Question

How many grams of sodium is present in 2 moles?

Answer 1

Approx. `46` `g`.

Explanation:

Sodium metal has a molar mass of `22.99` `g*mol^-1`.

Thus if there is a `2` `mol` quantity the mass is:

`2*cancel(mol)xx22.99*g*cancel(mol^-1)` `=` `??` `g`.

How did I know that sodium metal has such a molar mass? Because I have access to a Periodic Table, which gives me the molar mass of not just sodium but of every other known element.

Can you take the Table into an exam? Of course you can, or at least 1 will be provided. In every exam in Physics and Chemistry you ever sit, you must be provided a copy of the Periodic Table. It is up to you to learn how to use it effectively.

Answer 2

2 moles `xx` molar mass of sodium = ??

Explanation:

Assume that:
n = number of moles
m = mass of substance
M = molar mass (equivalent to atomic weight on the periodic table)

`n = m -: M`

2 moles (n) has been given to you.

The next step is to find the molar mass (M) of Na. If you refer to your periodic table, the molar mass of Na (sodium) is 23.0 g/mol.

Now you have to find the mass (m).
The mass of sodium is:
[m = 23.0 g/mol `xx` 2 moles] = 46.0 grams of sodium is present in 2 moles