What is the main difference between an endothermic and an exothermic reaction, in terms of energy?

Endothermic reactions absorb energy, while exothermic reactions release energy.

In photosynthesis, is energy absorbed or released? What form does this energy take?

Energy is absorbed in the form of sunlight.

Explain, in terms of bond breaking and bond forming, why some reactions release energy and others absorb energy.

Breaking bonds requires energy, while forming bonds releases energy. If more energy is released than absorbed, the reaction is exothermic. If more energy is absorbed than released, the reaction is endothermic.

Describe how a cold pack works in terms of energy transfer between the system and the surroundings.

A cold pack contains a reaction that absorbs energy from its surroundings, causing the surroundings (like your hand) to cool down. This is an endothermic process.

Energy In Chemical Reactions Lesson Plan for Grade 7th Grade

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Learning Objective

I can describe how energy is either released or absorbed during a chemical reaction.

1
In photosynthesis, carbon dioxide reacts with water to produce glucose and oxygen, and this reaction absorbs energy from sunlight.
2
Endothermic reactions absorb energy, while exothermic reactions release energy into the surroundings.
3
The law of conservation of energy states that energy is not created or destroyed, but only transferred from one entity to another.

Energy in Chemical Reactions

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Learning Objective

Warm-Up Video

Key Concepts

Practice Questions

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