Solutions - Online Tutor, Practice Problems & Exam Prep

Solutions are homogeneous mixtures composed of solutes and solvents that form a uniform composition, where the solute is the substance dissolved in the greater amount of solvent. Concentration measures the amount of solute in a solution. Unlike solutions, suspensions are heterogeneous mixtures with large particles over 500 nanometers that can settle out due to gravity, while colloids are homogeneous mixtures with intermediate-sized particles less than 500 nanometers that remain suspended. Examples include Italian salad dressing as a suspension, where oil, vinegar, herbs, and spices can be seen floating, and milk as a colloid, where fat and proteins like casein are suspended throughout the liquid. Understanding the differences between solutions, suspensions, and colloids is fundamental in chemistry, particularly when discussing the properties and behaviors of mixtures.

Solutions

Solutions represent homogeneous or homogeneous mixtures made-up two 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 500ML 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, and 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 intermediately sized particles that can also float within a solvent. Now when it comes to their particle sizes, we're going to say for suspension the particles are larger, so they tend to be greater than 500 nm in terms of size. And for colloids, they tend to be less than 500 nm.

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 coiloids, though their particles are not as large. So these these particles, they 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 a great examples of suspensions and colloids. Well, a great example for a suspension could be Italian salad dressing, because an Italian salad dressing, what do we have? We have oil. We have vinegar. What else do we have? Oops. Vinegar. Vinegar. We have herbs. We have spices and if you really look at a tiling dressing, you can see those particles floating around within the liquid.

Examples of colloids we have. A great example would be milk. Now in milk you have suspended within the liquid portion of it you have like fat cells, fat particles, you have Cassian. You have a lot of different things that are suspended within the milk itself and these things are constantly floating within milk. They don't sell on the top or the bottom all right. 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 homogeneous mixture where the solute and solvent have blended perfectly together and you can't tell them apart. The only mission that shows this would be option B. Option B is a solution. The solute and solvent and mix perfectly together and you can't tell them apart for the next one.

Here for a what do we have? We have are solvent and then we see these little spheres, these little particles, and these are our solute particles floating around. All right. So here we would say when we have this going on, this would be a colloid, cause 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 represent.

Here’s what students ask on this topic:

What is a solution?

A solution is a homogeneous mixture composed of two or more substances. In such a mixture, a solute is a substance that is dissolved in another substance, known as the solvent. The solvent is typically the component present in greater quantity. For example, in a saltwater solution, salt is the solute that is dissolved in water, the solvent.

Solutions can exist in different phases: they can be gaseous (like air), liquid (like saline water), or solid (like alloys). The concentration of a solution is a measure of the amount of solute that is dissolved in a given quantity of solvent. This can be expressed in various ways, such as molarity, which is moles of solute per liter of solution, or mass percent, which is the mass of the solute divided by the total mass of the solution, multiplied by 100%.

The ability of a solute to dissolve in a solvent depends on the physical and chemical properties of both substances and the conditions under which the solution is formed, such as temperature and pressure. Solutions are important in many scientific fields, including chemistry, biology, and physics, and are integral to numerous processes in everyday life.

What is a solute?

A solute is a substance that is dissolved in a solvent to form a solution. In the context of chemistry, when you mix two substances together, the solute is the component that is present in a smaller amount and becomes dispersed within the solvent, which is the component present in a larger amount. For example, when you stir a spoonful of sugar into a glass of water, the sugar is the solute, and the water is the solvent. The process of dissolving involves the solute particles being surrounded by solvent molecules, which can occur through various interactions such as hydrogen bonding, ion-dipole forces, or Van der Waals forces, depending on the nature of the solute and solvent. The resulting homogeneous mixture is called a solution, where the solute cannot be seen separately from the solvent. Solutes can be gases, liquids, or solids, and the concentration of a solute in a solution can vary depending on the amount dissolved in the solvent.

What is a solvent?

A solvent is a substance that has the ability to dissolve other substances, creating a solution. In a solution, the solvent is typically the component present in the greatest amount, and it determines the phase of the solution (solid, liquid, or gas). The substances that dissolve in the solvent are called solutes.

The most common solvent is water, known as the "universal solvent" because it can dissolve a wide range of substances due to its polar nature. Solvents can be categorized into two main types: polar solvents (like water, alcohol, and acetone) and non-polar solvents (such as benzene, toluene, and hexane). The choice of solvent is crucial in chemical reactions and processes because it can influence the rate and the outcome of the reaction. The saying "like dissolves like" often applies, meaning that polar solvents are good at dissolving polar solutes, and non-polar solvents are better at dissolving non-polar solutes.

What is concentration?

Concentration refers to the amount of a substance in a given quantity of a mixture or solution. It can be expressed in several ways, such as molarity, molality, mass percent, volume percent, or parts per million (ppm). Molarity is perhaps the most commonly used measure in chemistry and is defined as the number of moles of solute (the substance being dissolved) per liter of solution. It's denoted by the unit M (molar). Molality, on the other hand, is the number of moles of solute per kilogram of solvent and is used when the solution's temperature is expected to change, as it doesn't vary with temperature. Mass percent is the mass of the solute divided by the total mass of the solution, multiplied by 100 to get a percentage. Volume percent is similar but uses volume instead of mass. Parts per million is used for very dilute solutions and indicates the number of parts of solute per million parts of the solution. Understanding concentration is crucial in fields such as chemistry, biology, and environmental science, as it helps predict how substances will interact in a solution.

What is the difference between a suspension and a colloid?

A suspension and a colloid are both mixtures, but they differ in the size of the particles and their behavior in the mixture.

A suspension is a heterogeneous mixture where the particles are relatively large and will settle out over time due to gravity. An example of a suspension is sand in water; if left undisturbed, the sand particles will eventually settle to the bottom. Suspensions are not stable and the particles can be separated by filtration.

On the other hand, a colloid is a type of mixture where the particle size is intermediate, larger than molecules but too small to settle out under the influence of gravity. Colloids are stable and the particles do not settle out upon standing. They exhibit the Tyndall effect, which is the scattering of light by the particles in the colloid, making a beam of light visible in the mixture. An example of a colloid is milk, which has fat particles dispersed in water. Colloids cannot be separated by simple filtration and require more complex methods like centrifugation.