Purification of KNO3 using Recrystallization

zhmapper
15 Nov 201009:41
EducationalLearning
32 Likes 10 Comments

TLDRIn this educational video, the host demonstrates the recrystallization process to purify potassium nitrate, a common stump remover found in hardware stores. Starting with a saturated solution, the method involves heating to dissolve the compound and cooling to precipitate pure crystals, excluding impurities. The host showcases the solubility data of potassium nitrate, dissolves 453 grams in boiling water, and then cools the solution to observe crystal formation. The process is detailed, including filtration and drying of the resulting potassium nitrate crystals for storage.

Takeaways
  • 🧪 The video demonstrates the process of purifying potassium nitrate through recrystallization.
  • 🔍 Recrystallization involves creating a saturated solution of the substance to be purified, then cooling it to precipitate pure crystals.
  • 🌡️ The solubility of potassium nitrate is temperature-dependent, with higher solubility at 100°C and lower at 0°C.
  • 📊 The script references solubility data for potassium nitrate, showing the significant difference in solubility between high and low temperatures.
  • 💧 The experiment starts with 200 milliliters of boiling water to dissolve a large amount of potassium nitrate.
  • 📦 The potassium nitrate used in the video is a stump remover, a common product found in hardware stores.
  • 🤔 The script notes a humorous observation about the product's packaging marked in fluid ounces instead of grams, despite being a solid.
  • 🕊️ The process of dissolving and then cooling the solution leads to the formation of pure potassium nitrate crystals.
  • 🧊 The video mentions the use of a freezer to expedite the cooling process and promote crystal formation.
  • 🌨️ The recrystallization process is visually described as 'Christmas time in the beaker' due to the continuous precipitation of crystals.
  • 📝 The script describes the setup of a filtration apparatus using a pickle jar and coffee filter to separate the crystals from the solution.
Q & A

  • What is the main topic of the video?

    -The main topic of the video is demonstrating the process of purifying potassium nitrate through recrystallization.

  • What is recrystallization and why is it used for purification?

    -Recrystallization is a process where a saturated solution of a substance is cooled to reduce its solubility, causing the substance to crystallize out of the solution. It is used for purification because crystals form a lattice of the same type of molecule, which is exclusive to impurities, resulting in higher purity.

  • What is the initial step in the recrystallization process shown in the video?

    -The initial step is preparing a saturated solution of potassium nitrate by dissolving it in boiling water.

  • What is the source of potassium nitrate used in the video?

    -The source of potassium nitrate used in the video is a stump remover, which can be found in most hardware stores.

  • What is the solubility of potassium nitrate at 100 degrees Celsius and at 0 degrees Celsius according to the data presented in the video?

    -At 100 degrees Celsius, one liter of solution can contain 2.4 kilograms of potassium nitrate, but at 0 degrees Celsius, it can only contain 133 grams.

  • What is the purpose of heating the water to dissolve the potassium nitrate?

    -Heating the water increases the solubility of potassium nitrate, allowing more of it to dissolve in the water to create a saturated solution.

  • What happens to the potassium nitrate when the solution is cooled down?

    -When the solution is cooled down, the solubility of potassium nitrate decreases, causing it to crystallize out of the solution.

  • What is the purpose of decanting the solution into a smaller beaker?

    -Decanting the solution into a smaller beaker allows for immediate recrystallization to be observed and helps in separating the crystals from the impurities.

  • What is the final step in the recrystallization process shown in the video?

    -The final step is filtration, where the wet crystals of potassium nitrate are separated from the solution using a coffee filter.

  • Why does the video mention the company that makes the potassium nitrate marking the jug in fluid ounces?

    -The video mentions this to highlight a humorous or ironic aspect that the company marking the jug in fluid ounces, despite it being a powdered solid, shows a lack of attention to chemical knowledge or practices.

  • What does the video suggest doing with the remaining solution after the initial crystals have been collected?

    -The video suggests leaving the remaining solution in the refrigerator overnight to allow more crystals to form, which can then be collected and added to the initial batch.

Outlines
00:00
🔬 Purifying Potassium Nitrate Through Recrystallization

In this segment, the video demonstrates the process of purifying potassium nitrate using recrystallization. The presenter explains the concept of recrystallization, which involves creating a saturated solution of the substance to be purified, cooling it to reduce solubility, and allowing pure crystals to form. The experiment uses 200 milliliters of boiling water and potassium nitrate found in stump remover from hardware stores. The presenter also shares solubility data for potassium nitrate, highlighting the significant difference in solubility between 100°C and 0°C. The process begins with dissolving 453 grams of potassium nitrate in the boiling water and then cooling the solution to induce crystal formation. The video captures the initial stages of recrystallization, showing the solution becoming turbid due to impurities and the gradual formation of potassium nitrate crystals.

