The Mole

Question 1

What is the mole?

Answer 1

• Symbol: mol.
• Represents a certain number of things.
• A dozen represents 12.
• A gross represents 144.
• A mol represents 6.02 X 10^23.
• 6.02 X 10^23 is called Avogadro’s number.
• This is the number of atoms in 12.00g of carbon-12.
• Avogadro’s number is so large because an atom is so small.
• 1 mole of a substance is an observable amount.
• 1.0 mol=6.02 X 10^23 atoms or molecules.
• 0.5 mol=3.01 X 10^23 atoms or molecules.
• 2.0 mol=1.20 X 10^24 atoms or molecules.

Question 2

How do you use the mole?

Answer 2

-The atomic mass is given on your periodic table to the nearest one-hundredth of a gram.
-From this point on the atomic mass will be known as molar mass.
Molar mass is the mass(in grams) of one mole(6.02 X 10^23 particles) of a substance.
-1 mole of sodium atoms has a mass of 22.99g.
-Therefore sodium has a molar mass of 22.99g/mol.

Question 3

What is molar mass of molecules?

Answer 3

Because molecules are particles, they can also be measured in moles.
If you had 1 mole of H2O(l)=6.02 X 10^23 molecules of H2O. Each molecule of water is made of 2 atoms hydrogen and 1 atom of oxygen.
6.02X10^23 H2O -> 1.20X10^24 H + 6.02X10^23 O.
This means the mass of 1 mole of water is equal to the mass of 2 moles of hydrogen and 1 mole of oxygen.

Question 4

How do you convert mass to moles?

Answer 4

m
n=—-
M
The number of moles(n) present in a given mass(m) is equal to the mass divided by the molar mass(M).

Question 5

How do you calculate moles to mass?

Answer 5

m=nM

To calculate the mass present in a given number of moles we need to rearrange our formula as follows.