Chemical reactions test

Answer 1

1. Define a chemical reaction and give an example.
- A chemical reaction is a process in which one or more substances are converted into new substances with different physical and chemical properties. Example: the reaction between hydrogen gas and oxygen gas to form water.

2. What are the four main types of chemical reactions?
- The four main types of chemical reactions are synthesis (combination), decomposition, single displacement, and double displacement.

3. What is a catalyst and how does it affect a chemical reaction?
- A catalyst is a substance that increases the rate of a chemical reaction without being consumed in the process. It works by lowering the activation energy required for the reaction to occur.

4. What is the difference between exothermic and endothermic reactions?
- An exothermic reaction releases heat to its surroundings, resulting in an increase in temperature. An endothermic reaction absorbs heat from its surroundings, resulting in a decrease in temperature.

5. How can you determine if a chemical reaction has occurred?
- Some signs that a chemical reaction has occurred include the formation of a precipitate, a change in color, the evolution of gas, or a change in temperature.

6. Balance the following chemical equation: Fe + O2 -> Fe2O3
- 4Fe + 3O2 -> 2Fe2O3

7. What is the Law of Conservation of Mass and how does it apply to chemical reactions?
- The Law of Conservation of Mass states that matter cannot be created or destroyed in a chemical reaction; it can only change form. This means that the total mass of reactants must equal the total mass of products in a chemical reaction.