Question

A piece of metal is dropped into a test tube of light-blue liquid. The piece of metal immediately starts fizzing and dissolving, and you can sense the heat radiating from the test tube even when your finger is an inch away.

2) A spoonful of salt is added to a beaker of water, and stirred. The salt dissolves completely in the water.

3) Two clear liquids in separate test tubes are mixed in a beaker. Within a minute, you observe water condensation on the beaker, and you can sense the cold radiating from the beaker even when your finger is an inch away.

4) In a dimly lit room, two clear liquids in separate test tubes are mixed in a beaker. Within a minute, you notice that the solution in the beaker is glowing.

5) You have two beakers filled with equal amounts of the same substance, a clear liquid. Beaker A is placed under a bright light, while beaker B is placed in the dark. When you examine the beakers after five minutes, a precipitate has formed in beaker A, while beaker B is unchanged.

6) A beaker filled with a clear liquid is placed under a UV lamp. When the lamp is turned on, the liquid glows orange. When the lamp is turned off, the liquid immediately stops glowing.

For each of the six situations, please determine if one or more (or none) of the four terms listed at the beginning of the assignment describes what is going on, and briefly defend your response.

exothermic, endothermic, exergonic, and endergonic,

Answer 1

1) For the first statement as in question, it is an example of exothermic reaction because it involves release of heat even if you are standing far away from the reaction. Therefore reaction for first statement is exothermic reaction.

2) Since to dissolve salt, we apply some energy for stirring. This apply of energy will dissolve the salt completely. Therefore it is endothernic reaction since you supply energy to it.

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