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Which One Doesn't Belong? - Energy and Chemical Reactions - Questions 12 Help

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Chemical changes are always accompanied by energy changes. The energy level of reactant chemicals is different than the energy level of product chemicals. The chemicals, often regarded as the system, will acquire energy from the surroundings or release energy to the surroundings as the change from reactants to products take place. This causes a decrease or increase in the temperature of the surroundings.

There are three questions in this Question Group. Each question is very similar to one another. The question below is one of the questions.
 

Version 1:

One of these representations is not like the others. Which one doesn't belong?
 

Endothermic vs. Exothermic

Chemical reactions can be regarded as either endothermic reactions or exothermic reactions. The two terms describe the direction in which energy is transferred across the boundary between the system (reactant and product chemicals) and the surroundings (everything else in the universe). In an endothermic reaction, energy is transferred from the surroundings to the system of chemicals. This gain in energy by the system is required in order for the reaction to occur. In an exothermic reaction, energy is released by the system of chemicals to the surroundings. This loss of energy from the system occurs because the energy of products is less than the energy of reactants.

These concepts of endothermic and exothermic can be represented in a variety of ways. The graphic below communicates the connection between these terms and the variety of ways they are represented.








 

Get a Game Plan

Sometimes all you need is a good game plan - the proper approach. In this question, a good game plan would involve identifying each representation as being representative of either an endothermic reaction or an exothermic reaction. So use the graphic above and do the translation work for the four representations. When done, you should have three exothermic representations and one endothermic (or vice versa). Then you will be able to make your decision.