Name: calibrating lab glassware for accurate volume
Uploaded: 2024-12-05T18:31:54.000Z
Duration: 1 min 11 s
Channel: JoVE

准确的体积测量对于基于溶液的分析至关重要。标准的容量仪器包括烧瓶、移液管和滴定管。
容量瓶用于配制和稀释特定体积的溶液。其上标有“TC”，表示“容纳” &#34;包含。&#34;
它们经过校准，可在指定温度下容纳精确的体积，此时玻璃膨胀系数最小，即使温度发生微小变化，体积也几乎保持恒定。
标有TD的移液管可在指定温度下输送特定体积的液体。其校准考虑了玻璃管壁上液膜的排出，而液膜排出量随输送时间变化。
经过适当校准的移液管可准确移取单一固定体积，精确度可达四位或五位有效数字。量出式移液管可移取不同体积，但准确度较低，最多可达三位有效数字。
滴定管是一种用于盛装滴定剂的校准管，可通过手动阀门系统精确释放滴定剂，以控制滴定剂的流速。

玻璃器皿校准

准确校准玻璃器皿，例如容量瓶、移液器和滴定管，对于确保分析实验室的准确测量至关重要。校准有助于保持测量的一致性，并防止因体积不准确而产生误差。


 容量瓶


 容量瓶旨在准确制备精确体积的水溶液，瓶颈处有校准线。为了校准容量瓶，需要用蒸馏水填充，直到弯月面（液体的曲面）与校准标记对齐。在眼睛水平处观察弯月面可确保读数准确。校准通常在特定温度（~20°C）下进行，以考虑温度对体积的影响。如果水位高于标准线，则需小心地排水，直到达到标准线；如果水位低于该线，则需逐滴添加更多的水，直到达到标准线。校准后，可以通过称量水的重量，并将其与基于密度的理论值进行比较来确认烧瓶的容量。


 移液器


 移液器用于转移特定体积的液体。


 容量移液器：这些移液器旨在提供单一、高精度的体积，通常精确到四位或五位有效数字。为了进行校准，首先用要测量的溶液清洁和冲洗移液器，填充至校准标记，并让其完全排入容器中。然后通过称量输送的水，并将其与基于水密度的理论体积进行比较来检查准确性。


 刻度移液器：与容量移液器不同，刻度移液器标有一系列线条，可以提供多个体积，但精度略低 - 通常最多三位有效数字。在校准和测量期间还必须仔细观察弯月面。


 滴定管


 滴定管是一种长的刻度玻璃管，一端有一个控制阀，可以准确分配不同量的溶液，特别是在滴定中。校准滴定管时，确保滴定前后弯月面与标记正确对齐，并通过将输送的水的重量与其理论值进行比较来检查分配的体积是否符合预期。滴定管的储液器上有标记以指示液体的体积。底部的旋塞作为控制阀，允许用户控制储液器的液体流量，从而精确测量分配的量。


 其他玻璃器皿


 其他类型的实验室玻璃器皿，例如量筒，也常用于体积测量，但精度低于体积设备。它们通常提供高达三位有效数字的体积，适用于无需太精确的工作。然而，校准这些物品对于保持测量可靠性仍然很重要。


 校准实验室玻璃器皿可确保准确可靠的测量，这对于保持分析结果的完整性至关重要。无论是使用容量瓶、移液器、滴定管还是其他玻璃器皿，正确的校准技术都有助于防止错误并提高实验室工作的精度。

准确校准玻璃器皿（如容量瓶、移液管和滴定管）对于确保分析实验中的测量准确性至关重要。

Education

教育

JoVE Core

Analytical Chemistry

分析化学

Unit 1

第一单元

Method Development and Sampling Techniques

方法开发与采样技术

method-development-and-sampling-techniques

KEY TERMS AND CONCEPTS

关键术语与概念

Glassware Calibration

calibrating lab glassware for accurate volume

Calibrating lab glassware helps students measure liquids accurately in the analytical laboratory. It reduces volume errors and supports consistent results across measurements. This matters when using volumetric flasks, pipettes, burettes, and other tools that depend on precise volume readings.

Volumetric flasks are used to prepare aqueous solutions with a precise final volume. They have a calibration line on the neck. To calibrate one, fill it with distilled water until the meniscus, the curved surface of the liquid, lines up with the mark at eye level. This is usually done at about 20°C because temperature can affect volume. If the water rises above the line, drain it carefully. If it is below the line, add water drop by drop until it reaches the mark. The flask’s capacity can then be checked by weighing the water and comparing it with the theoretical value from its density.

Pipettes are used to transfer set amounts of liquid. Volumetric pipettes are made to deliver one highly accurate volume, often to four or five significant figures. To calibrate one, clean it and rinse it with the solution to be measured, fill it to the calibration mark, and let it drain completely into a container. The volume delivered is checked by weighing the water and comparing it with the theoretical volume based on water density. Graduated pipettes have a series of marks and can deliver different volumes, but they are slightly less accurate. They are generally used to about three significant figures, so the meniscus must still be read carefully.

