1) Gold (I) oxide 3) Gold (I) sulfide
2) Gold (III) oxide 4) Gold (III) sulfide
226 Copyright © 2010 E3 Scholastic Publishing. All Rights Reserved. Survivingchem.com
