-Chemical Reaction:

A process where atoms rearrange to form new substances (e.g., burning wood turns it into ash and gases).

- Reactant:

A substance that starts a chemical reaction (e.g., wood and oxygen in a fire).

- Product:

A substance formed after a chemical reaction (e.g., ash and carbon dioxide from burning wood).

-Conservation of Matter:

The total mass of reactants equals the total mass of products; atoms are neither created nor destroyed.

- Exothermic Reaction:

A reaction that releases heat or light (e.g., burning a match).

- Endothermic Reaction:

A reaction that absorbs heat (e.g., photosynthesis).

- Activation Energy:

The energy needed to start a chemical reaction.

- Cellular Respiration:

A metabolic reaction in the body that breaks down food (glucose) with oxygen to release energy, producing carbon dioxide and water.

- Metabolic Reactions**:

Chemical reactions in living organisms that provide energy (e.g., digesting food).

1. What is a chemical reaction?

A process that rearranges atoms to form new substances

- Explanation: A chemical reaction changes the way atoms are bonded, creating new substances (e.g., rust forming on iron).

2. What is the anchoring phenomenon in the Chemical Reactions and Matter unit?**

How a match burns and produces light

- Explanation: The burning match is used to show how reactants (wood, oxygen) turn into products (ash, gases) and release energy.

3. What is formed that indicates a chemical reaction has occurred?

a gas or precipitate

- Explanation: Signs of a chemical reaction include gas bubbles, a solid (precipitate) forming, or color changes, not just physical changes like size or position.

4. What is conserved during a chemical reaction?

The total mass of the reactants and products

- Explanation: Atoms don’t disappear or appear; their total mass stays the same (conservation of matter).

5. What is a reactant?

A substance that undergoes a chemical change

- Explanation: Reactants are the starting materials that change during a reaction (e.g., baking soda in a vinegar reaction).

6. **What is the primary focus of the Chemical Reactions and Energy unit?

How chemical reactions release or absorb energy

- Explanation: This unit explores how reactions give off or take in energy, like heat or light.

7. What type of energy is released or absorbed during a chemical reaction?

Thermal or light energy

- Explanation: Chemical reactions often release or absorb heat (thermal energy) or light (e.g., a glowing fire).

8. What makes a reaction exothermic

It releases heat to the surroundings

- Explanation: Exothermic reactions, like burning wood, feel hot because they release heat.

9. What is an example of an endothermic reaction?

Photosynthesis

- Explanation: Photosynthesis takes in energy from sunlight to make food, making it endothermic.

10. What does a model of energy transfer show?

How energy moves between the system and surroundings

- Explanation: Models show how energy flows, like heat leaving a reaction to warm the air around it.

11. What is the anchoring phenomenon in the Metabolic Reactions unit?**

How food provides energy for the body

- Explanation: This unit focuses on how food’s chemical energy fuels body activities through reactions.

12. What is the primary source of energy for metabolic reactions in the body?**

Chemical energy stored in food

- Explanation: Food contains energy that the body uses through metabolic reactions like cellular respiration.

13. Which process breaks down food to release energy?

Cellular respiration

- Explanation: Cellular respiration breaks down glucose with oxygen to release energy for the body.

14. **What are the main products of cellular respiration?**

Carbon dioxide and water

- **Explanation**: Cellular respiration uses glucose and oxygen, producing carbon dioxide and water as waste.

15. **What role does oxygen play in cellular respiration?**

It is a reactant that helps break down glucose

- **Explanation**: Oxygen is needed to break down food molecules to release energy.

16. **What is a product of a chemical reaction?**

A substance formed as a result of the reaction

- **Explanation**: Products are the new substances made after a reaction (e.g., water from burning hydrogen).

17. **What happens to the atoms in a chemical reaction?**

They are rearranged to form new substances

- **Explanation**: Atoms don’t vanish or appear; they just form new combinations.

18. **What is activation energy?**

The energy needed to start a chemical reaction

- **Explanation**: Activation energy is like the “push” needed to get a reaction going (e.g., striking a match).

19. **Which of the following is a metabolic reaction in the body?**

Digesting food to produce energy

- **Explanation**: Metabolic reactions, like digestion, happen in living things to provide energy.

20. **What is the purpose of modeling in the Chemical Reactions and Matter unit?**

To explain how atoms rearrange during a reaction

- **Explanation**: Models help show how atoms in reactants rearrange to form products.

Open-Response Questions: Tips and Example Answers

Question 21: Explain how the Chemical Reactions and Matter unit uses the phenomenon of a burning match to help students understand chemical reactions. Include at least two specific concepts (e.g., reactants, products, conservation of matter) and how they relate to the phenomenon.

- **Tips**:

- Start by describing the burning match and why it’s a good example of a chemical reaction (it changes wood into new substances).

- Pick two concepts (e.g., reactants/products, conservation of matter) and explain them clearly.

- Connect each concept to the match: What are the reactants? What are the products? How does mass stay the same?

- Use simple language and examples to show understanding.

- **Example Answer**:

The burning match helps us understand chemical reactions because it shows how things change into new stuff. One concept is reactants and products. The reactants are the wood on the match and oxygen in the air. When the match burns, they turn into products like ash, smoke, and carbon dioxide gas. This shows a chemical reaction because new substances are made. Another concept is conservation of matter. The atoms in the wood and oxygen don’t disappear when the match burns; they just rearrange to form the products. Even though the match looks smaller, the total mass of the reactants equals the mass of the products, like the gases that go into the air.

Open-Response Questions: Tips and Example Answers

Question 22: Describe an experiment from the Metabolic Reactions unit that demonstrates how food provides energy for the body. Include the setup, observations, and what the experiment reveals about metabolic reactions.

- Tips:

- Describe a clear experiment, like burning food in a calorimeter, and explain the setup (e.g., equipment used).

- Mention specific observations, like temperature changes, to show what happened.

- Explain how the experiment connects to metabolic reactions (e.g., how burning food is similar to cellular respiration).

- Keep the explanation simple but include enough detail to show the link to energy.

Example Answer:

In the Metabolic Reactions unit, we did an experiment with a calorimeter to show how food provides energy. We set it up by placing a cheese puff under a can filled with water and lighting the cheese puff on fire. We measured the water’s temperature before and after burning with a thermometer. We observed that the water’s temperature went up, like from 20°C to 25°C, because the burning cheese puff released heat. This experiment shows that food has chemical energy, just like how our bodies use metabolic reactions like cellular respiration to break down food with oxygen. In our bodies, this energy helps us move and grow, similar to how the heat warmed the water.