Unit 6 Part II - %, EF, MF

Front

What is an empirical formula?

Back

An empirical formula represents the simplest whole-number ratio of atoms of each element in a compound.

Front

How do you determine the molecular formula from the empirical formula?

Back

To find the molecular formula, divide the molar mass of the compound by the molar mass of the empirical formula, then multiply the subscripts in the empirical formula by that ratio.

Front

What is the empirical formula of a compound with the molecular formula C₆H₁₂O₆?

Back

The empirical formula is CH₂O.

Front

How do you calculate percent composition of an element in a compound?

Back

Percent composition = (mass of element in 1 mole of compound / molar mass of compound) x 100%.

Front

What is the percent composition of lithium in lithium chloride (LiCl)?

Back

16.4%.

Front

What is the percent composition of chlorine in calcium chloride (CaCl₂)?

Back

63.89%.

Front

What is the empirical formula of naphthalene (C₁₀H₈)?

Back

The empirical formula is C₅H₄.

Front

If the empirical formula is SO₃ and the molar mass is 240.21 g, what is the molecular formula?

Back

The molecular formula is S₃O₉.

Front

What is the molar mass of the empirical formula CH₂O?

Back

The molar mass is 30.03 g/mol.

Front

If a compound has a molar mass of 180 g and an empirical formula of CH₂O, what is its molecular formula?

Back

The molecular formula is C₆H₁₂O₆.