Volume and Pressure

[Emmet Asker]

I know we said that only gaseous reactions can cause a change in volume, but is there ever a situation where there is a change in volume from an aqueous reaction?

Additionally, how would the calculations change if we were to change the final volume ourselves in an experiment with an aqueous reaction?

[hiranya sundar 2D]

I think it's really hard to change the volume of a liquid using pressure because of how liquids work/move. However, by adding more liquid for non-dilute solutions, we could technically change the concentration of solvents enough to affect equilibrium.

[Nina Chessa 2A]

I don't think we will have to worry about this type of problem. For the purposes of the class I think it is safe to assume that only gases will be able to expand/compress.

[Angie Tan 2L]

When only aqueous is involved in the reaction, there won't be volume change since the amount of the substance stays the same and density of the same substance is always the same. However, if you start adding/removing the substance, then you would be working with an open system where the amount of matter changes and the equations we learned in class wouldn't be enough to calculate internal energy changes.

[Vishal Reddy Kunam]

I believe that in this class, we will only be focusing on the effects of gaseous reactions on volumes. Solids, liquids, and aqueous solutions will be omitted.

[Thomas_Lehman_2D]

An aqueous solution will not have a change in volume under pressure as when you compress a liquid, it does not change its volume.

[Caitlin Pan 1J]

For the scope of this class, only gases can change volume (expand/compress). Liquids (and solids) have a relatively defined volume that won't change significantly with pressure and therefore the change in such volume (if there is any) is negligible. At the moment, most of what we have learned is assuming a closed system, which means that it does not apply to the instance in which volume is physically altered by an exchange of matter between the system and its surroundings (by taking out or increasing volume of a liquid).