Name: Jose Rivera Rodriguez Date: 02/24/20 – 02/25/20
Activity: Moles, Avogadro, and Molar Mass
Prior Knowledge Questions
1. In the image, note a dozen eggs, a dozen donuts and a dozen
roses. How many of each item do you have? 12 eggs, 12
donuts, and 12 roses.
2. Would a dozen of each object have the same mass? No
3. Suppose you have a dozen silver atoms, a dozen oxygen atoms, and a dozen lithium atoms.
Even though you have the same number of each, will they all have the same mass? Explain.
They will not all have the same mass because although there may be an equal amount
of each one, they don’t all weigh the same or take up the same amount of space.
Gizmo Warm-up
On the AVOGADRO CONSTANT tab, place the copper (Cu) atom
on the nano-balance on the left, which will show the average atomic
mass of copper rather than the mass of a single copper atom.
1. What is the average mass of a copper atom? 63.546 u
The unit “u” refers to unified atomic mass units. (Officially, 1 u is one-twelfth the mass of a
C-12 atom.)
2. To know how many atoms are in a gram of copper, use the larger balance on the right.
Press Add atoms to put a scoop of atoms in the weighing dish, and keep adding until the
balance registers between 1 and 2 grams. If you don’t seem to be making much progress,
adjust the exponent using the slider, which will make the scoop size bigger.
How many atoms did you need to add? 9.6 x 10^21 atoms of copper
, Get the Gizmo ready:
Activity A:
Select the AVOGADRO CONSTANT tab.
Molar Mass Turn on Show hints and check that Copper (Cu)
is selected.
Introduction: Since atoms are so tiny, chemists have devised a unit known as the mole. A
mole represents a macroscopic quantity of matter that can be used in the laboratory. One mole
of any element has the same mass in grams as its atomic mass in u.
Question: How many particles are in a mole?
1. Explore: Note the average atomic mass of copper on the nano-balance. Add atoms to the
larger balance until it registers the same number (in g) as the reading on the nano-balance
(in u). Use the Exponent slider to help get the correct amount. Stop adding atoms when the
readings on both balances match exactly (to the nearest 0.001 g).
How many atoms did you need to add? 6.0221 x 10^23 atoms of copper
2. Explore: Repeat the same procedure with carbon, and aluminum.
A. For each element, how many atoms did you need to add? Carbon: 6.022 x 10^23
atoms and Aluminum: 6.022 x 10^23
B. What do you notice about the number of atoms in one mole? The number of atoms
for one mole is the same no matter the element.
3. Discover: In each case, you measured out one mole of atoms, since the mass of one mole
of any element, in grams, is equal to its atomic mass, in u. One mole of any element
contains the same number of atoms, a number known as the Avogadro constant.
What is the exact value of the Avogadro constant? 6.02214076 x 10^23
4. Compare: The number of grams in a mole (g/mol) is known as its molar mass, and has the
same numerical value as an element’s atomic mass (in u). Use the Gizmo to find the atomic
and molar mass of the following elements. Use proper units.
Sulfur: Atomic mass 32.065 u Molar mass 32.065 G/Mol
Aluminum: Atomic mass 26.982 u Molar mass 26.982 G/Mol
5. Experiment: Select Copper(I) oxide, Cu2O. Note that Cu2O is a compound composed of
different types of atoms bonded together. Place the Cu2O molecule on the nano-balance.
A. What is the molecular mass of Cu2O? 143.091 G/Mol
Activity: Moles, Avogadro, and Molar Mass
Prior Knowledge Questions
1. In the image, note a dozen eggs, a dozen donuts and a dozen
roses. How many of each item do you have? 12 eggs, 12
donuts, and 12 roses.
2. Would a dozen of each object have the same mass? No
3. Suppose you have a dozen silver atoms, a dozen oxygen atoms, and a dozen lithium atoms.
Even though you have the same number of each, will they all have the same mass? Explain.
They will not all have the same mass because although there may be an equal amount
of each one, they don’t all weigh the same or take up the same amount of space.
Gizmo Warm-up
On the AVOGADRO CONSTANT tab, place the copper (Cu) atom
on the nano-balance on the left, which will show the average atomic
mass of copper rather than the mass of a single copper atom.
1. What is the average mass of a copper atom? 63.546 u
The unit “u” refers to unified atomic mass units. (Officially, 1 u is one-twelfth the mass of a
C-12 atom.)
2. To know how many atoms are in a gram of copper, use the larger balance on the right.
Press Add atoms to put a scoop of atoms in the weighing dish, and keep adding until the
balance registers between 1 and 2 grams. If you don’t seem to be making much progress,
adjust the exponent using the slider, which will make the scoop size bigger.
How many atoms did you need to add? 9.6 x 10^21 atoms of copper
, Get the Gizmo ready:
Activity A:
Select the AVOGADRO CONSTANT tab.
Molar Mass Turn on Show hints and check that Copper (Cu)
is selected.
Introduction: Since atoms are so tiny, chemists have devised a unit known as the mole. A
mole represents a macroscopic quantity of matter that can be used in the laboratory. One mole
of any element has the same mass in grams as its atomic mass in u.
Question: How many particles are in a mole?
1. Explore: Note the average atomic mass of copper on the nano-balance. Add atoms to the
larger balance until it registers the same number (in g) as the reading on the nano-balance
(in u). Use the Exponent slider to help get the correct amount. Stop adding atoms when the
readings on both balances match exactly (to the nearest 0.001 g).
How many atoms did you need to add? 6.0221 x 10^23 atoms of copper
2. Explore: Repeat the same procedure with carbon, and aluminum.
A. For each element, how many atoms did you need to add? Carbon: 6.022 x 10^23
atoms and Aluminum: 6.022 x 10^23
B. What do you notice about the number of atoms in one mole? The number of atoms
for one mole is the same no matter the element.
3. Discover: In each case, you measured out one mole of atoms, since the mass of one mole
of any element, in grams, is equal to its atomic mass, in u. One mole of any element
contains the same number of atoms, a number known as the Avogadro constant.
What is the exact value of the Avogadro constant? 6.02214076 x 10^23
4. Compare: The number of grams in a mole (g/mol) is known as its molar mass, and has the
same numerical value as an element’s atomic mass (in u). Use the Gizmo to find the atomic
and molar mass of the following elements. Use proper units.
Sulfur: Atomic mass 32.065 u Molar mass 32.065 G/Mol
Aluminum: Atomic mass 26.982 u Molar mass 26.982 G/Mol
5. Experiment: Select Copper(I) oxide, Cu2O. Note that Cu2O is a compound composed of
different types of atoms bonded together. Place the Cu2O molecule on the nano-balance.
A. What is the molecular mass of Cu2O? 143.091 G/Mol
