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.

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answer is: naturally occurring solid, inorganic compound or element is mineral.

minerals usually have crystalline form, that means than crystal constituents (atoms, molecules or ions) are arranged in a highly ordered microscopic structure, forming a crystal lattice that extends in all directions.

for example magnetite is a mineral of iron oxide (fe₂o₃).

calcite is a carbonate mineral and the most stable polymorph of calcium carbonate (caco₃).

dolomite is an   carbonate mineral composed of calcium magnesium carbonate (camg(co₃)₂).

your answer is a. the enthalpy of formation for a pure element in its standard state is always positive.

what are the statements