Endothermic and Exothermic

Endothermic and Exothermic

What are Endothermic and Exothermic?

• "Thermic" refers to the transfer of thermal energy.

• The outflow of thermal energy is what we feel as heat.

• When thermal energy is being pulled from our bodies we feel that as cold.

Endo vs Exo

• Endo means something is moving toward or into a substance or object.

• Exo means that something is moving out

• Endothermic means the thermal energy is being pulled into the object or substance, so it feels cold to us.

• Exothermic means thermal energy is being released from the object or substance, so it feels hot to us.

Multiple Choice

What type of chemical reaction absorbs energy and requires energy for the reaction to occur?

• Endothermic

• Exotermic

• Exothermic

• Endotermic

Multiple Choice

What term is given to a reaction which transfers heat energy to the surroundings?

• Endothermic

• Reversible

• Exothermic

• Exotermic

Why do I care?

• If a chemical reaction releases more energy than it takes in, it is exothermic. We use these types of reactions all of the time for our benefit.

• Example: Gasoline and additives are very exothermic when they burn. We use this energy to push large hunks of metal down the road.

• Example: If you have ever cooked over a flame or eaten bbq, the reason it was able to be cooked is the exothermic reaction of propane burning.

Why do I care? Continued

• Endothermic reactions are one way that organism store energy for later use.

• Your cells use a molecule called ATP to store energy. It is a very endothermic reaction that takes in energy in order to store it so the cell can used it when it wants.

• Sugar is another example of an endothermic reaction. Plants take in the energy of the sun to form a new substance, sugar, to store energy for a longer time than ATP can.

Multiple Choice

____ reactions usually feel cold.

• endothermic

• exothermic

Multiple Choice

In an endothermic reaction, energy is _________.

• absorbed

• released

Multiple Choice

_____ reactions usually feel hot!

• endothermic

• exothermic

Multiple Choice

When calcium reacts with water, the temperature changes from 18°C to 39°C. Which statement is correct?

• The solution at the end is acidic

• The reaction is reversible

• The reaction is exothermic

• The reaction is endothermic

Multiple Choice

When barium hydroxide and ammonium chloride react, the temperature of the mixture decreases. What kind of reaction is this?

• Endothermic

• Decomposition

• Exothermic

• Indothermic

Don't forget the five ways you can physically change a substance or object

• Change of Shape

• Change of Temperature

• Change of Texture

• Change of State of Matter

• Change of Color

Also remember: 5 Evidences of a chemical change

• Unexpected Change in Color

• Unexpected Change in Temp (Endothermic or Exothermic)

• Precipitate forms

• Bubbles (Gas is released)

• Combustion/burning

Multiple Choice

Evaporating Water

• Physical Change

• Chemical Change

Multiple Choice

Slicing Bread

• Physical Change

• Chemical Change

Multiple Choice

Cooking Pancakes

• Physical Change

• Chemical Change

Multiple Choice

Rotting banana

• Physical Change

• Chemical Change

Multiple Choice

Blowing up a balloon

• Physical Change

• Chemical Change

Multiple Choice

Lighting a Match

• Physical Change

• Chemical Change

Multiple Choice

• Physical Change
• Chemical Change

Multiple Choice

• Physical Change
• Chemical Change

Multiple Choice

What is the evidence of the chemical change seen here?

• Color change
• Light produced
• state change
• mixture

Multiple Choice

What is a physical property of this table? 

• Brown
• Flammable
• Reactive to Acid

Multiple Choice

A chemical reaction accompanied by the releasing of heat. 

• Endothermic
• Exothermic
• Mesothermic
• Misothermic

Multiple Choice

Evidence of a physical change.

• New substance
• Shape Change
• Light produced
• Gas released.

Multiple Choice

Which of the following is a physical change?

• precipitate
• color change
• change in temperature (colder, hotter)
• gas/bubbles

Multiple Choice

Which evidence demonstrates that a chemical change has occurred.

• water level rises
• water becomes cloudy
• gas is produced (bubbles)
• tablet dissolves

Multiple Choice

Which of the following is NOT evidence that that a chemical reaction has occurred?

• produces light/heat
• production of a gas
• formation of a precipitate
• melting

Multiple Choice

Evidence of a chemical reactions is anything that shows - 

• a new substance has formed
• a solid dissolved in a liquid
• interaction between 2 gases
• a change in the state of matter

Multiple Choice

Which of the following is an example that includes evidence of a chemical reaction?

• A sample of zinc is placed in water and it settles to the bottom
• A solid block of ice is heated and it completely melts into a liquid. 
• Sugar that is burned gives off an odor and turns brown and then black.
• A tomato is placed into a blender and chopped up into smaller pieces.

Multiple Choice

A student places a piece of a potato into a container of hydrogen peroxide. One observation the student makes is that bubbles form around the potato. The presence of bubbles might indicate the formation of a new substance because bubbles - 

• could show that a gas is forming
• always rise to the top of a liquid. 
• are almost always perfectly spherical.
• usually burst after a few minutes.

Multiple Choice

A student mixes two clear liquids together. After a few minutes, a white powdery solid can be seen settling on the bottom of the test tube. Which of the following is a conclusion that the student can draw based on these observations? The two clear liquids-

• were pure substances before they were mixed

• are toxic and should be handled with extreme caution

• have gone through a chemical change in which a new substance called a precipitate was produced

• have been stored too long and are no longer good

Multiple Choice

• Physical Change
• Chemical Change

Multiple Choice

• Physical Change
• Chemical Change