What is molarity and molality Class 11? | What is molality and example? | calculate molality

source of skills
23 Sept 202303:05
EducationalLearning
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TLDRThis animated video from the YouTube channel 'Source of Skills' explains the concepts of molarity and molality, two measures of solution concentration. It begins by defining concentration as the amount of solute dissolved in a given amount of solvent. The video then introduces molarity, which is the number of moles of solute per liter of solution, and provides an example of making a 10 molarity HCL solution. Molality is also discussed, defined as the number of moles of solute per kilogram of solvent, with a demonstration of creating a 10 molality HCL solution. The video clarifies that molarity does not consider the solvent's volume, whereas molality accounts for the solvent's mass, helping viewers differentiate between these two important chemical concepts.

Takeaways
  • 🧪 Concentration is a measure of how much solute is dissolved in a given amount of solvent.
  • 📝 Molarity and molality are two terms used to measure the concentration of a solution.
  • 📦 Molarity is defined as the number of moles of solute in one liter of solution, with the solvent not being considered.
  • 🔍 The formula for molarity is the number of moles of solute over the volume of the solution.
  • 🧪 An example of calculating molarity is creating a 10 molarity solution of HCL by adding 10 moles of HCL to a one-liter beaker and then filling it with water to the one-liter mark.
  • 📦 Molality is defined as the number of moles of solute in 1 kg of solvent, with the solvent being considered in the calculation.
  • 🔍 The formula for molality is the number of moles of solute over the mass of the solvent.
  • 🧪 An example of calculating molality is creating a 10 molality HCL solution by weighing out 1 kg of distilled water and adding 10 moles of HCL to it.
  • 🔄 Understanding the difference between molarity and molality is crucial for accurately measuring and comparing solution concentrations.
  • 🌡 Molarity is volume-dependent, which means it can change with temperature, whereas molality is mass-dependent and remains constant regardless of temperature.
  • 📚 The video provides a clear explanation and examples to help viewers distinguish between molarity and molality.
Q & A

  • What is the main topic of the video?

    -The main topic of the video is to explain the concepts of molarity and molality, which are two different ways to measure the concentration of a solution.

  • What is concentration in the context of a solution?

    -Concentration refers to the amount of solute that is dissolved in a given amount of solvent.

  • How does the video illustrate the difference in concentration between two solutions?

    -The video uses an example of two beakers with equal amounts of water, where 5 grams of table salt is added to the first beaker and 10 grams to the second, showing the first as less concentrated and the second as more concentrated.

  • What is molarity and how is it represented?

    -Molarity is a measure of the number of moles of solute in one liter of solution. It is represented by the capital letter 'M' and is calculated as the number of moles of solute divided by the volume of the solution in liters.

  • How is molarity calculated in the video example with HCl?

    -In the video example, to make a 10 molarity solution of HCl, 10 moles of HCl are added to a one-liter beaker and then distilled water is added to reach the one-liter mark, resulting in a molarity of 10 M.

  • What is molality and how does it differ from molarity?

    -Molality is a measure of the number of moles of solute in 1 kg of solvent. Unlike molarity, which considers the volume of the solution, molality takes into account the mass of the solvent.

  • How is molality represented and what is its formula?

    -Molality is represented by the lowercase letter 'm' and its formula is the number of moles of solute divided by the mass of the solvent in kilograms.

  • Can you provide an example of how to prepare a solution with a specific molality as shown in the video?

    -In the video, to prepare a 10 molality HCl solution, a 1-liter empty beaker is weighed with 1 kg of distilled water, and then 10 moles of HCl are added to it.

  • Why might molality be preferred over molarity in certain situations?

    -Molality might be preferred over molarity when the solution's concentration needs to be temperature-independent, as molality is based on mass, which does not change with temperature, unlike volume.

  • What is the significance of using a weight balance in the molality example?

    -The weight balance is used to ensure that exactly 1 kg of distilled water is used in the preparation of the 10 molality HCl solution, which is crucial for achieving the desired concentration.

  • How does the video conclude the explanation of molarity and molality?

    -The video concludes by summarizing the key points of molarity and molality, highlighting their formulas and the importance of understanding both for measuring solution concentrations.

Outlines
00:00
🧪 Introduction to Molarity and Molality

This animated video from the YouTube channel 'Source of Skills' introduces the concepts of molarity and molality, two methods for measuring the concentration of a solution. The video begins by explaining the concept of concentration, which is the amount of solute dissolved in a given amount of solvent. An example is provided using two beakers of water with different amounts of dissolved table salt to illustrate the difference between a less concentrated and a more concentrated solution. The video then defines molarity as the number of moles of solute in one liter of solution, emphasizing that the solvent is not considered in this measurement. Molarity is represented by the symbol 'M' and is calculated as the number of moles of solute divided by the volume of the solution. An example is given to demonstrate how to create a 10 molarity solution of HCL. Molality is then introduced as the number of moles of solute in 1 kg of solvent, with the solvent being considered in this measurement. Molality is represented by the lowercase 'm' and is calculated as the number of moles of solute over the mass of the solvent. The video concludes with an example of how to prepare a 10 molality HCL solution, using a weight balance and a specific amount of distilled water and HCL.

