8.2 Endothermic

​Success Criteria

• ​I can list some chemical reactions that are endothermic.

• I can explain the difference between an endothermic reaction and an endothermic process.

• I can carry out an investigation to distinguish between exothermic and endothermic reactions and processes.

• I can describe some uses of exothermic and endothermic reactions and processes.

Individual Goal: 90 to 95 % mastery/ accuracy




Class Goal: 95 % mastery level/accuracy

Challenge

Multiple Choice

What happens during an endothermic reaction?

• Thermal energy is released into the surroundings

• Thermal energy is absorbed and stored in chemical bonds

• The temperature of the surroundings increases

• New chemical bonds are not formed

Multiple Choice

Which of the following is an example of an endothermic reaction?

• Burning wood

• Mixing sodium hydrogencarbonate and citric acid

• Freezing water

• Condensation of water vapor

Multiple Choice

What is the word equation for the reaction between sodium hydrogencarbonate and citric acid?

• Sodium hydrogencarbonate + water → sodium hydroxide + carbon dioxide

• Sodium chloride + citric acid → sodium citrate + water

• Sodium hydrogencarbonate → sodium carbonate + carbon dioxide + water

• Sodium hydrogencarbonate + citric acid → sodium citrate + water + carbon dioxide

Dropdown

Complete the word equation between citric acid and sodium hydrogencarbonate



​

Select answer

+ ​

Select answer

---> ​ sodium citrate + ​ water + ​ ​

Select answer

Multiple Choice

Why does the test tube feel cooler when sodium hydrogencarbonate reacts with citric acid?

• Thermal energy is released into the surroundings

• The reaction absorbs thermal energy from the surroundings

• The test tube is made of insulating material

• Carbon dioxide gas is released

Multiple Choice

What happens when potassium chloride is dissolved in water?

• A chemical reaction takes place

• The solution releases heat into the surroundings

• Thermal energy is absorbed, making the beaker feel cold

• A solid precipitate is formed

Multiple Choice

Why is dissolving potassium chloride in water considered an endothermic process?

• It produces new substances

• It releases heat into the surroundings

• It absorbs thermal energy from the surroundings, causing a temperature drop

• It creates a solid from the liquid

Multiple Choice

In the process of dissolving potassium chloride in water, which statement is true?

• Potassium chloride is the solvent

• Water is the solute

• Potassium chloride is the solute and water is the solvent

• A chemical reaction occurs

Multiple Choice

What is the main difference between an endothermic reaction and an endothermic process?

• A process releases energy, while a reaction absorbs energy

• There is no difference between them

• A reaction absorbs energy, while a process does not

• A reaction involves new substances forming, while a process does not

Multiple Choice

Which statement best describes why dissolving potassium chloride in water is an endothermic process and not an endothermic reaction?

• A new substance is formed with different properties.

• The reaction creates a gas and changes the chemical structure.

• The potassium chloride only dissolves but remains the same substance.

• The process cannot be reversed.

Multiple Choice

What is true about the substances involved in an endothermic process like ice melting?

• The original substance changes into a completely new product.

• The process is irreversible and forms a new compound.

• The substance absorbs heat but remains chemically the same.

• A chemical reaction occurs, producing a different material.

Multiple Choice

When ice melts, what happens to the water molecules?

• They change into a new substance.

• They gain energy and change state, but no new product is formed.

• They react with air to form a different compound.

• They lose energy and become a solid

Multiple Choice

Which of the following statements is true about an endothermic process?

• It always creates a new chemical substance.

• It only involves a physical change, not a chemical one.

• It results in the formation of a new compound.

• It produces heat and light as a product.

Multiple Choice

Why does the beaker feel cold when potassium chloride dissolves in water, but no new substance is formed?

• The substance absorbs heat, but the chemical composition remains the same.

• A new product is formed, releasing cold air.

• The reaction removes particles from the solution.

• The water and potassium chloride react to form a gas.

Open Ended

Using your understanding about exothermic reaction, explain how does a self-heating can work?

