8.4 Empirical and Molecular Formulas

Question 1

Formulas for ionic compounds are…

Answer 1

ALWAYS empirical formulas.

Question 2

Empirical formulas are always written with…

Answer 2

the simplest set of whole numbers.

Question 3

Finding the empirical formula from experimental data:

Answer 3

1) Convert the mass of each element into moles.

2) Divide each number by the smaller number.

Question 4

Finding the empirical formula from percent composition:

Answer 4

1) Choose a sample size (recommend 100. g) and multiply it by each of the percentages.
2) Convert the mass of each element into moles.
3) Divide the numbers by the smallest number.
4) If the results are not whole numbers, you must multiply by some factor that will produce a whole number ratio.

Question 5

SWNR

Answer 5

simplest whole number ratio

Question 6

Empirical formulas

Answer 6

A formula indicating the simplest whole number ratio of each kind of atom contained in a molecule.

Question 7

Molecular formulas

Answer 7

A formula indicating the actual number of each kind of atom contained in a molecule.

Question 8

Finding molecular formulas:

Answer 8

1) Determine the empirical formula.
2) Divide the formula mass into the molecular mass.
3) Multiply the empirical formula by the result.