Empirical and Molecular Formula Practice Test

Front

What is an empirical formula?

Back

The empirical formula is the formula with the lowest whole number ratios of the elements in a compound.

Front

What is a molecular formula?

Back

The molecular formula shows how many of each type of atom are present in a single molecule.

Tags

NGSS.MS-PS1-1

Front

How do you determine the empirical formula from percentage composition?

Back

Convert the percentages to grams, then to moles, and simplify the mole ratio to the smallest whole numbers.

Front

Which pair has the same empirical formula: NaCrO4 and Na2Cr2O7, or C2H4O2 and C6H12O6?

Back

C2H4O2 and C6H12O6 have the same empirical formula.

Front

What is the empirical formula for a compound with 72.2% magnesium and 27.8% nitrogen?

Back

The empirical formula is Mg3N2.

Front

What is the empirical formula for a compound with 81.82% carbon and 18.18% hydrogen?

Back

The empirical formula is C3H8.

Front

If a compound has an empirical formula of C2OH4 and a molar mass of 88 g/mol, what is its molecular formula?

Back

The molecular formula is C4O2H8.

Front

What is the first step in finding the empirical formula from a molecular formula?

Back

Identify the number of each type of atom in the molecular formula.

Front

How do you convert grams to moles?

Back

Divide the mass of the substance by its molar mass.

Front

What is the significance of the empirical formula in chemistry?

Back

It provides the simplest ratio of elements in a compound, which is useful for understanding its composition.