Which of the following processes is exothermic?
a.rolling a ball up a hill
b.boiling water in a beaker to make steam
c.allowing meat to thaw after taking it out of the freezer
d.reacting hydrogen and oxygen gases to make water
e.a popsicle melting on a warm summer day
i got d.
Energy going in is endothermic.
Energy going out is exothermic.
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To determine which of the processes is exothermic, we need to understand what exothermic means. Exothermic processes are those that release energy in the form of heat to the surroundings.
Let's analyze each process to determine if it is exothermic:
a. Rolling a ball up a hill: This process requires energy input to overcome gravitational potential energy. It is an endothermic process because energy is absorbed, rather than released. Therefore, it is not exothermic.
b. Boiling water in a beaker to make steam: This process involves heating the water to its boiling point, where it undergoes a phase change from liquid to gas. The phase change is an endothermic process because energy is absorbed to break the intermolecular bonds. So, boiling water to make steam is not exothermic.
c. Allowing meat to thaw after taking it out of the freezer: Thawing meat involves the absorption of heat energy from the surroundings to raise its temperature. This process, therefore, is an endothermic process and not exothermic.
d. Reacting hydrogen and oxygen gases to make water: This process is known as a combustion reaction and is highly exothermic. When hydrogen and oxygen combine, they release a large amount of heat energy. So, this process is exothermic.
e. A popsicle melting on a warm summer day: Melting is a phase change from solid to liquid, which requires energy input to break intermolecular bonds. Therefore, it is an endothermic process and not exothermic.
So, out of the given processes, the only one that is exothermic is d. Reacting hydrogen and oxygen gases to make water.