Name___________________________________________________________Per_____Date____________________
Lab Partners__________________________________________________________________Station#_____________
EMPIRICAL FORMULA OF ZINC CHLORIDE
The empirical formula is the ratio formula. It is the ratio of atoms in a compound. The molecular formula is
the actual number of atoms in a molecular unit. The molecular formula may be the same as the empirical formula or
it may be some integer multiple of the empirical formula. The empirical formula is relatively easy to determine. If
the mass of each atom is the compound is known, mass can be expressed in terms of number of moles. The mole
ratio can be expressed in terms of an integer ratio which is the ratio of atoms. The ratio of atoms can be used as
subscripts in the empirical formula.
PROCEDURE:
1. Weigh a clean, dry 100 mL beaker and record as tare weight. Label the beaker with your period and lab
station number.
2. Your instructor will instruct you as to the mass of zinc to be used and will distribute the zinc to you. Weigh
the zinc to determine that you have the correct mass of zinc and record the mass of zinc that you used.
Calculate the moles of zinc.
3. Use your 50 mL beaker to measure about 20 mL of 3 M hydrochloric acid (3 M HCl). (WEAR SAFTEY
GOGGLES!!) Carefully pour the hydrochloric acid into the 100 mL beaker with the zinc. The acid will react
with the zinc producing hydrogen gas and zinc chloride. The zinc chloride is water soluble and will remain in
solution until the water is removed. Give the beaker to your instructor to dry overnight in the fume hood.
4. After the zinc chloride is dried, weigh the zinc chloride in the beaker and record. Calculate the mass of zinc
chloride present and the mass of chloride (chloride is the name of combined chlorine). Calculate the moles of
chlorine present.
5. Calculate the ratio of moles of chlorine to moles of zinc. Round off the mole ratio to determine the ratio of
atoms of chlorine to atoms of zinc. Use the ratio of atoms as subscripts to write the empirical formula.
Name___________________________________________________________Per_____Date____________________
Lab Partners__________________________________________________________________Station#_____________
EMPIRICAL FORMULA OF ZINC CHLORIDE LAB
*SHOW ALL WORK/CALCULATION SET UPS IN SPACE PROVIDED*
1. Tare weight of 100 mL beaker
2. Mass of 100 mL beaker with zinc metal
3. Mass of zinc metal*
4. Moles of zinc metal*
5. Number of atoms of zinc metal*
6. Mass of 100 mL beaker with DRY zinc chloride
7. Mass of dry zinc chloride*
8. Mass of chlorine present in the dry zinc chloride*
9. Moles of chlorine present in the dry zinc chloride*
10. Number of atoms of chlorine present in the dry zinc chloride*
11. Ratio of moles of zinc to moles of chlorine*
12. Ratio of atoms of zinc to atoms of chlorine*
13. Empirical formula of zinc chloride
DETERMINE WHICH OF THE FOLLOWING ARE EMPIRICAL FORMULAS (EF) OR MOLECULAR FORMULAS (MF)
14. H2S2O8
17. C6H12O6
20. C10H8
15. C4H10O
18. C2H4
21. Fe2O3
16. C9H8O4
19. TiO2
22. C4H8O2
23. Write the empirical formulas for the items you labeled as molecular formulas