Solubility vs Concentration - Basic Introduction, Saturated Unsaturated and Supersaturated Solutions

The Organic Chemistry Tutor
9 Nov 201713:20
EducationalLearning
32 Likes 10 Comments

TLDRThis video offers an insightful introduction to the concept of solubility, differentiating it from concentration. Solubility is defined as the maximum amount of solute that can be dissolved in a solvent at a given temperature, measured in units like grams per liter. In contrast, concentration refers to the amount of solute present in a solution, which can vary infinitely. The video explains three types of solutions: unsaturated (where concentration is less than solubility), saturated (equal to solubility), and supersaturated (exceeding solubility). It also demonstrates how to calculate the concentration of a solution and determine its type based on solubility. Using potassium nitrate as an example, the video illustrates how solubility changes with temperature and how to create a supersaturated solution by dissolving a solute at high temperature and then cooling it down.

Takeaways
  • 📊 **Solubility vs. Concentration**: Solubility and concentration share the same units (e.g., molarity, molality, mass percent) but represent different concepts. Concentration is the amount of solute in a given volume of solution, while solubility is the maximum amount that can be dissolved per liter at a specific temperature.
  • 🔍 **Solubility Defined**: Solubility is the maximum concentration that can be achieved by dissolving a solute in a solvent at a certain temperature, with a specific example being the solubility of KNO3 at 20°C being 330 grams per liter.
  • ♨️ **Temperature's Role**: The solubility of most ionic compounds increases with temperature, which is a key factor in determining the concentration and type of solution.
  • 🚿 **Unsaturated Solution**: An unsaturated solution occurs when the concentration is less than the solubility, meaning more solute can still dissolve.
  • 🈵️ **Saturated Solution**: A saturated solution is one where the concentration equals the solubility, and no more solute can dissolve at that temperature.
  • 🔝 **Supersaturated Solution**: A supersaturated solution has a concentration that exceeds the solubility limit, which can occur when a solution is cooled after being heated to dissolve more solute than normally possible.
  • 💠 **Solution Equilibrium**: At saturation, the solution is in equilibrium, and adding more solute will not increase its concentration in the solution but will increase the mass of undissolved material.
  • 🔽 **Precipitation in Supersaturated Solutions**: Supersaturated solutions can lead to precipitation if more solute is added or if the solution is disturbed, potentially crystallizing into a solid.
  • ⚖️ **Calculating Concentration**: The concentration of a solution is calculated by dividing the mass of the solute by the volume of the solvent in liters.
  • 🔮 **Determining Solution Type**: By comparing the concentration to the solubility at a given temperature, one can determine if a solution is unsaturated, saturated, or supersaturated.
  • 🧊 **Creating a Supersaturated Solution**: A supersaturated solution can be made by dissolving a solute at a high temperature, where solubility is high, and then cooling the solution to a lower temperature where solubility is less, thus exceeding the solubility limit at the cooler temperature.
Q & A

  • What is the primary difference between solubility and concentration?

    -Solubility refers to the maximum amount of solute that can be dissolved in a solvent at a given temperature, while concentration describes the amount of solute that is actually present in a solution.

  • What units are commonly used to express both solubility and concentration?

    -Common units for expressing solubility and concentration include molarity (moles per liter), molality (moles per kilogram of solvent), normality, and mass percent.

  • What is the solubility of KNO3 at 20 degrees Celsius?

    -The solubility of KNO3 at 20 degrees Celsius is 330 grams per liter.

  • What are the three types of solutions based on their concentration relative to solubility?

    -The three types of solutions are unsaturated (concentration < solubility), saturated (concentration = solubility), and supersaturated (concentration > solubility).

  • What happens when you add more solute to a saturated solution?

    -When you add more solute to a saturated solution, no additional solute will dissolve. Instead, the excess solute will remain as an undissolved solid.

  • How can a supersaturated solution be formed?

    -A supersaturated solution can be formed by dissolving as much solute as possible at a higher temperature and then cooling the solution to a lower temperature where the solubility is less.

  • What is the concentration of a solution if you have 50 grams of solute in 250 milliliters of water?

    -To find the concentration, you convert 250 milliliters to liters (0.25 liters) and then divide the grams of solute by the volume in liters. For 50 grams in 0.25 liters, the concentration is 200 grams per liter.

  • If the solubility of a substance at a certain temperature is known, can the concentration of a solution at that temperature exceed the solubility?

