Name: ______________________________________
Date: ____________ Period: ____
Lab – How Many Moles & Particles are in that Mass?
Purpose:
The purpose of this lab is for you to measure the mass of several common items used in
everyday life, and to then convert these masses into moles and numbers of particles.
Remember, there are 6.02 x 1023 particles in a mole.
Procedure A: How many water molecules in a mouthful of water?
Fill a paper cup with water. Wipe off the outside. Determine the mass and record it. Drink one
mouthful of water. Reweigh the cup and water and record the mass. Throw away the cup!
Data:
Mass of cup & water before drinking: _______________ g
Mass of cup & water after drinking: _______________ g
Calculations: Show all work. The molar mass of H2O is ________ g/mol. (Add from Periodic Table)
Mass of water swallowed:
g
Moles of water swallowed:
_________g x __1_mol =
18.02 g
.
mol
Number of molecules of water swallowed:
_________mol x 6.02 x 1023 molecules =
1 mol
.
molecules
1
Procedure B: How many formula units are in a teaspoon of salt?
Weigh a plastic weighing boat and record its mass. Add a teaspoon of salt, reweigh and record
the mass. Return the salt to its container.
Data:
Mass of weighing boat:
_____________ g
Mass of weighing boat + salt
_____________ g
Calculations: Show all work. The molar mass of NaCl is _________ g/mol. (Add from Periodic Table)
Mass of salt:
g
Moles of salt in a teaspoon:
_________g x _____mol =
_______g
mol
.
Number of formula units of NaCl in a teaspoon of salt:
_________mol x 6.02 x 1023 units =
_____mol
units
.
Procedure C: How many copper atoms are in a copper penny?
Weigh a pre-1983 penny and record its mass.
Data:
Mass of penny:
____________ g
Calculations: Show all work. The molar mass of Cu is ________ g/mol. (from Periodic Table)
Mass of penny:
g
Moles of copper in a penny:
_____________ x ____________ =
mol
Number of copper atoms in a copper penny:
_____________ x _________________ =
.
atoms
2
Post Lab Questions & Calculations:
1: How many grams of carbon in a sample of 2.11 x 1024 atoms of C?
Calculations: Show all work. The molar mass of C is _________ g/mol. (from Periodic Table)
Atoms of carbon:
2.11 x 1024 atoms
Moles of carbon:
_____________atoms x _______mol
6.02 x 1023 atoms
.
=
mol
Mass of carbon:
_________mol x _________g =
_______mol
g
.
2: How many grams of sugar are in a sugar cube with 4.04 x 1021 molecules of sugar?
Calculations: Show all work. The molar mass of sugar (C12H22O11) is 342.34 g/mol.
Molecules of sugar in a sugar cube:
molecules
Moles of sugar in a sugar cube:
_____________molecules x _____
mol
=
____________molecules
.
mol
Mass of sugar cube:
______________ x _______________ =
.
g
3