Question

question 11: an iron (fe) nail is left outside in the rain and is exposed to oxygen (o2) in the air. after some time, rust (fe2o3) forms on the nail. this process is modeled by the chemical equation shown. 4fe + 3o2 → 2fe2o3 what process is taking place, and what happens to the mass of the nail after rusting? a this is a physical change because the rust can be scraped off, leaving the nail with the same mass as before the rust formed. b this is a chemical reaction but mass is not conserved because the mass of the nail and the rust is greater than the mass of the nail. c this is a chemical reaction and mass is conserved because the mass of the iron and oxygen around the nail is equal to the mass of iron plus the oxygen in the rust that formed. d this is a physical change because mass is not conserved since the nail and the rust have more mass than the nail before the rust formed.

Explanation:

A chemical reaction occurs when iron (Fe) combines with oxygen (O₂) to form rust (Fe₂O₃). According to the law of conservation of mass, mass is conserved in a chemical reaction. The oxygen from the air combines with the iron, increasing the mass of the nail - rust system, but the total mass of iron and oxygen before and after the reaction remains the same.

Answer:

C. This is a chemical reaction and mass is conserved because the mass of the iron and oxygen around the nail is equal to the mass of iron plus the oxygen in the rust that formed.