Iron combines with oxygen to form rust. Given the chemical reaction, how many grams of rust would be produced if 3 grams of reactants were consumed? A) 0 grams B) 1 gram C) 3 grams D) 7 grams

To answer this question, we need to consider the law of conservation of mass, which states that in a closed system, matter is neither created nor destroyed, but it can change forms. According to this law, the mass of the reactants in a chemical reaction must equal the mass of the products.

When iron (Fe) combines with oxygen (O2) to form rust, which is iron oxide (Fe2O3), the total mass of iron and oxygen before the reaction (reactants) will be equal to the mass of rust formed (product) after the reaction, provided the reaction goes to completion and all of the reactants are used up to form the product without any losses.

Given that 3 grams of reactants are consumed in the reaction to form rust, and assuming that all of that mass goes into forming rust without any being lost, the mass of the rust produced will also be 3 grams.

So, the correct answer is C) 3 grams.

Extra: It is important for students to understand that the law of conservation of mass is a fundamental concept in chemistry. This principle applies to all chemical reactions. In a balanced chemical equation, the number of atoms of each element is the same on both sides of the equation, reflecting this law.

In our example, the balanced equation for the formation of iron oxide (rust) might look something like this:

4Fe + 3O2 → 2Fe2O3