chapter 7

Front

What is percent composition?

Back

Percent composition is the percentage by mass of each element in a compound.

Front

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

Back

To calculate percent composition, divide the mass of the element in one mole of the compound by the molar mass of the compound, then multiply by 100.

Front

What is an empirical formula?

Back

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

Front

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

Back

To find the empirical formula, divide the subscripts in the molecular formula by their greatest common divisor.

Front

What is the molar mass of a compound?

Back

The molar mass is the mass of one mole of a substance, typically expressed in grams per mole (g/mol).

Front

How do you convert moles to grams?

Back

To convert moles to grams, multiply the number of moles by the molar mass of the substance.

Front

What is the significance of a half in a ratio when determining empirical formulas?

Back

A half in a ratio indicates that you should multiply all ratios by 2 to obtain whole numbers.

Front

What is the formula for calculating the mass percent of an element in a compound?

Back

Mass percent = (mass of element in 1 mole of compound / molar mass of compound) x 100.

Front

What is the empirical formula for C2H4O2 and C6H12O6?

Back

The empirical formula for both is CH2O.

Front

How do you find the mass of a substance from moles?

Back

Mass = moles x molar mass.