Exothermic and endothermic chemical reactions

I can identify whether a chemical reaction is exothermic or endothermic and explain how I know.

Exothermic and endothermic chemical reactions

I can identify whether a chemical reaction is exothermic or endothermic and explain how I know.

Slide deck

Lesson details

Key learning points

1. An exothermic chemical reaction causes an increase in temperature (of the surroundings).
2. An endothermic chemical reaction causes a decrease in temperature (of the surroundings).
3. An exothermic reaction transfers energy from the reactants to the surroundings.
4. An endothermic reaction transfers energy from the surroundings to the products.

Common misconception

The difference between the surroundings (where the reaction takes place, e.g. solution) and the environment (where the reaction mixture is, e.g. classroom). The existence of cold.

Use the separate terms of surroundings and environment throughout the lesson. Explain that thermal energy transfer only takes place from somewhere that is warmer and somewhere that is cooler.

Keywords

• Exothermic chemical reaction - is a type of reaction in which energy is transferred from the reactants to the surroundings, e.g. combustion.
• Endothermic chemical reaction - is a type of reaction in which energy from the surroundings is transferred to the products, e.g. photosynthesis.
• Dissipate - Thermal energy can dissipate which means it can be transferred to the environment and wasted.

Demonstrate the classic endothermic reaction between solid hydrated barium hydroxide and solid ammonium chloride, ensure this is practiced and risk assessed prior to the lesson.