Unit 8—The Mole
Name
Pre-AP Chemistry
Period
Date
Lab: Using Molar Mass to Identify a Substance
Purpose
The purpose of this activity is to experimentally determine the molar mass of an unknown substance
and to determine the identity of the substance based upon its molar mass. Your unknown substance
is one of the following: NaHCO3 , MgSO4 ● 7H2O , NaCl, or C12H22O11.
Pre-Lab Calculations
Determine the molar mass of each of the following substances. Show your work!
a.
NaHCO3
b.
MgSO4 ● 7H2O
(add the mass of MgSO4 to the mass of 7 H2O’s. Don’t multiply!)
c.
NaCl
d.
C12H22O11
Materials
Container of Unknown Substance
Periodic Table
Electronic Balance
Calculator
Procedure
Unknown # (given on label)
Mass of container and unknown substance
Mass of container (given on label)
Number of moles of the unknown substance (given on label)
Questions and Calculations (show your work)
1.
Calculate the mass of the unknown substance.
2.
Calculate the molar mass of the unknown substance.
3.
What is the identity of your unknown substance?