This video tutorial covers the basics of chemical formulas, including the differences between elements and compounds, the purpose and types of chemical formulas, and the concept of oxidation numbers. It also explains phase abbreviations used in chemical formulas. The tutorial provides examples and rules for assigning oxidation numbers and discusses molecular and empirical formulas.

What is an element composed of?

• Multiple types of atoms

• A mixture of compounds

• One type of atom

• Two or more different elements

Which of the following is a correct definition of a compound?

• A substance composed of one type of atom

• A mixture of different substances

• A substance that can be broken down into simpler substances by chemical means

• A pure substance composed of two or more different elements chemically combined in a fixed proportion

What does a chemical formula tell us?

• The physical state of a compound

• The taste of a compound

• The number and kind of atoms in a compound

• The color of a compound

Which of the following is a molecular formula?

• Fe2O3

• CaCO3

• SO2

• NaCl

What is the empirical formula for C8H10N4O2?

• C4H5N2O

• C8H10N4O2

• CH2N

• C2H5N

What is the oxidation number of an atom in a free element?

• +2

• -1

• +1

• 0

In most compounds, what is the oxidation number of oxygen?

• -1

• +1

• +2

• -2

What is the oxidation number of sulfur in SO4^2-?

• -2

• +6

• +2

• +4

What does the phase abbreviation (aq) indicate?

• A solid state

• A liquid state

• Dissolved in water

• A gas state

Which phase abbreviation represents a solid?

• (aq)

• (l)

• (s)

• (g)