Stoichiometry & Chemical Principles Quiz

What is the primary purpose of the mole concept in chemistry?

• To count large numbers of small particles

• To determine atomic number

• To measure density

• To calculate volume

Which type of formula provides the actual number of atoms of each element in a compound?

• Empirical formula

• Molecular formula

• Structural formula

• Stoichiometric formula

What is the total mass of one mole of Ca₃(PO₄)₂?

• 230.2 g

• 310.2 g

• 279.2 g

• 195.2 g

If a compound consists of 42.1% C, 6.5% H, and 51.4% O, what is its empirical formula?

• C₂H₆O₂

• CH₂O

• C₃H₆O₃

• CHO₂

What is the primary characteristic of a limiting reactant in a chemical reaction?

• It is always the substance with the lowest mass

• It determines the maximum amount of product that can be formed

• It is always in excess

• It increases the reaction rate

Which of the following statements is true about percent composition?

• It describes the proportion of each element in a compound

• It is the ratio of products to reactants

• It can only be calculated for ionic compounds

• It is measured in moles

Which of the following correctly represents the combustion reaction of methane (CH₄)?

• CH₄ + 2O₂ → CO + 2H₂O

• CH₄ + O₂ → C + H₂O

• CH₄ + 2O₂ → CO₂ + 2H₂O

• CH₄ + O₂ → CO₂ + H₂

Which gas law is most relevant when performing gas stoichiometry calculations at STP?

• Boyle’s Law

• Charles’s Law

• Ideal Gas Law

• Avogadro’s Law

Which quantity is conserved in every chemical reaction?

• The number of moles of each reactant

• The total mass

• The volume of gases

• The physical state of substances

Which factor must be known to convert from mass to moles?

• The reaction coefficient

• The number of valence electrons

• The molar mass

• The density