    -No, the concentration of a solution cannot exceed the solubility at a given temperature because solubility is the maximum amount of solute that can be dissolved.

  • What is the difference between an unsaturated and a supersaturated solution?

    -An unsaturated solution has a concentration less than the solubility, meaning more solute can still dissolve. A supersaturated solution has a concentration greater than the solubility, which is unstable and can lead to precipitation or crystallization.

  • How can you determine if a solution is unsaturated, saturated, or supersaturated without conducting an experiment?

    -You can determine the type of solution by comparing the known concentration of the solution to the solubility of the solute at the given temperature. If the concentration is less than the solubility, it's unsaturated; if equal, it's saturated; and if greater, it's supersaturated.

  • What happens to the solubility of most ionic compounds when the temperature increases?

    -For most ionic compounds, solubility increases with an increase in temperature.

  • If you have a supersaturated solution and you add a seed crystal, what might happen?

    -Adding a seed crystal to a supersaturated solution may cause the excess solute to crystallize and precipitate out of the solution.

Outlines
00:00
🧪 Understanding Solubility and Concentration

This paragraph introduces the concept of solubility and distinguishes it from concentration. Both are measured in similar units like molarity (moles per liter), molality, normality, and mass percent. Solubility refers to the maximum amount of solute that can be dissolved in a solvent at a given temperature, while concentration indicates the amount of solute that is currently dissolved in the solution. The solubility of KNO3 at 20°C is given as 330 grams per liter, serving as an example to illustrate that solubility is the maximum concentration achievable. The paragraph also explains the difference between unsaturated, saturated, and supersaturated solutions, highlighting that an unsaturated solution has less solute than the solubility limit, a saturated solution has reached the solubility limit, and a supersaturated solution has more solute than the solubility limit but remains in solution.

05:02
📊 Calculating Solution Concentration and Type

The paragraph demonstrates how to calculate the concentration of a solution given the mass of the solute and the volume of the solvent. It uses the solubility of potassium nitrate (KNO3) at 20°C and 70°C as examples to show how to determine if a solution is unsaturated, saturated, or supersaturated. For a solution at 20°C with 50 grams of KNO3 in 250 mL (0.25 liters) of water, the concentration is 200 grams per liter, which is less than the solubility of 330 grams per liter, indicating an unsaturated solution. The same logic is applied to other scenarios, with calculations showing how the concentration compares to solubility at different temperatures and solute amounts, resulting in different types of solutions.

10:03
🔍 Creating a Supersaturated Solution

This paragraph explains the process of creating a supersaturated solution. It begins by dissolving a solute in a solvent at a high temperature where the solubility is greater, such as dissolving 250 grams of KNO3 in 200 mL (0.2 liters) of water at 70°C, resulting in a concentration of 1250 grams per liter, which is less than the solubility of 1300 grams per liter, thus an unsaturated solution. When the temperature is then lowered to 20°C, the solubility decreases to 330 grams per liter, but the concentration remains at 1250 grams per liter, leading to a supersaturated solution. The paragraph emphasizes that supersaturated solutions are unstable and can crystallize when disturbed or when a seed crystal is introduced. To create a supersaturated solution, one must dissolve as much solute as possible at high temperature and then cool the solution to a lower temperature where the solubility is less.

