Name:
Mole and Mole Calculations
Year 12 Science
Ruawai College 2013
The Periodic Table for Level 2 Chemistry
The atomic number of an element indicates how many protons are in the nucleus of an atom of that
element.
1.
What is atomic number of hydrogen, H?
2.
How many protons are in the nucleus of a hydrogen atom?
3.
What is the atomic number of carbon, C?
4.
How many protons are in the nucleus of a carbon atom?
5.
Write a sentence to explain how to work out the number of protons in the nucleus of an
element from the periodic table.
The molar mass of an element indicates how much mass a mole of that atom has. A mole contains
6.02 x 1023 particles. Hydrogen has a molar mass of 1.0 g mol-1.
6.
What is the unit of molar mass?
7.
What is the molar mass of carbon?
8.
What is the molar mass of iron?
9.
What is the molar mass of sodium, Na?
10.
What is the mass, in grams, of one mole of sodium?
11.
How many sodium atoms are in one mole of sodium?
12.
What is the mass, in grams, of 112 moles of sodium?
13.
Write a sentence to explain how to calculate the mass of a certain number of moles of a
substance.
14.
Give your own example for #13.
Remember the molar mass for all elements can be found on the periodic table.
The molar mass of sodium chloride, NaCl, is found by adding the molar mass of Na and the molar
mass of Cl.
M(NaCl)
= M(Na) + M(Cl)
= 23.0 + 35.5
= 58.5 g mol-1
15.
What does M stand for?
16.
What does M(Na) mean?
17.
What is the value of M(Na)?
18.
What does M(Cl) mean?
19.
What is the value of M(Cl)?
20.
What does M(NaCl) mean?
21.
What is the value of M(NaCl)?
22.
Find the molar mass of the following:
a.
atomic iodine (I)
M(I)
=
b.
molecular iodine (I2)
M(I2)
=
c.
aluminium (Al)
M(Al)
=
d.
ethane (C2H6)
M(C2H6) =
e.
copper oxide (Cu2O)
M(Cu2O) =
f.
calcium sulfate (CaSO4) M(CaSO4)=
The relationship between molar mass, mass and amount of substance is shown in the triangle
below:
M is molar mass measured in g mol-1 (read as grams per mole)
m is mass measured in grams
n is amount of substance measured in mol
Rearranging the triangle allows you to perform calculations.
M=m÷n
Example:
m
n=m÷M
m = n x M
The mass of 3.00 mol of neon atoms is 60.6 g.
= n x M
= 3.00 mol x 20.2 g mol-1
= 60.6 g
23.
What is the amount of substance in the example above (amount of neon)?
24.
What is the molar mass of neon?
25.
Where can you find the molar mass of neon?
26.
What equation was used to find the mass of 3.00 mole of neon atoms?
Example:
n
The amount of copper atoms in 5.00 kg of copper is 78.6 mol.
=m÷M
= ( 5 x 1000) g ÷ 63.6 g mol-1
= 78.6 mol
27.
Why is the 5 multiplied by 1000?
28.
Where did the 63.6 g mol-1 come from?
29.
What is the unit for amount of cppper atoms?
30.
What equation was used to find the amount of copper atoms in 5 kg of copper?
31.
Complete the table using the equation
m=nxM
Name
Formula
Iodine atom
I
Amount of
substance, n (mol)
2
Iodine molecule
I2
0.5
Lead nitrate
Pb(NO3)2
1.5
Magnesium iodide
MgI2
0.4
Potassium oxide
K2O
1.2
Aluminium sulfate
Al2(SO4)3
0.3
32.
Molar mass, M
(g mol-1)
Complete the table using the equation
Name
Formula
Iodine molecule
Mass of substance,
m (g)
n =m÷M
Molar mass, M
(g mol-1)
Mass of substance,
m (g)
38.1
Magnesium
carbonate
MgCO3
42.15
Calcium ethanoate
Ca(CH3COO)2
63.24
Sucrose
C12H22O11
17.1
Aluminium sulfate
Copper (ll) sulfate
396.3
CuSO4
31.94
Amount of
substance, n (mol)
Practical
Aim:
To use the equation
Equipment:
safety glasses
n = m ÷ M to calculate mass and amount of substance.
balance
samples
empty container
Method:
Weigh empty container and record mass in the data table . (Assume constant mass for all
containers)
Go to any station and look for the label on plastic container. Record # and formula in data
table.
