Mole Ratio and Stoichiometry Exam Review

Dr. David Block reviews a practice unit exam covering mole ratios, stoichiometry, and types of chemical reactions. The video includes calculations of moles of atoms in compounds, understanding molecular mass, determining mole ratios, calculating percentage by mass, and identifying reaction types. It emphasizes the importance of balancing equations and the conservation of mass in chemical reactions.

How many total moles of atoms are present in NH4)2SO4?

• 15 moles

• 20 moles

• 8 moles

• 10 moles

What is the molecular formula for ozone?

• O2

• O3

• O4

• O

What is the mole ratio of H2 to HF in the reaction discussed?

• 2:1

• 1:2

• 2:3

• 1:1

What is the closest percentage by mass of bromine in aluminum bromide?

• 89.5%

• 89.88%

• 89.88%

• 90.5%

What is the percent composition by mass of hydrogen in NH4HCO3?

• 7.59%

• 10%

• 6.33%

• 5%

What percentage of a hydrate crystal's mass is water?

• 8.5%

• 12%

• 9.75%

• 10%

Which type of reaction is formed when two substances combine to become one?

• Decomposition

• Synthesis

• Single Replacement

• Double Replacement

What is a classic example of a double replacement reaction?

• A + XY -> AX + Y

• AB -> A + B

• A + B -> AB

• AB + XY -> AY + XB

Which equation illustrates the conservation of mass?

• 2H2 + 2Cl2 -> 2HCl

• H2 + Cl2 -> 2HCl

• 2H2 + O2 -> 2H2O

• 2H2 + 2O2 -> 2H2O

What is the correct formula for the product represented by X in the reaction with sodium and water?

• NaHCO3

• H2O

• Na2O

• NaOH