Name

Period

Date

Empirical Formula of CuO Lab

OBJECTIVE

• Burn copper to produce copper (II) oxide, CuO, then determine its empirical formula.

INFO

• Empirical formulas show the ratio of elements in a compound.
• Cu molar mass = 63.546 g/mol
• O molar mass = 15.999 g/mol

MATERIALS

• bunsen burner
• ring stand, ring, clay triangle
• crucible
• tongs, leather gloves
• copper metal

DATA

1. mass of crucible = g
2. mass of crucible and copper = g
3. mass of crucible and copper (II) oxide = g

PROCEDURE

1. zero balance
2. mass out crucible
3. place Cu into crucible and mass out
4. heat crucible until all Cu has reacted with oxygen in air
5. use tongs to move crucible (hot!)
6. mass out crucible and copper compound

CALCULATIONS

1. mass of copper = b - a =
2. moles of copper = (see board) =
3. mass of copper (II) oxide = c - a =
4. mass of oxygen = #3 - #1 =
5. moles of oxygen = (see board) =
6. mole ratio = #2 / #5 =
7. percent error = (see board) =

CONCLUSION

• predicted empirical formula for copper (II) oxide
• calculate moles to 5 decimal places
• divide the moles of Cu into the moles of O, and use this as your experimental value (WYG)
• use the value of one, 1, as your expected value (WYSHG)
• calculate the percent error