Sally is doing an experiment in chemistry class where she mixes two substances together. When the tow substances react, she notices that the beaker feels cold. What conclusion can Sally draw about this chemical reaction?
a
It is an endothermic reaction
b
The two substances did not react
c
She cannot draw conclusions based on this information
d
It is an exothermic reaction
a) It is an endothermic reaction
The correct conclusion Sally can draw about this chemical reaction is d) It is an exothermic reaction.
The correct answer is A: It is an endothermic reaction.
To arrive at this conclusion, Sally can make use of her observation that the beaker feels cold after the two substances react. This sensation of coldness indicates that heat is being absorbed from the surroundings during the reaction.
In general, an endothermic reaction is one in which energy is absorbed or taken in from the surroundings, resulting in a decrease in temperature. This conforms with Sally's observation of the cold beaker.
On the other hand, an exothermic reaction is one in which energy is released or given off to the surroundings, leading to an increase in temperature. If Sally had observed that the beaker felt hot after the reaction, she could have concluded it was an exothermic reaction.