Weigh sample and record mass in data table.
Calculate the amount of the substance in moles.
Calculate the number of particles in the weighed sample.
Results:
Sample
#
Data Table
Formula
Molar
mass
Mass of
sample +
container
(g)
Mass of
container
(g)
Mass of
sample
(g)
Amount
of
substance
(mol)
Number of
particles
More Exercises:
33.
Calculate the amount (mole) of atoms in 32 g of oxygen gas.
34.
What is the molar mass of atomic chlorine if 20 moles has a mass of 710 g?
35.
What is the mass of 3 moles of carbon atoms?
36.
Calculate the amount of silicon in 0.14 g of silicon.
37.
Calculate the amount of molecular nitrogen in 0.14 g of nitrogen gas.
38.
Calculate the amount of lithium in 0.14 g of lithium.
Extension Practical:
Zinc
Weigh 20 large zinc granules.
m=
M(Zn) =
n(Zn) =
n(Zn) in one granule =
How many granules in one mole of zinc?
Magnesium
Measure the length of the magnesium ribbon and find its mass.
length =
mass =
M(Mg) =
n(Mg) =
What length of ribbon would contain 1 mole of magnesium?
What is the amount of magnesium in 1 metre of magnesium?
Name: Answers
Mole and Mole Calculations
Year 12 Science
Ruawai College 2013
The Periodic Table for Level 2 Chemistry
The atomic number of an element indicates how many protons are in the nucleus of an atom of that
element.
1.
What is atomic number of hydrogen, H?
1
2.
How many protons are in the nucleus of a hydrogen atom?
1
3.
What is the atomic number of carbon, C?
6
4.
How many protons are in the nucleus of a carbon atom?
6
5.
Write a sentence to explain how to work out the number of protons in the nucleus of an
element from the periodic table.
The atomic number of an element is the number of protons in the nucleus of that element’s
nucleus.
The molar mass of an element indicates how much mass a mole of that atom has. A mole contains
6.02 x 1023 particles. Hydrogen has a molar mass of 1.0 g mol-1.
6.
What is the unit of molar mass?
g mol-1
7.
What is the molar mass of carbon?
6 g mol-1
8.
What is the molar mass of iron?
55.9 g mol-1
9.
What is the molar mass of sodium, Na?
23.0 g mol-1
10.
What is the mass, in grams, of one mole of sodium?
23 g
11.
How many sodium atoms are in one mole of sodium?
6.02 x 1023
12.
What is the mass, in grams, of 12 moles of sodium?
23 x 12 = 276 g
13.
Write a sentence to explain how to calculate the mass of a certain number of moles of a
substance.
multiply the number of moles of a substance by the molar mass to get the total mass of
the substance
14.
Give your own example for #13.
Remember the molar mass for all elements can be found on the periodic table.
The molar mass of sodium chloride, NaCl, is found by adding the molar mass of Na and the molar
mass of Cl.
M(NaCl)
= M(Na) + M(Cl)
= 23.0 + 35.5
= 58.5 g mol-1
15.
What does M stand for?
molar mass
16.
What does M(Na) mean?
molar mass of sodium
17.
What is the value of M(Na)?
23 g mol-1
18.
What does M(Cl) mean?
molar mass of chlorine
19.
What is the value of M(Cl)?
35.5 g mol-1
20.
What does M(NaCl) mean?
molar mass of sodium chloride
21.
What is the value of M(NaCl)? 23.0 + 35.5 = 58.5 g mol-1
22.
Find the molar mass of the following:
a.
atomic iodine (I)
M(I)
=
127 g mol-1
b.
molecular iodine (I2)
M(I2)
=
2 x 127 g mol-1
c.
aluminium (Al)
M(Al)
=
27.0 g mol-1
d.
ethane (C2H6)
M(C2H6) =
(2 x 12) + (6 x 1) = 30 g mol-1
e.
copper oxide (Cu2O)
M(Cu2O) =
(2 x 63.6) + 16 = 143.2 g mol-1
f.
calcium sulfate (CaSO4) M(CaSO4)=
40.1 + 32.1 + (4 x 16) = 136.2 g mol-1
The relationship between molar mass, mass and amount of substance is shown in the triangle
below:
M is molar mass measured in g mol-1 (read as grams per mole)
m is mass measured in grams
n is amount of substance measured in mol
Rearranging the triangle allows you to perform calculations.