​Using ENDOTHERMIC REACTIONS

​Ice Pack Usage

• Used to reduce swelling and cool injured areas.

• Stored in a fridge or freezer until needed.

• When applied to an injury, heat transfers from the body to the ice pack, causing it to melt.

• This is an endothermic process (not a reaction) because no new substances are formed.

• Can be refrozen and reused.

​Using ENDOTHERMIC REACTIONS

• Instant Ice Packs (Chemical Ice Packs)

  • Do not require a fridge or freezer.

  • Contain two compartments with different substances (e.g., ammonium nitrate and water).

  • When activated (by breaking a compartment), ammonium nitrate dissolves in water.

  • This is an endothermic process, absorbing heat and causing a temperature drop.

  • Useful for emergencies where refrigeration is unavailable.

Multiple Choice

Why are ice packs used on injuries?

• To increase blood flow to the injured area

• To absorb heat and reduce swelling

• To warm the injured area

• To speed up the chemical reaction in the body

Multiple Choice

What type of process occurs when an ice pack absorbs heat and melts?

• Exothermic process

• Endothermic process

• Chemical reaction

• Condensation
  

Multiple Choice

Why is the melting of an ice pack considered an endothermic process and not an endothermic reaction?

• Because new substances are formed

• Because it requires heat but does not create a new substance

• Because it releases heat instead of absorbing it

• Because it produces light energy

Multiple Choice

What makes instant (chemical) ice packs different from regular ice packs?

• They do not need to be stored in a freezer.

• They release heat instead of absorbing it.

• They contain a heating element.

• They are reusable like regular ice packs.

Multiple Choice

What happens when the compartment inside an instant ice pack is broken?

• The substances inside react and release heat.

• The substances mix, undergo an endothermic process, and lower the temperature.

• The pack heats up to reduce pain.

• The substances form a new solid product.

Multiple Choice

Which two substances are commonly found in instant ice packs?

• Sodium chloride and water

• Ammonium nitrate and water

• Carbon dioxide and water

• Oxygen and nitrogen

​Simulation

​Explore more about hot pack and/or cold pack by using the simulation below.

How do hot packs and cold packs change temperature?


Complete the worksheet provided by your teacher and submit once done.


Note: exclude question numbers 2 and 3.

Categorize

Options (14)

releases thermal energy

absorbs thermal energy

combustion of fuels

explosion of fireworks

burning of wood

photosynthesis

melting ice

feels colder

feels hot or warm

gives out energy

takes in energy

stores chemical energy in the chemical bonds

lower temperature

higher temperature

Organize these options into the right categories

Exothermic

Endothermic

​Again, remember that...

​Exothermic and endothermic can either be a reaction or a process.

Exothermic releases/gives out energy, and endothermic absorbs energy from the surrounding.

Both the reaction and process result to the increase of temperature (exothermic) and decrese of temperature (endothermic).

The main difference between a reaction and a process is that a reaction creates new products, while a process does not make new products.

Multiple Choice

Which of the following statements is correct about exothermic and endothermic reactions and processes?

• Exothermic reactions and processes absorb energy, while endothermic reactions and processes release energy.

• Exothermic and endothermic changes can only occur in reactions, not processes.

• Exothermic reactions and processes increase temperature by releasing energy, while endothermic reactions and processes decrease temperature by absorbing energy.

• The main difference between a reaction and a process is that both create new products.

Categorize

Options (2)

makes new products

does not make new product

Organize these options into the right categories

Difference between a reaction and process (endothermic and exothermic)

Reaction

Process

Open Ended

Using the concept of endothermic process, explain why ice melting is an example of endothermic process and not an endothermic reaction.

​Success Criteria

• ​I can list some chemical reactions that are endothermic.

• I can explain the difference between an endothermic reaction and an endothermic process.

• I can carry out an investigation to distinguish between exothermic and endothermic reactions and processes.

• I can describe some uses of exothermic and endothermic reactions and processes.

Homework

Science workbook exercises:

7.1 Exothermic
7.2 Endothermic