Lab 9: Empirical Formulas & Molecular Formulas
Date:
Name/Partner
Purpose: To determine the empirical and molecular formulas of various unknown
compounds.
Procedure:
1. Determine the number of atoms in a pure sample of one of the elements in
the NEW PERIODIC TABLE.
A. Determine the mass of your pure element.
B. Use the table below to determine the Molar Mass of your known element.
C. Calculate the number of atoms within your known elemental sample.
2. Determine the number of molecules of a known compound formed by the
elements in the NEW PERIODIC TABLE.
A. Determine the mass of your pure compound.
B. Use the table below to determine the Molar Mass of your known compound.
C. Calculate the number of molecules within your known compound.
3. Determine the Empirical Formula and of an unknown compound from its original
mass and the mass of its individual elements.
A. Determine the mass of the pure compound.
B. Determine the masses of the individual elements that were found to be within
your pure compound.
C. Determine the Empirical Formula of your sample.
Washers - 1A
Gw -Goldwash
1.32
Nuts - 2A
Bolts - 3A
Jw - Jordanwash
3.90
Dn - Dosenut
5.07
Ab - Autumnbolt
5.07
Sw - Splitwash
6.54
Rn - Rebanut
6.90
Kb - Katibolt
8.34
Bolts - 4A
Bolts - 5A
Bolts - 6A
Jb - Jbolt
12.6
Wb - Wallbolt
21.2
Dw
Downeywash
25.9
Mn - Marcoconut
28.6
An - Allinut
40.9
Tw - Tywash
52.0
Cb - Connobolt
77.0
1 Molly = 6 particles (atoms, molecules, ions, formula units)
Hb - Huenebolt
149.
Lab 9: follow-up
Conclusions & Questions:
1. Determine the empirical formula from a compound composed of Dw and Cb (NOT Cn). After
decomposing this compound, the masses of the parts are found to be 25.0 g of Dw and
147.80 g of Cb.
2. Determine the empirical formula from a compound composed of Dn, Rn, Gw, and Wb. Again,
after decomposition of this compound the masses were found to be 7.5g, 15.3g, 1.95g, and
15.9 g respectively.
3. Determine the empirical formula of another compound whose constituent parts have the following
masses: Mn = 110.0 g ; Ab = 27.5 g. Try to determine the empirical formula by dividing the
larger mass by the smaller mass and the smaller mass by itself. Why are these values
WRONG?
Lab 9: follow-up
Conclusions & Questions:
1. Determine the empirical formula from a compound composed of Dw and Cb (NOT Cn). After
decomposing this compound, the masses of the parts are found to be 25.0 g of Dw and
147.80 g of Cb.
2. Determine the empirical formula from a compound composed of Dn, Rn, Gw, and Wb. Again,
after decomposition of this compound the masses were found to be 7.5g, 15.3g, 1.95g, and
15.9 g respectively.
3. Determine the empirical formula of another compound whose constituent parts have the following
masses: Mn = 110.0 g ; Ab = 27.5 g. Try to determine the empirical formula by dividing the
larger mass by the smaller mass and the smaller mass by itself. Why are these values
WRONG?
Lab 9: follow-up
Conclusions & Questions:
1. Determine the empirical formula from a compound composed of Dw and Cb (NOT Cn). After
decomposing this compound, the masses of the parts are found to be 25.0 g of Dw and
147.80 g of Cb.
2. Determine the empirical formula from a compound composed of Dn, Rn, Gw, and Wb. Again,
after decomposition of this compound the masses were found to be 7.5g, 15.3g, 1.95g, and
15.9 g respectively.
3. Determine the empirical formula of another compound whose constituent parts have the following
masses: Mn = 110.0 g ; Ab = 27.5 g. Try to determine the empirical formula by dividing the
larger mass by the smaller mass and the smaller mass by itself. Why are these values
WRONG?
Lab 9: follow-up
Conclusions & Questions:
1. Determine the empirical formula from a compound composed of Dw and Cb (NOT Cn). After
decomposing this compound, the masses of the parts are found to be 25.0 g of Dw and
147.80 g of Cb.
2. Determine the empirical formula from a compound composed of Dn, Rn, Gw, and Wb. Again,
after decomposition of this compound the masses were found to be 7.5g, 15.3g, 1.95g, and
15.9 g respectively.
3. Determine the empirical formula of another compound whose constituent parts have the following
masses: Mn = 110.0 g ; Ab = 27.5 g. Try to determine the empirical formula by dividing the
larger mass by the smaller mass and the smaller mass by itself. Why are these values
WRONG?