LT#5&6: Finding Formulas

Question 1

Define Molecular Formula

Answer 1

Shows the actual number of atoms that make up each molecule or formula unit.

Question 2

Define Empirical Formula

Answer 2

Shows the lowest whole number ratio (simplest formula).

Question 3

Why are the empirical and molecular formulas for an ionic compound always the same?

Answer 3

Ionic compounds are always written in lowest terms.

Question 4

What are the steps for determining an Empirical Formula?

Answer 4

1. Find the mass of each piece of the formula
2. Find the moles of each piece
3. Divide each by the lowest number
4. Multiply (by 2 – 6) to make a whole number if needed
5. Write empirical formula

Question 5

Define Hydrate

Answer 5

An ionic compound with water molecules trapped inside their crystals.

Question 6

Define Anhydrous

Answer 6

An ionic compound that has been dried and contains no water molecules.

Question 7

What is a CH Analyzer?

Answer 7

Burns a hydrocarbon sample in complete combustion reaction. Collects carbon dioxide and water separately. Since the only source of carbon and hydrogen is the unknown compound, we can use conversion factors to find the mass of C and H in the original compound. Then find the empirical formula.

Question 8

How do you change an empirical into a molecular formula?

Answer 8

Find molecular multiplier the multiply empirical formula

Question 9

Define Percent Composition

Answer 9

List of mass percents of each element in a compound. Each chemical has unique ratio that can be used to identify compounds.