1.3: Elemental Composition of Pure Substances

Question 1

Pure Substance

Answer 1

-matter that has a fixed composition and distinct properties
-element or compound

Question 2

Law of Definite Proportion

Answer 2

-law that states that the elemental composition of a substance is always the same
-ratio of masses of the constituent elements in any pure sample of that compound is always the same

Question 3

Formula Weight (FW)

Answer 3

-ionic
-the sum of the atomic weights for the atoms in a chemical formula

Question 4

Molecular Weight (MW)

Answer 4

-covalent
-the sum of the atomic weights for the atoms in a molecule

Question 5

Percent Composition

Answer 5

-percent of the total mass of the compound that is due to that component
-% composition = (mass due to specific component / total molar mass of compound) x 100

Question 6

Empirical Formula

Answer 6

a chemical formula showing the simplest ratio of elements in a compound

Question 7

Chemical / Molecular Formula

Answer 7

actual ratio of atoms of each element in a compound