Exo and Endothermic Rxn Grade 8

What type of reaction occurs in a hand warmer

• exothermic
• endothermic

Baking bread and cooking an egg are examples of....?

• Endothermic processes
• Exothermic processess
• None of these 

Have you ever eaten sherbet sweets candy? They fizz in your mouth and your tongue feels cold. Why do you think that is?

• It is an exothermic reaction
• It is an endothermic reaction
• It is made of ice
• It is dissolving your mouth

A student mixed two chemicals to allow them to react. The temperature before the reaction was 25 ° C. The temperature after the reaction was 18° C. Which of the following is true? 

• The temperature changed 
• It is an endothermic reaction
• It is an exothermic reaction 
• Two of the answers are correct 

After you mix two substances together, a new substance forms.  This is an example of:
 

•  Physical Change
•  Chemical Change

A lizard egg needs a temperature of 26-30 ° C to hatch properly. You place it next to a pouch of water which is 22 °C. What type of chemical do you need for the egg? 

• Calcium chloride because it will be endothermic.
• Calcium chloride because it will be exothermic. 
• Citric acid because it will be exothermic. 
• Citric acid because it will be endothermic. 

For the cold pack shown left, the temperature on the outside surface has dropped considerably from its initial temperature of 25 °C. Which of the following provides the best explanation for this temperature decrease?

• The cold pack is releasing cold to the surroundings.

• Ice is beginning to form on the outside of the bag, lowering its temperature.

• Energy is traveling out of the bag into the surroundings, making the bag colder.

• The thermometer is measuring the temperature of the surroundings, which is losing energy.

In the picture left, the green spheres represent particles of solute that have been added to water. Bonds between the solute particles are indicated by orange lines. When this substance dissolves in water, what happens to the bonds between these particles?

• They are broken, releasing energy in the process.

• They are strengthened, since more of them will form.

• As they absorb energy, they are broken.

• They are unaffected.

The calorimeter pictured below shows the final temperature after calcium chloride was added to water. (The initial temperature was 25 °C.) Which of the following best describes what occurred within the calorimeter?

• Only bond forming occurred.

• The bonds that formed were for the most part stronger than the bonds that were broken.

• More energy was absorbed in breaking bonds than was released when new bonds form

• As the powder dissolved, the breaking of bonds released energy.

In an exothermic reaction, heat is ...

• taken in

• given out