Burettes are long, graduated glass tubes with a tap at one end. They are used to dispense variable amounts of solution, especially during titrations. When a burette is calibrated, the meniscus must be aligned with the markings before and after use. The volume dispensed is then compared with the expected value by weighing the water delivered. The reservoir shows the liquid level, and the stopcock, or tap, acts as a manual valve that controls flow for precise measurement.

Other glassware, such as graduated cylinders, is also used for measuring volume. These tools are less accurate than volumetric equipment, but they are still useful for work that does not need the highest precision. They usually measure up to three significant figures. Even so, calibration remains important for reliable measurements in the lab. Careful calibration of lab glassware helps protect the accuracy and integrity of analytical results.

Calibrating Lab Glassware for Accurate Volume

calibrating-lab-glassware-for-accurate-volume

development of analytical methods

Analytical Methods: Technique to Protocol

Analytical methods follow a clear path from technique to protocol. In analytical chemistry, a technique is the scientific principle used to explain a chemical measurement. A method applies that technique to a sample of interest. The next steps are procedure and protocol. A procedure gives the directions for carrying out the analysis with an analytical method. A protocol is the detailed set of guidelines for that procedure, and it should be followed closely to get the desired results. <br...

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Quality Control Charts and Lab Records

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Quality Checks in Analytical Testing

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How Analytical Methods Are Checked

Method validation checks whether an analytical chemistry method gives reliable results. It is especially important when the same method is used with different sample matrices or when the procedure is changed. Validation helps show that the method still meets acceptable standards in each case. Several key checks are used in method validation. Specificity means the method can measure the target analyte without interference from other substances. Linearity means the result changes in direct...

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Classical and Instrumental Sample ID

Qualitative analysis identifies the elements, ions, or compounds in an unknown sample. It is the first step in the hierarchy of analytical goals. That makes it the starting point for scientific study before quantitative analysis or other forms of analysis. Two main approaches are used in qualitative analysis: classical methods and instrumental methods. Classical methods depend on the visible or sensory result of a chemical reaction, such as a color change, a precipitate, or even a smell. These...

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Measuring Analyte Concentration

Quantitative analysis measures the amount of a specific substance, called the analyte, in a sample. If the sample composition is unknown, qualitative analysis comes first. That step identifies the components so the correct substances can be measured during the quantitative phase. This method depends on two key measurements. Scientists measure the sample quantity and also a property that is proportional to the amount of analyte. Together, these measurements help determine the analyte...

instrument calibration

Calibrating Lab Instruments for Accurate Results

Calibration helps lab instruments produce accurate and consistent results. It is important in manufacturing, healthcare, testing laboratories, and scientific research. Each instrument needs a calibration process that matches its design and function. This process improves data accuracy and helps results stay reliable. An analytical balance measures mass and needs regular calibration to stay precise. It is calibrated by comparing its readings with known standard weights. These weights act as...

glassware calibration

Calibrating lab glassware helps students measure liquids accurately in the analytical laboratory. It reduces volume errors and supports consistent results across measurements. This matters when using volumetric flasks, pipettes, burettes, and other tools that depend on precise volume readings. Volumetric flasks are used to prepare aqueous solutions with a precise final volume. They have a calibration line on the neck. To calibrate one, fill it with distilled water until the meniscus, the...

standard solutions

Preparing Standard Solutions in the Lab

Standard solutions are prepared to have a precisely known concentration or composition. In analytical chemistry, this accuracy is important because it supports reliable results. A primary standard is a highly pure, stable substance with a high molar mass. It is fully soluble in water, which is the most commonly used solvent in analytical chemistry. A primary standard solution can be used to standardize a secondary standard. Secondary standards have known concentrations, but they are usually...

blank solutions

Blank Solutions in Analytical Testing

Blank solutions are used in analytical testing to show the background signal before a sample is measured. A blank solution does not contain the analyte, which is the substance of interest being tested or measured. It is usually made with the same reagents and procedure as the sample solution, but without the analyte. The main purpose of a blank solution is to control for background interference and contamination. Reagents, solvents, or lab equipment can sometimes create a detectable signal on...

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sampling methods: sample types

Sampling Materials in Solid, Liquid, Gas

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sampling plans

Choosing Samples for Reliable Results

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sample preparation for analysis: overview

Preparing Samples by State and Form

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sample-preparation-for-analysis-advanced-techniques

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sample handling

Sample Transport and Storage Basics

Sample transport and storage help keep specimens intact before testing. Moving a sample from the collection point to the laboratory requires careful handling. The sample should be sealed well and clearly labeled. These steps help prevent cross-contamination and support reliable results. Temperature control is also important during transport. Some samples travel in insulated containers, cool packs, or refrigerated vehicles so they stay within the needed temperature range. After the samples...

contaminants and errors

Sampling Errors in Sample Preparation

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key terms and concepts

Learn how volumetric flasks, pipettes, burettes, and graduated cylinders are calibrated to improve volume accuracy, consistency, and lab reliability.

Calibrating Lab Glassware for Accurate Volume | JoVE K12

analytical chemistry

JoVE Core Analytical Chemistry simplifies complex chemical principles by breaking them down into clear, engaging animations, making topics from SI Units to NMR spectroscopy more accessible and straightforward. Additionally, the scientist-in-action videos highlight the application of these concepts in real-world research conducted in laboratories globally.

Calibrating Lab Glassware for Accurate Volume

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