Weighing on an Analytical Balance, A Chemistry Lab Demo From Thinkwell
TLDRThis video demonstrates the use of an analytical balance, also known as a tear balance or electronic balance, for precise measurement in the laboratory. It highlights its ability to weigh down to a tenth of a milligram, explains the tear feature for measuring added substances, and shows practical weighing techniques using both plastic weigh boats and weighing paper. The video emphasizes the importance of accuracy, neatness, and proper handling of the balance to maintain its precision and longevity.
Takeaways
- 🔍 The script introduces an analytical balance, also known as a tear balance or electronic balance, used for precise weighing in a laboratory setting.
- 📊 The balance has an electronic readout that measures to the tenth of a milligram, showcasing its high precision for weighing small quantities.
- 📝 Demonstrates the 'tear' feature (spelled T-R), which resets the balance to zero, allowing for the weighing of differences, such as the weight of ink on a piece of paper.
- 📋 The script explains the process of weighing a piece of paper, writing on it, and then weighing it again to show the tear feature in action.
- 🌬 Discusses the sensitivity of the balance to environmental factors like air drafts, which can affect its readings.
- 🧪 Introduces plastic weigh boats and weighing paper as tools for weighing substances in a lab, with instructions on how to prepare and use them.
- 🏷 Explains the technique of folding weighing paper to create a crease, which can be used as a chute for transferring materials.
- 📐 Describes how to use a scoopula to transfer solid materials to the weighing paper, emphasizing the importance of not returning excess reagent to the original bottle.
- 📦 Shows how to weigh both small and large amounts of substances, using potassium permanganate and salt as examples.
- 🔄 Highlights the importance of being neat and cleaning up after using the balance to prevent damage to the sensitive instrument.
- 💡 The script concludes with a reminder to take care of the analytical balance, as some substances weighed can be corrosive and damaging if not handled properly.
Q & A
What is an analytical balance and what are its alternative names?
-An analytical balance is a highly precise instrument used in laboratories for weighing chemicals. It is also known as a 'tear balance' or an 'electronic balance.'
What is the level of precision that an analytical balance can achieve?
-An analytical balance can weigh with a precision down to one-tenth of a milligram (0.1 mg).
What is the 'tear' feature of an analytical balance and how is it used?
-The 'tear' feature, spelled T-E-A-R, allows the balance to reset to zero after an item has been weighed, which is useful for subtracting the weight of a container or paper and only weighing the contents.
How does the script demonstrate the precision of the analytical balance?
-The script demonstrates the precision by weighing a piece of paper before and after writing on it, showing the balance can detect the small weight of the ink.
How can air drafts in a laboratory affect the performance of an analytical balance?
-Air drafts can cause the balance to fluctuate and give inaccurate readings due to the disturbance of air currents around the balance.
What are plastic weigh boats and how are they used in a laboratory?
-Plastic weigh boats are convenient containers for weighing substances in a laboratory. They are ready to use and can hold the substance directly for weighing.
What is weighing paper and how should it be used?
-Weighing paper is a thin wax paper used for weighing substances. It should be folded in quarters to create a crease, which helps to contain the substance and can act as a chute for transferring it.
What is potassium permanganate and why was it chosen for the demonstration in the script?
-Potassium permanganate is a strong oxidizing agent. It was chosen for the demonstration because of its highly colored nature, which makes it easy to see and demonstrate the weighing process.
How should excess reagent be handled after weighing?
-Excess reagent should not be transferred back to the original bottle to avoid contamination. Instead, it should be placed in a clean container for potential future use.
What technique is demonstrated for weighing a larger amount of a substance like 5 grams of salt?
-The script demonstrates a technique where the substance is poured directly from the reagent bottle into a weighing boat, using a rolling motion to control the amount transferred.
Why is it important to be neat and clean when using an analytical balance?
-Being neat and clean prevents damage to the sensitive instrument and avoids contamination from corrosive or hazardous substances that may be weighed.
Outlines
🔬 Introduction to the Analytical Balance and its Features
The script introduces an analytical balance, also known as a tear or electronic balance, used for precise weighing of chemicals in a laboratory setting. It highlights the balance's electronic readout, which can measure to the tenth of a milligram, showcasing its high precision. The presenter demonstrates the balance's 'tare' feature, which resets the weight to zero, allowing for the measurement of the ink's weight on a piece of paper by writing on it and weighing again. The script also discusses the impact of air drafts on the balance's accuracy, emphasizing the need for a controlled environment.
📝 Techniques for Weighing Substances in a Laboratory
This paragraph details the process of weighing substances using an analytical balance, focusing on two techniques: using a scoopula to weigh out small amounts and pouring directly for larger amounts. The script explains how to use plastic weighing boats and weighing paper, which is folded to create a crease for easy transfer of substances. It also covers the importance of not transferring excess reagent back to the original bottle and the method of 'sneaking up' on a desired weight by tapping the scoopula or container. The paragraph concludes with a demonstration of weighing potassium permanganate and household salt, illustrating the balance's use for both small and large quantities, and emphasizes the importance of cleanliness and maintenance of the balance.
Mindmap
Keywords
💡Analytical balance
💡Tare feature
💡Electronic readout
💡Weighing by difference
💡Plastic weigh boats
💡Weighing paper
💡Air currents
💡Potassium permanganate
💡Scoopula
💡Clean Beaker
Highlights
Introduction to an analytical balance, also known as a tear balance or electronic balance, used for precise weighing in laboratories.
The balance has an electronic readout with the capability to weigh to the tenth of a milligram.
Demonstration of the tear feature, which resets the balance to zero for convenience in subsequent weighings.
Weighing by difference technique to determine the weight of ink on a piece of paper.
Impact of air drafts on the balance's precision and a demonstration of this effect.
Use of plastic weigh boats for convenient weighing of substances in the lab.
Introduction to weighing paper, a thin wax paper used for weighing, and its proper handling and storage.
Technique for folding weighing paper to create a crease for easy transfer of substances.
Weighing out a small amount of potassium permanganate using a scoopula and the balance's precision.
Avoiding the transfer of reagent back to the original bottle to prevent contamination.
Technique for adjusting the amount of substance weighed by tapping the scoopula or container.
Weighing a larger amount of a substance, such as 5 grams of salt, using a weighing boat.
Method of rolling the reagent container to control the amount transferred during weighing.
The importance of neatness and cleanliness when using the analytical balance to prevent damage.
The use of the crease in weighing paper or the bend in a weigh boat to transfer substances quantitatively.
Emphasis on the need for careful maintenance of the analytical balance due to its sensitivity and precision.
Transcripts
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