Practice Questions

Stoichiometric calculations depend on the coefficients of a balanced equation because they represent mole ratios. Physical states, temperature, and reaction rate are not sufficient for quantitative calculations. Concept tested: Importance of balanced equations in stoichiometry.

At the same conditions of temperature and pressure, gas volumes follow mole ratios. One volume of O₂ produces two volumes of gaseous H₂O. Thus, 44.8 L O₂ forms 89.6 L H₂O(g). Concept tested: Gas volume ratios at STP.

Sodium is an element consisting of atoms, so one mole contains Avogadro's number of atoms, not molecules. Concept tested: Representative particles.

According to the balanced equation, 2 moles of KClO₃ produce 3 moles of O₂. Therefore, 4 moles produce 6 moles of O₂. Concept tested: Stoichiometric calculations using balanced equations.

The balanced equation shows a 1 : 1 mole ratio between CH₄ and CO₂. Thus, 3 moles of methane produce 3 moles of carbon dioxide. Concept tested: Mole ratio application.

At STP (0°C and 1 atm), one mole of any ideal gas occupies 22.4 L. Values like 24.0 L apply approximately at room temperature, not STP. Concept tested: Molar volume of gases.

The molar mass of H₂O is 18 g mol⁻¹. Therefore, 18 g represents exactly one mole. Concept tested: Mass-mole relationship.

Avogadro's number is 6.02 × 10²³ representative particles per mole. The other values are incorrect multiples or fractions. Concept tested: Avogadro's constant.

From the equation, 1 mole of N₂ reacts with 3 moles of H₂. Therefore, 2 moles of N₂ require 6 moles of H₂. Concept tested: Stoichiometric mole calculations.

The coefficients in a balanced equation represent mole ratios. Here, 2 moles of H₂ react with 1 mole of O₂. The other ratios do not match the balanced equation. Concept tested: Mole ratio from a balanced equation.