M=m÷n
Example:
m
n=m÷M
m = n x M
The mass of 3.00 mol of neon atoms is 60.6 g.
= n x M
= 3.00 mol x 20.2 g mol-1
= 60.6 g
23.
What is the amount of substance in the example above (amount of neon)?
24.
What is the molar mass of neon?
20.2 g mol-1
25.
Where can you find the molar mass of neon?
Periodic table
26.
What equation was used to find the mass of 3.00 mole of neon atoms?
Example:
n
3.00 mol
m = n xM
The amount of copper atoms in 5.00 kg of copper is 78.6 mol.
=m÷M
= ( 5 x 1000) g ÷ 63.6 g mol-1
= 78.6 mol
27.
Why is the 5 multiplied by 1000? There are 1000 grams in one kilogram
28.
Where did the 63.6 g mol-1 come from?
29.
What is the unit for amount of copper atoms? mol
30.
What equation was used to find the amount of copper atoms in 5 kg of copper? n = m ÷ M
molar mass of copper / periodic table
31.
Complete the table using the equation
Name
Formula
Iodine atom
I
Iodine molecule
I2
Lead nitrate
m=nxM
Molar mass, M
(g mol-1)
254
Mass of substance,
m (g)
2 x 127 = 254
Amount of
substance, n (mol)
2
254
0.5 x 254 = 127
0.5
Pb(NO3)2
331.0
1.5 x 331 = 496.5
1.5
Magnesium iodide
MgI2
278.3
0.4 x 278.3 =
111.32
0.4
Potassium oxide
K2O
94.2
1.2 x 94.2 = 113.04
1.2
Aluminium sulfate
Al2(SO4)3
342.3
0.3 x 342.3 =
102.69
0.3
32.
Complete the table using the equation
Name
Formula
Iodine molecule
I2
Magnesium
carbonate
MgCO3
Calcium ethanoate
n =m÷M
Molar mass, M
(g mol-1)
254
Mass of substance,
m (g)
38.1
Amount of
substance, n (mol)
38.1 ÷ 254 = 0.15
84.3
42.15
42.15 ÷ 84.3 = 0.50
Ca(CH3COO)2
158.1
63.24
63.24 ÷158.1 = 0.40
Sucrose
C12H22O11
342.0
17.1
17.1 ÷ 342.1 = 0.05
Ammonium sulfate
(NH4)2SO4
132.1
396.3
396.3 ÷ 132.1 = 3.0
Copper (ll) sulfate
CuSO4
159.7
31.94
31.94 ÷ 159.7 =
0.20
Practical
Aim:
To use the equation
Equipment:
safety glasses
n = m ÷ M to calculate mass and amount of substance.
balance
samples
empty container
Method:
Weigh empty container and record mass in the data table . (Assume constant mass for all
containers)
Go to any station and look for the label on plastic container. Record # and formula in data
table.
Weigh sample and record mass in data table.
Calculate the amount of the substance in moles.
Calculate the number of particles in the weighed sample.
Results:
Sample
#
Data Table
Formula
Molar
mass
Mass of
sample +
container
(g)
Mass of
container
(g)
Mass of
sample
(g)
Amount
of
substance
(mol)
Number of
particles
More Exercises:
33.
Calculate the amount (mole) of atoms in 32 g of oxygen gas.
32 ÷ 16
2 mol
34.
What is the molar mass of atomic chlorine if 20 moles has a mass of 710 g?
710 ÷ 20
35.5 g mol-1
35.
What is the mass of 3 moles of carbon atoms?
3 x 12
36 g
36.
Calculate the amount of silicon in 0.14 g of silicon.
0.14 ÷ 28
0.005 mol
37.
Calculate the amount of molecular nitrogen in 0.14 g of nitrogen gas.
0.14 ÷ 28
0.005 mol
38.
Calculate the amount of lithium in 0.14 g of lithium.
0.14 ÷ 7
0.02 mol
Extension Practical:
Zinc
Weigh 20 large zinc granules.
m=
M(Zn) =
n(Zn) =
n(Zn) in one granule =
How many granules in one mole of zinc?
Magnesium
Measure the length of the magnesium ribbon and find its mass.
length =
mass =
M(Mg) =
n(Mg) =
What length of ribbon would contain 1 mole of magnesium?
What is the amount of magnesium in 1 metre of magnesium?