Name _________________________________________ Date
______________ Period ______________
Chemistry Lab Mole:
Measuring Mass as a Means of Counting
Purpose: Determine the number of atoms that fit on one tea spoon.
1. Use one clean and dry 50 mL beaker. Place on a balance and press the zero button until the
display shows 0.00.
2. Place one level teaspoon of sodium chloride (NaCl) into the beaker, determine the mass and
record in the table (row 1).
3. Repeat steps 1-2 for CaCO3
4. Repeat steps 1-2 for H2O
5. Use a clean and dry evaporating dish instead of a beaker to repeat steps 1-2 for ethanol C2H6O
6. Complete the data table by performing the following calculations on a separate sheet:
Row 2: Determine the molar mass of each compound (check the periodic table…)
Row 3: Determine the amount of mol you scooped for each sample
grams (row 1) x
1 mol
= mol of compound
Molar mass (row 2)
Row 4: Determine the number of particles (molecules or formula units) for each compound
# of moles (row 3) x
6.02 x 1023 particles = # of particles
1 mol
Row 5: Determine the number of atoms in each formula (add all subscripts in the formula).
Row 6 Determine the number of atoms in each sample you scooped
(row 4) x (row 5) = # of atoms in the sample
Data Table
Row
#
1
Compound
NaCl
CaCO3
H2O
2
5
3
C2H6O
Mass of compound (grams)
Molar mass (g/mol)
(Periodic Table …)
3
Moles of compound in your
beaker (mol)
4
# of representative particles
(molecules or formula units)
in each compound
5
# of atoms in each formula
6
# of atoms in each sample
(multiply row 4 x row 5)
Analysis
7. Which of the three compound samples had the highest mass (row 1)?
8. Which of the three compound samples contains the greatest number of atoms (row 6)?
9. Are your answers for 7 and 8 the same or different? How do you explain the difference?