A student places 0.50 g of clean steel wool into an open crucible
CHEMISTRY · Single correct · AP · Chemistry · Chemical Reactions · Chemical Reactions
Problem
A student places 0.50 g of clean steel wool into an open crucible, heats it strongly in air for 10 min, allows it to cool, and finds that the combined mass has increased to 0.64 g. Which conclusion is most strongly supported by these results?
(a) A physical change occurred because oxygen was merely adsorbed on the surface of the steel wool, increasing its mass.
(b) A chemical change occurred because nitrogen from the air combined with iron in the steel wool to form an iron nitride.
(c) A chemical change occurred because oxygen from the air combined with iron in the steel wool, increasing its mass.
(d) A chemical change occurred because moisture from the air condensed on the hot steel wool as it cooled, increasing the mass.