Moles and Avogadro’s Numbers

Carbon has a molar mass of 12 g mol⁻¹. Thus, 24 g = 2 moles of C, producing 2 moles (44.8 L) of CO₂ at STP. Concept tested: Integrated mass-mole-volume calculation.

Balanced equation coefficients represent mole ratios and serve as conversion factors in stoichiometric calculations. Concept tested: Stoichiometric conversion factors.

Gas volumes at the same conditions follow mole ratios. Three volumes of H₂ produce two volumes of NH₃. Therefore, 67.2 L H₂ (3 × 22.4 L) yields 44.8 L NH₃ (2 × 22.4 L). Concept tested: Gas volume stoichiometry at STP.

The balanced equation shows that 3 moles of Cl₂ produce 2 moles of AlCl₃. Therefore, 6 moles of Cl₂ produce 4 moles of AlCl₃. Concept tested: Mole ratio from a balanced equation.

Three moles contain 3 × 6.02 × 10²³ = 1.81 × 10²⁴ molecules. The other values represent fewer moles. Concept tested: Mole-to-particles conversion.

According to the balanced equation, 2 moles of HgO produce 1 mole of O₂. Therefore, 8 moles of HgO produce 4 moles of O₂. Concept tested: Stoichiometric calculations.

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.

The balanced equation shows a 2 : 2 ratio between Na and NaCl, which simplifies to 1 : 1. Therefore, 5 moles of Na produce 5 moles of NaCl. Concept tested: Mole ratio from a balanced equation.

The balanced equation indicates a 1 : 1 mole ratio between CaCO₃ and CO₂. Therefore, 2.5 moles of CaCO₃ yield 2.5 moles of CO₂. Concept tested: Stoichiometric mole calculations.

One mole contains 6.02 × 10²³ molecules. Therefore, 0.5 mole contains half of this number, 3.01 × 10²³ molecules. Concept tested: Avogadro's number.

At STP, one mole of any ideal gas occupies 22.4 L. Thus, 2.5 × 22.4 = 56.0 L. Concept tested: Molar volume at STP.

According to the balanced equation, 2 moles of Mg react with 1 mole of O₂. Therefore, 4 moles of Mg require 2 moles of O₂. Concept tested: Mole ratio application.

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.

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.

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

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

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 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.

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.