Question

Define: (a) solvent, (b) solute, (c) concentration.

Short answer

A solvent is the substance in largest amount that dissolves the solute. A solute is the substance that is dissolved in a solvent. Concentration is a measure of the amount of solute in a given amount of solvent.

Step-by-step solution

Define Solvent

Identify the component of a solution that is present in the largest amount. It is the substance in which the solute is dissolved to form a solution.

Define Solute

Determine the substance that is dissolved in the solvent. The solute is present in a lesser amount compared to the solvent within a solution.

Define Concentration

Understand concentration as the measure of how much solute is dissolved in the solvent. It expresses the ratio of solute to solvent and can be given in terms like molarity, mass percent, or volume percent.

Key concepts

Solvent

In a solution, the solvent plays a pivotal role as the medium in which other substances, known as solutes, are dissolved. Commonly, it's the component in the greatest quantity. For instance, in a saltwater solution, water is the solvent. One way to remember this is that the solvent 'solves' the solute. It's crucial for students to identify the solvent correctly since it greatly affects solution properties like boiling point and viscosity.

It's also interesting to note that solvents are not limited to liquids; gases and solids can also act as solvents in different types of solutions. However, for most classroom discussions, we often deal with liquid solvents.

Solute

The solute is the substance that gets dissolved in the solvent. It's typically present in a smaller amount relative to the solvent. Taking our saltwater example, salt serves as the solute. Recognizing the solute is crucial when you're calculating concentrations because you'll want to know the quantity of this substance within the solution.

In most educational settings, the solute is what the experiment or chemical reaction is focused on. This can be various substances such as salts, sugars, acids, or bases. Understanding what constitutes a solute helps in grasping concepts like saturation - the point where the solvent can't dissolve any more solute.

Molarity

Moving on to molarity, it's a measurement that specifies the concentration of a solution. Defined as the number of moles of solute per liter of solution, it's denoted using the unit M (molar). The formula to calculate molarity is \( M = \frac{{\text{{moles of solute}}}}{{\text{{liters of solution}}}} \).

This is an essential concept for students to comprehend as it comes up in numerous chemical calculations, particularly when dealing with chemical reactions and stoichiometry. When a problem states a concentration in molarity, you're expected to know exactly how many moles of a substance are present in a given volume of solution, which is crucial for accurate and successful academic outcomes in chemistry.

Mass Percent

Mass percent is another way to express solution concentration. It is the mass of the solute divided by the total mass of the solution, multiplied by 100%. The formula looks like this: \( \text{{Mass percent}} = \frac{{\text{{mass of solute}}}}{{\text{{mass of solute}} + \text{{mass of solvent}}}} \times 100% \).

It's vital in situations where the volume of a solution may change with temperature, but the mass will remain constant. This method is very common in the industries like pharmacology and culinary arts, where precise ratios of ingredients are crucial. Understanding mass percent allows a student to carry out experiments and make solutions where accuracy is paramount.

Volume Percent

Lastly, volume percent is a concept commonly used when both the solute and solvent are liquids. It's calculated by dividing the volume of the solute by the total volume of the solution and then multiplying by 100%. The formula can be stated as \( \text{{Volume percent}} = \frac{{\text{{volume of solute}}}}{{\text{{volume of solute}} + \text{{volume of solvent}}}} \times 100% \).

This concentration term is mostly encountered in the context of alcohol solutions, where bottles of spirits may be labeled with their alcohol content in volume percent. For students, being conversant with volume percent is helpful not only for understanding solutions in chemistry but also for interpreting everyday products like household cleaners and medicinal tinctures.