What is a Solute?
A solute is a substance that is dissolved in a solvent to form a solution. In an unsaturated solution, the concentration of solute is much lower than that of the concentration of solvent. Let’s take an example of a solution from day-to-day life—a solution of salt and water. In the given solution, salt acts as a solute while water acts as a solvent. So salt and water in the given example are solute and solvent examples, respectively. Here, we will study what is meant by solute, solute, and solvent examples in detail.
Solute and Solvent Definitions
To define solute and solvent, let us go through the following explanation.
A homogeneous mixture consists of two or more substances in which a solute is dissolved into another solvent substance. The concentration of a solute in a solution is a measure of how much of the solute is dissolved in the solvent with respect to how much solvent is present.
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Characteristics of Solute
A solution is a homogeneous mixture of two or more substances.
The solute particles in a solution are not visible to the naked eye.
A solution does not cause light beams to scatter.
A solution is stable.
The solute cannot be separated from the solution by filtration (or mechanically).
It is composed of one phase only.
Types of Solute
Homogeneous means that a single phase is formed by the components of the mixture. Heterogeneous means that there are different phases formed by the different components of the mixture.
The properties of the mixture, including concentration, temperature, and density, may be distributed uniformly through the volume, but only in the absence of or after the completion of diffusion phenomena. The three forms of solute are:
Gaseous
Liquid
Solid
Gaseous
In a given set of conditions, if the solvent is gas, then only gases can be dissolved as solutes, and the solution is said to be a gaseous solution. Example: Air is a gaseous solution, nitrogen being the most abundant gas in the air, and all the other gases such as oxygen are dissolved in it.
Liquid
If the solvent is liquid, then all the three forms of matter, solid, liquid, and gas, can be dissolved as a solute in it. Some solute and solvent examples are given below.
Gas in liquid
Oxygen in water
Carbon dioxide in water
Liquid in liquid
Alcoholic drinks are simply water-based ethanol solutions (where ethanol is a solute and water is a solvent.).
Solid in liquid
Sugar solution (Sucrose is a solute added to water which is a solvent)
Salt solution (Sodium chloride is a solute added to water)
Solid
If the solvent is solid, then all the three forms, solid, liquid, and gas, can be dissolved as a solute. Some solute and solvent examples are given below-
Gas in Solid
Hydrogen gets readily dissolved or adsorbed on the surface of the metal, such as palladium.
Liquid in Solid
An amalgam is formed when the mercury as a solute is dissolved in gold.
Moist solids are formed when water is dissolved in solid salt or sugar.
Solid in Solid
Iron, which is essentially a carbon atom solution in a crystalline matrix of iron atoms.
Bronze-like alloys and several others.
Plasticizer - containing polymers.
Examples of Solute and Solutions
A homogenous mixture of two or more substances in relative quantities that can be continuously varied up to what is known as the solubility limit. The word solution is usually applied to the liquid state of matter, but gas and solid solutions are also possible. A solution can be saturated or unsaturated. Saturated solutions are said to be those solutions where no more solute can be dissolved at a particular temperature. Unsaturated solutions are said to be those solutions where more solute can be dissolved at a given temperature.
Did You Know?
We can calculate the concentration of solute and solvent by various methods. Two different units are defined to express the concentration.
Molarity is defined as the number of moles of solute present in 1L of solution. It is denoted by M. Molarity can be expressed as:
M= \[\frac{\text{No of moles of solute}}{\text{mass of solvent in kg}}\]
Molality is defined as the number of moles of solute present in 1kg of solvent. It is denoted by m. Molality can be expressed as-
m= \[\frac{\text{No of moles of solute}}{\text{mass of solvent in kg}}\].
FAQs on Solute
1. What is a solute in chemistry?
A solute is the substance that gets dissolved in another substance, which is called the solvent. In a solution, the solute is typically present in a smaller amount than the solvent. For instance, when making a sugar solution, sugar is the solute and water is the solvent.
2. What is the main difference between a solute and a solvent?
The main difference lies in their roles. The solute is the substance that is being dissolved, while the solvent is the substance that does the dissolving. Generally, the component present in the largest quantity is considered the solvent.
3. Can you give some common examples of solutes?
Yes, here are a few common examples of solutes from daily life:
- Salt when it dissolves in water to make a saline solution.
- Sugar when it dissolves in tea or coffee.
- Carbon dioxide gas which is dissolved in water to create soda and other carbonated drinks.
- Oxygen gas dissolved in water, which is vital for aquatic life to breathe.
4. What happens to solute particles when they dissolve in a solvent?
When a solute dissolves, its individual particles (which can be ions or molecules) break apart from each other and get evenly distributed among the solvent particles. The solvent molecules surround each solute particle, a process known as solvation. This results in a uniform mixture called a solution.
5. In a solution of sugar and water, which is the solute?
In a solution made from sugar and water, sugar is the solute. It is the solid substance that dissolves in the water. Water acts as the solvent in this case because it is the liquid medium that does the dissolving.
6. How does temperature generally affect the solubility of solid solutes?
For most solid solutes, increasing the temperature increases their solubility in a liquid solvent. This happens because the added heat provides more energy to the solvent molecules, allowing them to break the bonds holding the solute particles together more effectively. This is why you can dissolve more sugar in hot water than in cold water.
7. Why do properties like boiling point change depending on the amount of solute?
Properties that depend on the amount of solute particles, not their identity, are called colligative properties. When a solute is added to a solvent, the solute particles physically block the solvent molecules from escaping as a gas. This lowers the solution's vapour pressure. As a result, more energy (a higher temperature) is needed to make it boil, and it must be cooled to a lower temperature to freeze. The more solute particles present, the greater this effect is.
8. Can a substance be a solute in one situation and a solvent in another?
Yes, a substance's role can change depending on the mixture. The component present in the largest quantity is usually considered the solvent. For example, in a solution with 90% ethanol and 10% water, water is the solute. However, in a beverage with 10% ethanol and 90% water, ethanol is the solute.
9. What does the rule "like dissolves like" mean for solutes?
The rule "like dissolves like" is a simple guideline for predicting solubility. It means that substances with similar chemical structures and polarity will dissolve in each other.
- Polar solutes, like table salt (NaCl), dissolve well in polar solvents like water.
- Nonpolar solutes, like oil, do not dissolve in polar solvents like water but will dissolve in nonpolar solvents like gasoline.
