Changes in Matter

Freezing

• Freezing is a chemical change that transforms a solid into a liquid.

• Freezing is a PHYSICAL CHANGE where a liquid turns into a solid, without altering its chemical composition.

• Freezing is a process that occurs only at high temperatures.

• Freezing is a method used to evaporate liquids.

frying an egg

• PHYSICAL CHANGE (same substance)

• CHEMICAL CHANGE (new substance)

• MECHANICAL CHANGE (no new substance)

• PHYSICAL REACTION (temporary change)

Heat in Endothermic Reactions

• Endothermic reactions release heat energy and the temperature increases.

• Endothermic reactions absorb heat energy and the temperature decreases.

• Endothermic reactions do not involve heat energy changes.

• Endothermic reactions absorb heat energy and the temperature remains constant.

Evaporation

• Evaporation is an example of a chemical change.

• Evaporation is an example of a physical change (phase change).

• Evaporation is an example of a biological change.

• Evaporation is an example of a nuclear change.

Explain why the reaction is exothermic.

• The temperature is INCREASING during the reaction

• The reaction absorbs heat from the surroundings

• The reaction requires energy input to proceed

• The temperature remains constant throughout the reaction

Digestion

• A physical change where food is mixed but not broken down.

• A chemical change where food is broken down into simpler substances in the body.

• A process that only occurs in the stomach without any chemical reactions.

• A method of storing food for later use.

Explosions

• Explosions are examples of PHYSICAL REACTIONS

• Explosions are examples of CHEMICAL REACTIONS

• Explosions are examples of BIOLOGICAL REACTIONS

• Explosions are examples of MECHANICAL REACTIONS

Define an exothermic reaction.

• An exothermic reaction absorbs heat, causing the temperature to decrease.

• An exothermic reaction releases heat, causing the temperature to increase.

• An exothermic reaction has no effect on temperature.

• An exothermic reaction requires heat to proceed.

breaking a stick

• PHYSICAL CHANGE (making it smaller)

• CHEMICAL CHANGE (altering its composition)

• PHYSICAL CHANGE (changing its color)

• CHEMICAL CHANGE (producing a new substance)

Temperature Change in Endothermic Reactions

• Endothermic reactions result in a temperature INCREASE in the surroundings.

• Endothermic reactions result in no temperature change in the surroundings.

• Endothermic reactions result in a temperature DECREASE in the surroundings.

• Endothermic reactions result in a temperature FLUCTUATION in the surroundings.