Stoichiometry

What is the primary purpose of stoichiometry in chemistry?

• To study the rates of chemical reactions.

• To measure the quantities of reactants and products in chemical reactions.

• To analyze the structure of atoms and molecules.

• To determine the energy changes during a reaction.

Why is a balanced chemical equation essential for stoichiometric calculations?

• It indicates the physical states of reactants and products.

• It provides the mole ratios between reactants and products.

• It determines the activation energy of the reaction.

• It describes the reaction mechanism.

If 24.6 grams of methane (CH₄) are completely combusted with sufficient oxygen, what mass of water (H₂O) is expected to be produced? (Molar mass of CH₄ = 16.05 g/mol, H₂O = 18.02 g/mol) Balanced equation: CH₄ + 2O₂ → CO₂ + 2H₂O

• 16.05 g H₂O

• 24.6 g H₂O

• 55.2 g H₂O

• 32.00 g H₂O

In a chemical reaction, what defines a limiting reactant?

• The reactant with the largest molar mass.

• The reactant that is completely consumed and determines the maximum amount of product formed.

• The reactant that is present in excess after the reaction is complete.

• The reactant that has the highest concentration.

In a chemical reaction, if 10.0 g of methane (CH4) and 10.0 g of oxygen (O2) are reacted, which reactant limits the amount of carbon dioxide (CO2) produced? (Balanced equation: CH4 + 2O2 → CO2 + 2H2O)

• Methane (CH4)

• Oxygen (O2)

• Carbon Dioxide (CO2)

• Water (H2O)

A chemical reaction is predicted to produce 6.88 g of carbon dioxide (CO2). If the actual amount of CO2 collected from the experiment is 6.19 g, what is the percent yield of the reaction?

• 85.0%

• 90.0%

• 95.0%

• 100.0%

How many liters of water (H2O) can be produced from 20.0 L of methane (CH4) at Standard Temperature and Pressure (STP)? (Balanced equation: CH4 + 2O2 → CO2 + 2H2O)

• 10.0 L

• 20.0 L

• 30.0 L

• 40.0 L

In a titration, 30.0 mL of a 1.00 M sodium hydroxide (NaOH) solution is used to neutralize an unknown amount of oxalic acid (H2C2O4). How many grams of oxalic acid were present? (Molar mass of H2C2O4 = 90.0 g/mol. Balanced equation: 2NaOH + H2C2O4 → Na2C2O4 + 2H2O)

• 0.675 g

• 1.35 g

• 2.70 g

• 4.50 g