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Picturing Reactions

APCHEM-4NXJYS

Consider the two sets of molecules in the figure below. Each represents a sample of a diatomic element, where the red spheres represent element ${ A }_{ 2 }(g)$, and the blue spheres are molecules of element ${ B }_{ 2 }(g)$.

Created for Albert.io. Copyright 2016. All rights reserved.

If the two gaseous elements react according to the equation:

$${ A }_{ 2 }(g)+{ B }_{ 2 }(g)\rightarrow { A }_{ 2 }{ B }_{ 2 }(g)$$

...which of the following BEST describes the result of the reaction?

Assume the reaction takes place at constant pressure.

A

Four molecules of ${ A }_{ 2 }{ B }_{ 2 }(g)$ will form; the volume will decrease by less than 50%.

B

Four molecules of ${ A }_{ 2 }{ B }_{ 2 }(g)$ will form; the volume will decrease by 50%.

C

Four molecules of ${ A }_{ 2 }{ B }_{ 2 }(g)$ will form; the volume will remain the same.

D

Five molecules of ${ A }_{ 2 }{ B }_{ 2 }(g)$ will form; the volume will remain the same.