Topic 15: Empirical Formula, Video A: What's an Empirical Formula?

Question 1

What is an empirical formula?

Answer 1

Formula based on mole ratio in its simplest form. Simplest whole number ratio of atoms within a molecule.

Question 2

What is the molecular formula?

Answer 2

Based on the mole ratio and and the total molar mass. Actual whole number atomic (mole) ratio of a compound.

Question 3

How do you calculate the empircal formual of a compound?

Answer 3

1. Convert grams of each element to moles using the molar mass.
2. Calculating the simplest integer moles ratio.

Question 4

How do you calculate the molecular formula of a molecule?

Answer 4

1. MW of a given compound.
2. Determine molecular mass of EF. (add molecular weights of all atoms.)
3. Ratio of MW to mass of EF. (Divide EF molecular weight by MW.
4. Multiply EF by Ratio.