Chemistry Exam Review #1

Front

What is the percent by mass of oxygen in CO₂?

Back

To calculate the percent by mass of oxygen in CO₂, use the formula: (mass of oxygen / total mass of CO₂) x 100. CO₂ has 2 oxygen atoms (16 g each) and 1 carbon atom (12 g), so the total mass is 12 + 32 = 44 g. Percent by mass of oxygen = (32/44) x 100 ≈ 72.73%.

Front

What is the chemical formula for sodium sulfate?

Back

The correct chemical formula for sodium sulfate is Na₂SO₄.

Front

What type of bond forms between nonmetals?

Back

Covalent bonds form between nonmetals.

Front

Why are iron filings preferred over an iron nail in reactions?

Back

Iron filings are used instead of an iron nail to increase the surface area of the reaction, allowing for a faster reaction rate.

Front

What type of chemical reaction is represented by the equation 2C₄H₁₀ + 13O₂ → 8CO₂ + 10H₂O?

Back

This equation represents a combustion reaction.

Front

Define combustion reaction.

Back

A combustion reaction is a chemical reaction that occurs when a substance combines with oxygen, releasing energy in the form of light or heat.

Front

What is the molecular formula for sulfur dioxide?

Back

The molecular formula for sulfur dioxide is SO₂.

Front

What is the difference between ionic and covalent bonds?

Back

Ionic bonds involve the transfer of electrons from one atom to another, typically between metals and nonmetals, while covalent bonds involve the sharing of electrons between nonmetals.

Front

What is the role of a catalyst in a chemical reaction?

Back

A catalyst increases the rate of a chemical reaction without being consumed in the process.

Front

What is the balanced equation for the combustion of propane (C₃H₈)?

Back

The balanced equation for the combustion of propane is C₃H₈ + 5O₂ → 3CO₂ + 4H₂O.