You water some plants with 4 different types of water (salt water, regular water, sugar water and distilled water). After a two-week period, the height of the plants is measured.

What mass of iron must be in a hot pack to provide -335kj of heat when the iron reacts with oxygen and is converted to iron (111) oxide according to the following thermochemical equation? 2fe(s) + 1.5o2(g)—> fe2o3(s) delta h= -824.2kj/mol