Mindmap
Keywords
💡Solubility
Solubility refers to the maximum amount of solute that can be dissolved in a solvent at a given temperature to form a saturated solution. It is a key concept in the video, as it distinguishes the limit of how much substance can be dissolved. For instance, the solubility of potassium nitrate at 20 degrees Celsius is 330 grams per liter, meaning no more than this amount can be dissolved in one liter of water at that temperature.
💡Concentration
Concentration indicates the amount of solute present in a given volume of solution, often expressed in units like molarity (moles per liter) or mass per liter. It is central to the video's theme as it describes the current state of a solution, whether it is unsaturated, saturated, or supersaturated. For example, a concentration of 200 grams per liter of a substance in water is less than its solubility, making it an unsaturated solution.
💡Molarity
Molarity is a unit of concentration that expresses the number of moles of solute per liter of solution. It is one of the units used to measure concentration in the video and is important for understanding how much solute is in a given volume of solvent. The video uses grams per liter, which is conceptually similar to molarity when considering the mass of the solute.
💡Unsaturated Solution
An unsaturated solution is one in which the concentration of solute is less than the solubility at a given temperature. It is a fundamental concept in the video, illustrating a state where more solute can still be dissolved. For example, if the concentration of a solution is 200 grams per liter and the solubility is 330 grams per liter, the solution is unsaturated.
💡Saturated Solution
A saturated solution is one where the concentration of solute equals the solubility at a given temperature, meaning no more solute can be dissolved. It is a critical point discussed in the video, representing a state of equilibrium where the amount of dissolved solute is at its maximum. If the concentration equals the solubility value, such as 330 grams per liter at 20 degrees Celsius, the solution is considered saturated.
💡Supersaturated Solution
A supersaturated solution contains more solute than the solubility limit at a given temperature, but the excess solute does not precipitate out. This state is unstable, as demonstrated in the video, and the solution can become supersaturated by dissolving a solute at a higher temperature and then cooling the solution, leading to a concentration greater than the solubility at the lower temperature.
💡Equilibrium
Equilibrium in the context of the video refers to a state where a saturated solution has reached a balance, and no more solute can be dissolved at a given temperature. It is a state of dynamic balance where the rate of dissolution equals the rate of precipitation. The video illustrates this by stating that if you add more solute to a saturated solution, it will not dissolve but instead remain undissolved.
💡Precipitation
Precipitation is the process by which a solute comes out of solution and forms a solid. It is related to the concept of supersaturated solutions in the video, where adding more solute to such a solution can lead to the formation of crystals, indicating that the solution has become too concentrated and the excess solute is no longer stable in solution.
💡Temperature Effect
The effect of temperature on solubility is a significant theme in the video. It explains how the solubility of most ionic compounds increases with temperature, which is why the solubility of potassium nitrate is higher at 70 degrees Celsius (1300 grams per liter) than at 20 degrees Celsius (330 grams per liter). The video also demonstrates how cooling a solution can lead to supersaturation.
💡Mass Percent
Mass percent is a unit of concentration that represents the percentage of the total mass of a solution that is made up of the solute. It is one of the various forms of concentration mentioned in the video, used to describe the amount of solute in a solution. While not explicitly used in the calculations, it is an important concept for understanding different ways to express concentration.
💡Seed Crystal
A seed crystal is a small, already-formed crystal that can be added to a supersaturated solution to induce precipitation. The video discusses how the presence of a seed crystal can trigger the crystallization process, causing the supersaturated solution to become stable by forming a solid phase.
Highlights

Solubility and concentration share the same units but represent different concepts.

Concentration measures the amount of solute in a solution, while solubility is the maximum that can be dissolved.

Solubility is temperature-dependent and has a specific value, unlike concentration which can vary infinitely.

The solubility of KNO3 at 20°C is 330 grams per liter, defining the maximum concentration achievable at that temperature.

An unsaturated solution has a concentration less than solubility, favoring further dissolution.

A saturated solution has a concentration equal to solubility, with no more solute able to dissolve.

A supersaturated solution has a concentration exceeding solubility, potentially leading to precipitation.

The concept of equilibrium in a saturated solution is explained, where no additional solute will dissolve.

The process of creating a supersaturated solution involves dissolving solute at a high temperature and then cooling.

The solubility of potassium nitrate increases with temperature, with values of 330 grams per liter at 20°C and 1300 grams per liter at 70°C.

Calculation methods for determining the concentration of a solution are demonstrated using the formula: concentration = grams of solute / liters of solution.

The difference between the amount of solute in solid and aqueous phase in a saturated solution is calculated.

A supersaturated solution can be unstable and may crystallize upon the addition of a seed crystal or a shock.

The video provides a step-by-step guide to understanding and calculating solubility, concentration, and solution types.

The importance of understanding the relationship between temperature, solubility, and concentration is emphasized for solving problems.

Practical applications of solubility concepts are discussed, such as making supersaturated solutions.

The video concludes with a comprehensive understanding of how to identify unsaturated, saturated, and supersaturated solutions.

Transcripts

Browse More Related Video

Solubility Curves - Basic Introduction - Chemistry Problems

Solubility Curves and Practice Problems

Unsaturated, Saturated, and Supersaturated Solutions

Solutions: Table G (Solubility Curves)

Solutions: Table G (Solubility Curves) - Guided Practice

Concentration and Molarity explained: what is it, how is it used + practice problems

Rate This

5.0 / 5 (0 votes)

Thanks for rating:

Related Tags
Solubility BasicsChemical ConceptsConcentration UnitsMolarityMass PercentUnsaturated SolutionSaturated SolutionSupersaturated SolutionPotassium NitrateTemperature EffectChemical Equilibrium