Question 13

Question

Question 13
 When an ice cube melts in your hand, it changes from a solid to a liquid.

H2O (s) → H2O (l)

This is an example of ________________ reaction, because heat is _____________ the system.

a
exothermic; leaving
 b
exothermic; entering
 c
endothermic; entering
 d
endothermic; leaving
Question 14
A fire is an example of ________________ reaction, because heat is _____________ the system.

a
exothermic; entering
 b
endothermic; leaving
 c
exothermic; leaving
 d
endothermic; entering
Watch the following video on reaction rates and answer the corresponding questions.

\ 
Question 15
The energy that is needed to start a chemical reaction is called:

a
start-up energy
 b
chemical reactions do not need energy to start
 c
activation energy
 d
exothermic energy
Question 16
Which of the following is NOT a way to speed up a chemical reaction? (Select all that apply)

a
decreasing the surface area of one of the reactants
 b
increasing the concentration of one of the reactants
 c
increasing the temperature of one of the reactants
 d
decreasing the temperature of one of the reactants

GPT-4o mini · Answer

Here are the answers to your questions:

Question 13: When an ice cube melts in your hand, it changes from a solid to a liquid:

Answer: c) endothermic; entering
Explanation: The melting of ice (H2O (s) → H2O (l)) requires heat to be absorbed from the surroundings (in this case, your hand), making it an endothermic reaction.

Question 14: A fire is an example of ________________ reaction, because heat is _____________ the system.

Answer: a) exothermic; entering
Explanation: A fire releases heat into the surroundings, which is characteristic of an exothermic reaction.

Question 15: The energy that is needed to start a chemical reaction is called:

Answer: c) activation energy
Explanation: Activation energy is the minimum energy required for a chemical reaction to take place.

Question 16: Which of the following is NOT a way to speed up a chemical reaction? (Select all that apply)

Answer: a) decreasing the surface area of one of the reactants
Answer: d) decreasing the temperature of one of the reactants
Explanation: Decreasing the surface area and decreasing the temperature would slow down a chemical reaction, while increasing concentration or temperature would speed it up.