The thermite reaction is a reaction between solid iron(III) oxide and solid aluminum to make aluminum oxide and elemental iron. Usually the reactants are fine powders, to increase the contact between them. The reaction is so exothermic that the iron product is initially a liquid (melting point of iron is 1536 °C).

(a) Write a balanced chemical reaction for the thermite reaction.

(b) Identify the oxidizing agent and the reducing agent.

(c) Use the ΔH^°_f data in Appendix G to determine the ΔH_rxn for the thermite reaction.

(d) If all of the energy given off by the reaction were absorbed by the products, what would be the temperature change of the products, assuming that their specific heats did not change with temperature? Is this temperature change enough to melt the iron? The specific heat of aluminum oxide is 79.5 J/mol · K, and the specific heat of iron is 25.2 J/mol · K.

(e) In the solid form, iron exists as a body-centered cubic unit cell with a cell parameter a of 286.64 pm. What is the density of iron?

(f) In the solid form, aluminum exists as a face-centered cubic unit cell with a cell parameter a of 404.9 pm. What is the density of aluminum?

(g) Does either iron or aluminum exist as a closed packed crystal?

(h) At its melting point, iron has a vapor pressure of approximately 0.750 torr. If the balanced thermite reaction were to occur in molar quantities, what volume would be necessary for all of the iron to be in the vapor phase if the temperature were the melting point of iron?

(i) A similar reaction uses chromium(III) oxide instead of iron(III) oxide as a reactant, and chromium metal is a product. What is the ΔH_rxn for this reaction?