Endothermic vs Exothermic Reactions

Endothermic vs Exothermic Reactions

• Candle burning - gives out heat and light energy

• Battery - gives out electrical energy

• Firework - gives out light, heat, and sound

Some reactions give out energy:

• cooking an egg - takes heat from a source (stove)

• Photosynthesis - takes in energy from the sun to make glucose and oxygen

• Instant ice packs - absorbs heat from surroundings (why pack becomes cold)

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Some chemical reactions store (take in) energy:

• Reactions that take heat from in outside source

• Endo - bring INSIDE

• Baking cake - cake takes heat from the oven

Endothermic Reactions

• Reactions that give out heat

• Exo - heat EXITING

• Combustion - when things are on fire, you feel heat being released

Exothermic Reactions

Endothermic and Exothermic

• Combustion - reaction between fuel and oxygen that produces light and heat energy

• Cars run on combustion - engine burns fuel

• Lighting a match - striking the match, the chemicals stored on the head of the match begin to burn

Exothermic and Combustion

Endothermic Reactions

• Harder to identify than Exothermic because they don't produce energy

• Require heat to be added in order to occur

• Some absorb heat from the environment, which then makes the surrounding area feel colder (heat moves from hot to cold)

Open Ended

How could you test for an endothermic reaction and tell that one has occurred?

Categorize

Options (7)

melting ice

cooking an egg

burning wood

fireworks exploding

mixing vinegar and baking soda

freezing water

combustion of gasoline

Categorize as either an endothermic or exothermic reaction.

Endothermic Reaction

Exothermic Reaction

Open Ended

Is photosynthesis an endothermic or an exothermic reaction? EXPLAIN your answer.

Categorize

Options (5)

B

C

A

D

E

Categorize the reactions as either endothermic or exothermic.

Endothermic

Exothermic

Heating vs Cooling

• Temperature change from a reaction can change the temperature of the surrounding area (remember, heat moves)

• Energy absorbed during an endothermic reaction can be used to cool the surrounding area

  • example: instant ice pack (heat goes into the ice pack, ice pack feels cold)

• Energy released during an exothermic reaction can be used to heat the surrounding area

  • example: a hand warmer (chemicals in warmer produce heat)

Multiple Choice

Which metal chloride would be the best to use in a hand warmer?

• calcium chloride

• magnesium chloride

• strontium chloride

• lithium chloride

Open Ended

How does changing the mass of the reactant affect the temperature change?