Name: ______________________ Period: ______________________ Date: _______________________ Review Packet: Math of Chemistry Counting Atoms and Gram Formula Mass Directions: count the atoms in each compound. Then solve for the gram formula mass 1. Na2CO3 5. NH4C2H3O2 2. Ca3(PO4)2 6. Al2(CO3)3 3. K2CrO4 7. Pb(NO3)2 4. BaCl2 8. (NH4)2Cr2O7 Unit 1: Math of Chemistry 1 Name: ______________________ Period: ______________________ Date: _______________________ Determining Percent Composition Directions: Determine the percent composition of the given element in the given compounds 9. % composition of O in CO2 10. % composition of C in CH20 11. % composition of S in H2SO4 12. % composition of Cu in CuSO4 13. % composition of Cl in CHCl3 14. % composition of H in C12H22O11 15. % composition of N in C14H20N2SO4 Unit 1: Math of Chemistry 2 Name: ______________________ Period: ______________________ Date: _______________________ Calculating Moles Directions: Calculate the number of moles or grams in each element 16. How many moles are in 15 grams of lithium? 17. How many grams are in 2.4 moles of sulfur? 18. How many moles are in 22 grams of argon? 19. How many grams are in 88.1 moles of magnesium? 20. How many moles are in 2.3 grams of phosphorus? 21. How many grams are in 11.9 moles of chromium? 22. How many moles are in 9.8 grams of Calcium? 23. How many grams are in 238 moles of arsenic? Directions: Calculate the molecular weights of the following compounds. 24. NaOH 27. H3PO4 25. H2O 28. Mn2Se7 26. MgCl2 29. (NH4)SO4 Unit 1: Math of Chemistry 3 Name: ______________________ Period: ______________________ Date: _______________________ Finding Empirical and Molecular Formulas Directions: Find the molecular or empirical formulas 30. Find the molecular formula for the compound with an empirical formula of C2H3 and a molar Mass of 189.0 g/mol. Show all work. 31. A compound has an empirical formula of CH2 and a molecular mass of 28 amu. What is the molecular formula? Show all work. 32. Vitamin C has an empirical formula of C3H4O3 and a molecular mass of 176 amu. What is its molecular formula? Show all work. 33. A compound has a molar mass of 90 grams per mole and the empirical formula CH2O. What is the molecular formula of this compound? a. C2H4O2 c. C3H6O3 b. C4H8O4 d. CH2O 34. A substance has an empirical formula of CH2 and a molar mass of 56 grams per mole. The molecular formula for this compound is: a. C8H4 c. C4H8 b. CH2 d. C4H6 35. A compound has an empirical formula of HCO2 and a molecular mass of 90 grams per mole. What is the molecular formula of this compound? a. H6C6O12 c. HCO b. H2C2O4 d. C4C4O8 36. What is the molecular formula of a compound that has a molecular mass of 92 and an empirical formula of NO2? a. N3O6 b. N2O4 Unit 1: Math of Chemistry c. NO2 d. N4O8 4 Name: ______________________ Period: ______________________ Date: _______________________ Balancing Equations and Mole Ratios Directions: Use the balanced chemical equations to answer the following questions. 37. 6HCl + Fe2O3 → 2 FeCl3 + 3 H2O a. If 3 moles of HCl react in the above reaction, how many moles of FeCl3 would be produced? b. If 6 moles of H2O were produced, how many moles of FeCl3 would be produced? 38. 2Al + 3S → Al2S3 a. If 10 moles of Al react, how many moles of S would be needed? b. If 1.0 moles of S are reacted, how much Al2S3 is produced? 39. 2C2H2 + 5O2 → 4CO2 + 2H20 a. How many moles of CO2 are produced when 5.0 moles of C2H2 are reacted? b. If 16 moles of Co2 are produced in the reaction, how many moles of O2 reacted? 40. H2 + Cl2 → 2NH3 a. How many moles of hydrogen are needed to completely react with 2.5 moles of nitrogen? Directions: Balance the following equations. 41. _____ NaBr + _____ H3PO4 → _____Na3PO4 + _____HBr 42. _____ Ca(OH)2 + _____Al2(SO4)3 → _____CaSO4 + _____ Al(OH)3 43. _____ Mg + _____Fe2O3 → _____Fe + _____MgO 44. _____ C2H4 + _____ O2 → _____ CO2 + _____H2O 45. _____PbSO4 → _____PbSO3 + _____O2 46. _____ NH3 + ______I2 → _____N2I6 + _____ H2 47. _____ H2O + _____ SO3 → _____H2SO4 48. _____ H2SO4 + _____ NH4OH → _____ H2O + _____ (NH4)2SO4 Unit 1: Math of Chemistry 5
