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
endothermic; entering
b
endothermic; leaving
c
exothermic; entering
d
exothermic; leaving
c) exothermic; entering
The correct answer is:
c) exothermic; entering
To determine the answer, we need to understand the concepts of endothermic and exothermic reactions.
An endothermic reaction is a reaction that absorbs heat from its surroundings. In this case, when the ice cube melts, it requires heat from the surroundings to break the hydrogen bonds between water molecules and turn the solid ice into liquid water.
On the other hand, an exothermic reaction releases heat into its surroundings. This occurs when new bonds are formed in the products, resulting in the release of energy.
In the given scenario, the ice cube is melting, which requires heat from the surroundings. Thus, this example represents an endothermic reaction.
Now, we can determine the correct choice based on the second part of the question - whether the heat is entering or leaving the system. Since the ice cube is absorbing heat from its surroundings to melt into liquid water, the heat is entering the system.
Combining these two pieces of information, the correct answer is:
a) endothermic; entering