Ortable hot packs are available for skiers and other people engaged in other outdoor activities in a cold climate. the air-permeable paper packet contains a mixture of powdered iron, sodium chloride, and other components, all moistened by a little water. the exothermic reaction that produces the heat is a very common one, the rusting of iron: 4fe(s) + 3o2(g) → 2fe2o3(s) when the outside plastic envelope is removed, o2 molecules penetrate the paper, causing the reaction to begin. a typical packet contains 250. g of iron to warm your hands or feet for up to 4 hours. calculate the amount of heat (in kj) associated with this reaction.

A0.10 m aqueous solution of sodium sulfate is a better conductor of electricity than a 0.10 m aqueous solution of sodium chloride. which of the following best explains this observation? (a) sodium sulfate is more soluble in water than sodium chloride. (b) sodium sulfate has a higher molar mass than sodium chloride. (c) to prepare a given volume of 0.10 m solution, the mass of sodium sulfate needed is more than twice the mass of sodium chloride needed. (d) more moles of ions are present in a given volume of 0.10 m sodium sulfate than in the same volume of 0.10 m sodium chloride. (e) the degree of dissociation of sodium sulfate in solution is significantly greater than that of sodium chloride.