Mindmap
Keywords
💡Concentration
Concentration in the context of this video refers to the amount of solute that is dissolved in a given amount of solvent. It is central to understanding the theme of the video, which is about measuring the concentration of solutions. The script uses the example of two beakers with equal amounts of water, where different amounts of table salt are added to illustrate different levels of concentration, with one solution being less concentrated and the other more concentrated.
💡Molarity
Molarity is a key term in the video and is defined as the number of moles of solute per liter of solution. It is a measure of concentration that does not consider the volume of the solvent. The script explains molarity through the formula 'number of moles of solute over volume of solution' and provides an example of making a 10 molarity HCL solution by adding 10 moles of HCL to a one-liter beaker and then filling it with water to the one-liter mark.
💡Molality
Molality is another important term discussed in the video, which measures the number of moles of solute in 1 kg of solvent. Unlike molarity, molality takes into account the mass of the solvent. The script illustrates molality with the formula 'number of moles of solute over mass of solvent' and an example of creating a 10 molality HCL solution by weighing exactly 1 kg of distilled water and adding 10 moles of HCL to it.
💡Solute
A solute is the substance that is dissolved in a solvent to form a solution. In the video, table salt and HCL are used as examples of solutes. The concept of solute is essential for understanding the video's theme as it is the component being measured in different concentration scales like molarity and molality.
💡Solvent
A solvent is the substance that dissolves a solute to form a solution. Water is used as the solvent in the examples provided in the script. The role of the solvent is crucial in the context of the video as it is the medium in which the solute is dissolved, and its volume or mass is used to calculate molarity or molality, respectively.
💡Beaker
A beaker is a type of laboratory glassware used to mix, stir, or heat substances. In the video, beakers are used to demonstrate the process of making solutions with different concentrations of solute. The script describes adding solute to beakers and using them to measure out the volumes and masses for molarity and molality calculations.
💡Table Salt
Table salt, or sodium chloride, is used in the script as an example of a solute. It is added to water in different amounts in two beakers to show how concentration can vary. The use of table salt helps to visually demonstrate the concept of concentration in a relatable and easily understandable way.
💡HCL
Hydrochloric acid (HCL) is used in the script as an example of a solute for which molarity and molality solutions are prepared. The video explains how to make a 10 molarity and a 10 molality HCL solution, using it to illustrate the calculation and preparation of solutions with specific concentration measures.
💡Mole
A mole is a unit of measurement used in chemistry to express amounts of a chemical substance, defined as the amount containing the same number of particles as there are in 12 grams of carbon-12. In the video, moles are used in the formulas for both molarity and molality to quantify the amount of solute in a solution.
💡Distilled Water
Distilled water is water that has been purified through distillation, removing impurities and minerals. In the script, distilled water is specified for use in preparing the HCL solutions to ensure that the only solute present is HCL, and the solvent is pure. This allows for accurate molarity and molality measurements.
💡Weight Balance
A weight balance is a device used to measure the mass of an object. In the context of the video, a weight balance is used to measure exactly 1 kg of distilled water for preparing a molality solution. This tool is essential for ensuring the accuracy of the molality calculation.
Highlights

Introduction to the concept of molarity and molality.

Definition of concentration as the amount of solute dissolved in a given amount of solvent.

An example illustrating the difference between less concentrated and more concentrated solutions.

Introduction of molarity as a method to measure solution concentration.

Explanation that molarity does not consider the solvent.

Molarity formula presented as moles of solute over volume of solution.

Example of creating a 10 molarity HCL solution.

Introduction of molality as another method to measure solution concentration.

Molality considers the mass of the solvent in its calculation.

Molality formula presented as moles of solute over mass of solvent.

Example of creating a 10 molality HCL solution using a weight balance.

Emphasis on the importance of accurately measuring 1 kg of distilled water for molality.

Demonstration of combining 10 moles of HCL with 1 kg of water to achieve the desired molality.

The video concludes with a reminder of the key differences between molarity and molality.

Invitation to like and subscribe for more informative videos.

The video provides a clear distinction between molarity and molality with practical examples.

Transcripts

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MolarityMolalityConcentrationChemistryEducationalAnimatedVideoSoluteSolventConcentration Measurement