05:04
🌨 Observing Crystal Formation and Filtration

This paragraph details the ongoing recrystallization process, where the presenter observes the formation of potassium nitrate crystals, comparing the visual to a 'Christmas time in the beaker' with crystals 'snowing' and accumulating at the bottom. The presenter prepares a filtration apparatus using a pickle jar and coffee filter. The intention is to filter the crystals once they have fully formed, with the plan to place the beaker in the fridge to enhance crystal formation. The video then shows the beaker with a significant amount of recrystallized potassium nitrate, with a crust forming on top and the bottom nearly filled with crystals. The presenter discusses the challenges of filtration due to the volume of crystals and decides to decant the top solution and spread the crystals on a glass plate to dry. The process concludes with the presenter expressing satisfaction with the needle-like shape of the crystals, which are ideal for the experiment's purpose, and the intention to dry them overnight for storage in a reagent jar.

Mindmap
Keywords
💡Purification
Purification in the context of the video refers to the process of removing impurities from a substance to increase its purity. It is the main theme of the video, where potassium nitrate is being purified through a specific method called recrystallization. The script describes the process of creating a saturated solution and then cooling it to precipitate pure crystals.
💡Recrystallization
Recrystallization is a technique used to purify substances by dissolving them in a solvent at high temperature and then allowing the solution to cool, so that pure crystals form and can be separated from impurities. In the video, the process is used to purify potassium nitrate, where the script explains the concept and its application in the experiment.
💡Saturated Solution
A saturated solution is one in which the maximum amount of solute has been dissolved in a solvent at a given temperature. In the script, the creation of a saturated solution of potassium nitrate is a critical step in the recrystallization process, where the solubility data is referenced to determine the amount that can be dissolved at different temperatures.
💡Solubility
Solubility is the maximum amount of a solute that can dissolve in a given amount of solvent at a specified temperature. The script discusses the solubility of potassium nitrate at different temperatures, highlighting the significant difference between its solubility at 100 degrees Celsius and at 0 degrees Celsius, which is crucial for the recrystallization process.
💡Potassium Nitrate
Potassium nitrate is a chemical compound with the formula KNO3, used in the video as the substance to be purified. It is mentioned as being found in stump remover products and is the focus of the recrystallization process described in the script.
💡Crystals
Crystals in the video refer to the pure form of potassium nitrate that precipitates out of the solution as it cools. The script describes the formation of these crystals as an exclusionary process for impurities, resulting in a higher purity substance than the original solution.
💡Lattice
A lattice in the context of the video is the three-dimensional arrangement of atoms, ions, or molecules that form the structure of a crystal. The script mentions that crystals form a lattice of the same type of molecule, which is why they are exclusive to impurities and result in a purer substance.
💡Impurities
Impurities are substances or materials that are not wanted in a pure substance and can affect its properties. The script discusses how the recrystallization process helps in removing impurities from potassium nitrate, leading to the formation of pure crystals.
💡Decantation
Decantation is the process of carefully pouring off a liquid from a container, leaving behind any solid material. In the script, decantation is used to separate the purified potassium nitrate crystals from the liquid after recrystallization.
💡Filtration
Filtration is a method to separate solids from liquids by passing the mixture through a filter. The script describes setting up a filtration apparatus using a pickle jar and a coffee filter to collect the purified potassium nitrate crystals after the recrystallization process.
💡Dissolved
To dissolve means to mix a substance with a solvent to form a solution. In the script, the process of dissolving potassium nitrate in boiling water is described as a necessary step before recrystallization can occur.
Highlights

Introduction to the process of purifying potassium nitrate through recrystallization.

Explanation of recrystallization as a method to increase purity by forming crystals from a saturated solution.

Demonstration of preparing 200 milliliters of boiling water for the recrystallization process.

Research on solubility data for potassium nitrate at different temperatures.

Observation of the distinct solubility curve for potassium nitrate from 0 to 100 degrees Celsius.

Preparation of potassium nitrate solution by dissolving 453 grams in boiling water.

Mislabeling of the potassium nitrate container in fluid ounces instead of grams.

Dissolving the entire container of potassium nitrate and observing the temperature drop.

Decanting the solution into a smaller beaker to observe immediate recrystallization.

Visual demonstration of potassium nitrate crystals forming and falling out of the solution.

Setting up a filtration apparatus using a pickle jar and coffee filter for recrystallization.

Placing the beaker in the fridge to maximize crystal formation.

Decanting the top layer of the solution and transferring wet potassium nitrate crystals.

Observation of the crystals' needle-like structure and their formation process.

Spreading the crystals on a glass plate to dry overnight.

Plan to repeat the process with the remaining solution for further purification.

Conclusion of the video with a summary of the recrystallization process and its outcome.

Transcripts

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Chemistry LabRecrystallizationPotassium NitratePurification MethodEducational VideoScience ExperimentCrystal GrowthLab TechniquesSolubility DataDIY Science