Question

What is an aqueous solution? What is the difference between the solute and the solvent?

Short answer

An aqueous solution is any solution where water acts as the solvent. Solute is the substance that is dissolved (e.g., salt), while solvent is the substance that does the dissolving (e.g., water in an aqueous solution).

Step-by-step solution

Definition of Aqueous Solution

An aqueous solution is a solution where water is the solvent. In chemistry, a solution is a homogeneous mixture composed of two or more substances. In the case of an aqueous solution, the solvent is water, and the solute is the substance dissolved in the water.

Understanding the Solute

The solute is the substance that is being dissolved in a solution. It is present in a smaller amount compared to the solvent. For example, in a saltwater solution, salt is the solute.

Understanding the Solvent

The solvent is the substance that dissolves the solute. In an aqueous solution, the solvent is water. It is usually present in a larger amount than the solute. The solvent determines the state (solid, liquid, or gas) of the solution, and in an aqueous solution, water is the liquid phase.

Key concepts

Solute and Solvent

The terms solute and solvent are essential to understanding what happens when substances are mixed to form a solution. A solute is a substance that is dissolved in another substance. When making a cup of sugar water, for example, sugar is the solute. It's typically present in a smaller amount.

In contrast, the solvent is the substance that does the dissolving. It's often in a larger quantity than the solute. Water is known as the 'universal solvent' because it's capable of dissolving more substances than any other liquid. This capability is due to its polar nature. If we consider our earlier example, in sugar water, water acts as the solvent. It's important to grasp that the solvent determines the solution's state. In the case of an aqueous solution, while the solute can be solid, liquid, or gas before it's dissolved, the solvent (water) ensures the final solution is in liquid form.

• Solute: substance being dissolved (e.g., salt).
• Solvent: substance doing the dissolving (e.g., water).

Homogeneous Mixture

A homogeneous mixture is a type of mixture in which the composition is uniform throughout. This means that any given sample of the mixture will have the same properties and ratio of components as any other sample. The concept is closely related to solutions, such as those formed when substances are dissolved in water.

When a solute like salt dissolves in water, it spreads evenly at the molecular level. This distribution creates a consistent mixture - or a homogeneous mixture - where the salt is indistinguishable from the water to the naked eye. Such mixtures are also known as solutions. In chemistry, a solution doesn't refer to the problem-solving kind but rather to a homogeneous mixture like saltwater, where the solute is soluble in the solvent.

Characteristics of Homogeneous Mixtures

• Uniform composition.
• Components are not visibly distinct.
• Properties are consistent throughout the mixture.

Dissolving Substances in Water

The process of dissolving substances in water is fascinating and can be observed in everyday life, from a teaspoon of sugar in tea to salt in cooking water. This process is a physical change where a solute is incorporated into a solvent, in this case, water, to form a solution.

To dissolve a substance in water, the bonds between the water molecules and between the solute particles must be considered. Water molecules are polar, with a slightly positive side and a slightly negative side, which allows them to attract and separate ions or molecules of a solute. The solute particles diffuse throughout the water until they are evenly distributed, forming an aqueous solution.

Factors Affecting Dissolution

Several factors can influence how well and how quickly a substance dissolves in water:

• Temperature: Raising the temperature often increases solubility.
• Stirring: Stirring helps distribute solute particles more quickly.
• Particle Size: Smaller particles dissolve faster due to the larger surface area in contact with the solvent.
• Nature of the Solute: Some substances, like oil, do not dissolve in water due to differing polarity.