Chemistry Review

Front

What is an empirical formula?

Back

An empirical formula is the simplest whole-number ratio of moles of elements in a compound.

Front

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

Back

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

Front

What is the percent composition by mass of sulfur (S) in MgSO4?

Back

26.64%.

Front

What is the molecular formula for glycerol with a molar mass of 92.09 g/mol and percent composition of 39.12% C, 8.75% H, and 51.12% O?

Back

C3H8O3.

Front

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

Back

C3H8.

Front

How do you determine the empirical formula from percent composition?

Back

Convert percent to grams, then to moles, and find the simplest whole-number ratio.

Front

What is the formula for calculating molar mass?

Back

Molar mass = sum of the atomic masses of all atoms in a molecule.

Front

What is the percent composition by mass of chlorine (Cl) in HClO3?

Back

42%.

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.

Front

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

Back

Multiply the subscripts in the empirical formula by a whole number to match the molar mass.