Solutions: Study with Video Lessons, Practice Problems & Examples

Solutions are homogeneous mixtures consisting of a solute, which is the smaller component, and a solvent, the larger component that dissolves the solute. Concentration measures the amount of solute in a solution. In contrast, suspensions are heterogeneous mixtures with larger particles that can settle, while colloids contain intermediate-sized particles that remain suspended. Examples include Italian salad dressing as a suspension and milk as a colloid. Understanding these distinctions is crucial for grasping concepts in chemistry, particularly in relation to mixtures and their properties.

Solutions

Solutions represent homogeneous mixtures made up of 2 or more components that form a uniform composition. Now when we say "uniform composition," that means that everything mixes perfectly together. So when I take a look at the result, I can't tell which part is which. Everything is mixed perfectly together. Now when it comes to solutions, we have portions of it that we need to understand. First, we have our solute. The solute represents the smaller portion of the solution that is dissolved within the solvent. The solvent itself is the part of the solution that is present in the larger amount and it can dissolve other substances. "Concentration" is a word that you will hear oftentimes. Concentration is basically a measurement of the amount of solute that you have present in a given solution. So speaking about solutions, let's take a look at this solution formation image. The smaller ball there, it's smaller in amount, so it represents our solute. This solute, I'm going to dunk it into this solvent, let's just assume it's water, which is larger in amount, then you need to realize when you have a solute dissolving in a solvent, they create a purple solution in this case, which is our solution. So just remember, solutions are homogeneous mixtures and it's solute added to solvent that helps to create them.

Solutions Example 1

Here it says, if 10 grams of sodium chloride is dissolved in 500 mL of water, identify the solute and the solvent. Remember, the solute is the smaller portion of our solution. It's the quantity that's lower in amount. So here we're going to say that our solute within this question would have to be the 10 grams of sodium chloride. And then here the solvent is the larger portion that does the dissolving. The larger portion here is the water. So water here would be our solvent. So within this question, our solute again is sodium chloride and our solvent is water. Together they form our solution.

Solutions

We just said that solutions represent homogeneous mixtures. And when it comes to mixtures, solutions aren't the only important term to remember. We also have suspensions and colloids. Now suspensions represent heterogeneous mixtures. In these heterogeneous mixtures, we have large solute particles that have the potential to float within the solvent. Then we have colloids. Colloids represent yet another homogeneous mixture. The difference now though, in solutions, the particles completely dissolve within our solvent, so they're not easy to see. But in a colloid, they're intermediate-sized particles that can also float within a solvent.

Now when it comes to their particle sizes, we're going to say for suspensions, the particles are larger so they tend to be greater than 500 nanometers in terms of size. And for colloids, they tend to be less than 500 nanometers. Now because of their increased size, because they're larger, these particles will eventually settle, and they could settle either on the top or on the bottom. Where they settle really depends on the density of the solvent. But all you need to remember is that when it comes to suspensions, the particles being larger means they can eventually settle. Colloids, though, have particles that are not as large. So, these particles never settle. They never settle on the top or the bottom. They kind of stay suspended somewhere in the middle of the solvent.

Now, what are great examples of suspensions and colloids? Well, a great example for a suspension could be Italian salad dressing. Because in Italian salad dressing, what do we have? We have oil, vinegar, herbs, and spices. And if you really look at Italian dressing, you can see those particles floating around within the liquid. Examples of colloids, a great example would be milk. Now in milk, you have fat cells, fat particles, and casein suspended within the liquid portion of it. These things are constantly floating within the milk. They don't settle on the top or the bottom.

Alright. So just remember, solutions are homogeneous mixtures, but mixtures also can talk about suspensions and colloids.

Solutions Example 2

In this example, it says, "From the following images, identify a solution, suspension, and colloid." So let's do the easy part first. A solution. Remember, a solution is a homogeneous mixture where the solute and solvent have blended perfectly together and you can't tell them apart. The only image that shows this would be option B. Option B is a solution. The solute and solvent have mixed perfectly together, and you can't tell them apart.

For the next one here, for A, what do we have? We have our solvent, and then we see these little spheres, these little particles, and these are our solute particles floating around. Alright. So here we would say when we have this going on, this would be a colloid. Because a colloid is a homogeneous mixture with smaller, and we're going to have smaller size solute particles like we have here. That would mean that C would have to be our suspension. Our suspension is a heterogeneous mixture, we're going to have larger solute particles because they're larger, they're going to settle closer to the bottom. So we'd say A is a colloid, B is a solution, and C is a suspension. That's how we say each one of these jars or each one of these containers represents.

Here’s what students ask on this topic:

What is the difference between a solute and a solvent in a solution?

A solute is the smaller component of a solution that gets dissolved, while a solvent is the larger component that dissolves the solute. For example, in a saltwater solution, salt is the solute, and water is the solvent. The solvent's role is to break down the solute particles and distribute them evenly, creating a homogeneous mixture. Understanding the roles of solute and solvent is crucial for grasping how solutions form and behave.

How do you calculate the concentration of a solution?

Concentration is calculated by dividing the amount of solute by the volume of the solution. The formula is:

$\frac{\mathrm{amount} \mathrm{of} \mathrm{solute}}{\mathrm{volume} \mathrm{of} \mathrm{solution}}$

For example, if you have 5 grams of salt dissolved in 100 milliliters of water, the concentration is 5 grams per 100 milliliters, or 0.05 grams per milliliter. Concentration can also be expressed in molarity (moles of solute per liter of solution), which is commonly used in chemistry.

What are the key differences between solutions, suspensions, and colloids?

Solutions are homogeneous mixtures where the solute is completely dissolved in the solvent, making it impossible to distinguish between the two. Suspensions are heterogeneous mixtures with large solute particles that can settle over time. Colloids are homogeneous mixtures with intermediate-sized particles that remain suspended and do not settle. Examples include saltwater (solution), Italian salad dressing (suspension), and milk (colloid). Understanding these differences helps in identifying and working with various types of mixtures in chemistry.

Why do particles in a suspension eventually settle, but not in a colloid?

In a suspension, the particles are larger (greater than 500 nanometers) and have enough mass to overcome the solvent's ability to keep them suspended, causing them to settle over time. In contrast, colloid particles are smaller (less than 500 nanometers) and are kept suspended by the continuous motion of the solvent molecules, preventing them from settling. This distinction is important for understanding the stability and behavior of different types of mixtures.

Can you provide examples of common solutions, suspensions, and colloids?

Common examples of solutions include saltwater and sugar dissolved in water. Examples of suspensions include Italian salad dressing, where you can see particles like herbs and spices floating. Milk is a classic example of a colloid, containing fat particles and proteins suspended in water. These examples help illustrate the differences in particle size and behavior among solutions, suspensions, and colloids.