States of Matter

[Jessica Helfond 2F]

Can someone explain to me what an aqueous solution is? And why do we need to include the state of matter when we write and balance chemical reactions?

[Neil Hsu 2A]

Aqueous means that something is dissolved in water. So something like NaOH(aq) would mean an NaOH solution with the solvent being water. Including states of matter when writing chemical equations provides a reference for how the reactants react with one another to form the products, kind of like an added visual (there's probably better reasoning out there).

[Destiny_Ryales_3J]

To the best my knowledge an aqueous solution just means that something is in a state where it was dissolved in water. For example salt dissolved in water is a chemical reaction that produces an aqueous solution.

[Pipiena Malafu 3J]

An aqueous solution is when something is able to be dissolved by water. We need to include the state of matter when writing and balancing chemical reactions as it allows us to determine the solubility of some chemical reactions.

[Laura Gong 3H]

To answer the second part of your question with respect to (aq), knowing whether or not a substance is aqueous in water will also tell you whether or not the compound dissociates, or separates into ions when dissolved in water. This can be important for when you're writing net ionic equations and only want to know which ions react with each other.

For example, in this precipitation reaction:
AgNO3 (aq)+ NaCl(aq) --> AgCl(s) +NaNO3(aq)

Complete chemical equation would be:
Ag+(aq)+NO3-(aq)+Na+(aq)+Cl-(aq)-->AgCl(s)+Na+(aq)+NO3-(aq).

And since Na+ and NO3- are spectator ions and can be "cancelled" out on both sides of the equation.

Net ionic equation:
Ag+(aq)+Cl-(aq)-->AgCl(s)

But aside from knowing whether or not a substance is aqueous in water or not, knowing the states of matter can be important in knowing the entropy of a reaction. Like say if you went from a liquid reactant to gas products, the entropy here would be positive, it's increasing disorder.

[Olivia Young 1A]

As previously mentioned, aqueous solutions are solutions such that the solvent is water. In solutions, there is a solvent and a solute, and the solvent is the dominant substance. Therefore, in aqueous solutions, the main component of the mixture is water and the compound is dissolved in water. Aqueous solutions are also very common, as opposed to nonaqueous solutions. In response to your second question, including states of matter when balancing chemical equations is vital because it provides us with as much information as possible in order to develop a net ionic equation. When splitting up a balanced equation into its total ionic equation, you must separate the aqueous solutions into their appropriate ions. If the same ions are on both sides and are both aqueous, then they are considered spectator ions and are removed from the equation to achieve the net ionic equation. Therefore, to reach the net ionic equation, knowing which components of the balanced equations are aqueous is necessary.

[Adam Vuilleumier 2K]

I've heard of other states of matter like plasma and Bose-Einstein condensates. Will we be covering how to handle those in this class? Is there any difference in balancing chemical equations with plasmas, etc. in them? Are there even any chemical reactions that involve plasmas?

[Kelsey Warren 1I]

Addressing the second part of your question, including the state of matter when writing and balancing equations has been very helpful for me in that I'm able to picture conducting the reaction in a lab, which we obviously aren't dealing with yet but we will in the future! It's also helpful when identifying the type of reaction that's taking place (ex. combustion, titration, etc.).

[deepto_mizan1H]

Since aqueous solutions have been discussed already, the most important thing about keeping track of states of matter during balancing equations is to get familiar with certain reaction patterns and probable products that may be formed. For combustion (for example) knowing the fact O2 gas is a fuel for combustion can be helpful to remember its relation to ultimately forming water vapor and CO2 gas. After lots of equations it'll become familiar how common compounds interact in presence of others and additionally how to expect the flow of a chemical reaction to go, because you know which state each part is in, and how it will most likely recombine to form something common.

[Nicole Jakiel 4F]

To add onto the first question, do we need to write the states of matter every time we balance a chemical reaction?

[Venya Vaddi 1L]

I asked my TA this question in discussion today and he said for this first test we do not need to worry about writing the states of matter in a balanced equation; it is something we will go over later.

[michelle]

Aqueous solution is the solution that the solvent is water. I actually think the chemical equations are designed to show the process of the experiments. To better represent the process, the states of reactant can help clarify the experiment.