Question

b. iron reacts with oxygen to form rust. unbalanced equation: fe + o₂ → fe₂o₃

1. balance the equation:
2. what type of reaction is this? (synthesis, decomposition, etc.)

part 5: apply the law of conservation of mass

1. in a closed system, 10 grams of hydrogen react with 80 grams of oxygen. how many grams of water are produced? answer: ____________ grams
2. why must a chemical equation be balanced?

part 6: mini - lab reflection (observation - based)
scenario: you mix two colorless solutions in a beaker. after a few seconds, the mixture turns cloudy and a yellow solid settles to the bottom.

1. what evidence suggests that a chemical reaction occurred?
2. what is the name for the solid that formed?

Explanation:

Step1: Balance the iron - oxygen reaction equation

We need to balance the number of atoms on both sides. The balanced equation is $4Fe + 3O_2
ightarrow2Fe_2O_3$.

Step2: Identify the type of reaction

The reaction $4Fe + 3O_2
ightarrow2Fe_2O_3$ is a synthesis reaction because two substances (iron and oxygen) combine to form a single product (iron(III) oxide).

Step3: Apply the Law of Conservation of Mass

The chemical equation for the reaction of hydrogen and oxygen to form water is $2H_2+O_2
ightarrow2H_2O$. According to the Law of Conservation of Mass, the total mass of reactants equals the total mass of products in a closed - system. So, if 10 grams of hydrogen react with 80 grams of oxygen, the mass of water produced is $10 + 80=90$ grams.

Step4: Explain why a chemical equation must be balanced

A chemical equation must be balanced to satisfy the Law of Conservation of Mass. This law states that matter is neither created nor destroyed in a chemical reaction, so the number of atoms of each element must be the same on both sides of the equation.

Step5: Determine evidence of a chemical reaction

The evidence that a chemical reaction occurred when two colorless solutions are mixed and the mixture turns cloudy and a yellow solid settles to the bottom is the formation of a precipitate (the yellow solid) and a change in the clarity of the solution (from clear to cloudy).

Step6: Name the solid that formed

The name for the solid that formed is a precipitate.

Answer:

1. $4Fe + 3O_2

ightarrow2Fe_2O_3$

1. Synthesis reaction
2. 90
3. To satisfy the Law of Conservation of Mass
4. Formation of a precipitate and change in clarity
5. Precipitate