Energy changes
14 review questions with answers for Energy changes. Read them here, or play the set as a class game on the projector. Free to host, and students join with a code.
Reaction that gives out heat to the surroundings?
- Endothermic
- ExothermicRight answer
- Isothermal
- Thermal
What this set covers
Heat flow in chemical reactions, from exothermic and endothermic changes to bond breaking and bond making. Reaction profiles, activation energy, calculating an overall energy change, and heating water in a calorimetry experiment are all included.
- Common mix-up
- Students often think breaking bonds releases energy, but breaking bonds absorbs energy and making bonds releases it, so the overall sign depends on which side is larger.
- Review tip
- Draw both reaction profiles, label the reactants, products and activation energy, then use the 500 kJ and 700 kJ example to check your sign.
All 14 questions and answers
Reaction that gives out heat to the surroundings?
Answer: Exothermic
Reaction that takes in heat from the surroundings?
Answer: Endothermic
Example of a reaction that gives out heat?
Answer: Combustion
In an endothermic reaction, the temperature of the surroundings…?
Answer: Falls
Breaking chemical bonds…?
Answer: Absorbs energy
Making chemical bonds…?
Answer: Releases energy
Energy needed to start a reaction?
Answer: Activation energy
On a reaction profile for an exothermic reaction, the products are…?
Answer: Lower than the reactants
Overall energy change if breaking bonds takes 500 kJ and making bonds gives 700 kJ?
Answer: −200 kJ
Energy to heat 100 g of water by 5 °C (c = 4.2 J g⁻¹ °C⁻¹)?
Answer: 2100 J
Container used to reduce heat loss in a simple calorimetry experiment?
Answer: Polystyrene cup
Measured to compare how much energy fuels release when heating water?
Answer: Temperature rise
Everyday product that uses an exothermic reaction?
Answer: Hand warmer
Unit of energy?
Answer: Joule
Play it as a class game
Play this set opens it in splycr, where you can host it for your class straight away. Hosting needs no account: put the room code on the projector, and students join from a phone with the code and their first name. Each question plays as multiple choice, and the three wrong options were written for that question.