The following information applies to parts A and B. 7. Sodium metal reacts with oxygen gas according — Thermodynamics, Enthalpy of Formation, Calorimetry, Lattice Energy, Coulomb's Law Chemistry Question
Problem Context
The following information applies to parts A and B.
7. Sodium metal reacts with oxygen gas according to Equation 1.
Equation 1: 4 Na(s) + O2(g) → 2 Na2O(s) ΔH°_rxn = -828 kJ/mol_rxn
Standard enthalpies of formation are provided in Table 1.
A. Based on the information given, calculate the value of ΔH°_f for Na2O(s). Show the work that leads to your answer.
B. An 18.4 g sample of Na(s) reacts with 12.8 g of O2(g) according to Equation 1. Calculate the total amount of heat, in kilojoules, released during this process. Show the work that leads to your answer.
C. Lattice enthalpy can be defined as the energy required to separate an ionic crystal into gaseous ions. Rb2O(s) and Na2O(s) have similar crystal structures, and their lattice enthalpies are given in Table 2.
Using Coulomb’s law, explain why the lattice enthalpy of Rb2O(s) is smaller than that of Na2O(s).