What is an aqueous solution? A) Pure water. B) Water dissolved in another solvent. C) A solute, or solutes, dissolved in water. D) A one molar solution. Or E) a weak solution.
The term aqueous solution is made up of two parts, aqueous and solution. Let’s start with the definition of a solution. A solution is a homogeneous mixture of a major component, the solvent, and one or more minor components, the solutes. In this context, homogenous means evenly distributed. Solutes in a solution are said to be dissolved in the solvent. Aqueous means of, or containing, water. The word aqueous is derived from aqua, the Latin for water. So, from this, you should be able to tell that an aqueous solution is a solution containing water.
But the question remains whether water is the solvent or a solute. For this question, you’ll simply have to recall that when a solution is described as aqueous, aqueous refers to the solvent. So an aqueous solution is a solution where the solvent is water. Now, let’s have a look at the options and see which one best applies.
Option A is pure water. But pure water is only water. Therefore, it is not a mixture. And therefore it’s not a solution and not a solution to this question. What about water dissolved in another solvent? In this case, as water is dissolved, it is a solute and not the solvent. Since aqueous solutions have water as the majority component, the solvent, this is an incorrect answer.
What about a solute or solutes dissolved in water? This describes a solution, a mixture of solutes and solvent, where water is the solvent. This is a good description of an aqueous solution and is therefore the correct answer. Just to be safe, I’m going to take a look at the other two options. The phrase, a one molar solution, does of course refer to a solution. But there’s no indication that water is the solvent. One molar refers to the concentration of the solute and doesn’t necessarily mean that the solvent is water. Therefore, this is not a correct answer.
Likewise, weak in a weak solution refers to concentration of the solute and not the identity of the solvent. Since the solvent could be something other than water, this is not a good description of an aqueous solution. And therefore it’s an incorrect answer. So what is an aqueous solution? A solute or solutes dissolved in water.