equivalence point

简明释义

当量点

英英释义

例句

1.The graph of pH versus volume of titrant shows a sharp increase at the equivalence point.

pH与滴定剂体积的图表在当量点处显示出急剧上升。

2.To accurately find the equivalence point, a burette is used to add titrant slowly.

为了准确找到当量点，使用滴定管缓慢添加滴定剂。

3.During a titration, the chemist determined that the equivalence point was reached when the solution turned pink.

在滴定过程中，化学家确定当溶液变为粉红色时达到了当量点。

4.The equivalence point indicates the exact moment in a reaction where the amount of reactants is stoichiometrically equivalent.

当量点表示反应中反应物的量在化学计量上相等的确切时刻。

5.In acid-base titrations, the equivalence point is often identified using a pH indicator.

在酸碱滴定中，通常使用pH指示剂来识别当量点。

作文

In the realm of chemistry, the concept of the equivalence point plays a crucial role in titration experiments. A titration is a laboratory method used to determine the concentration of a particular substance in a solution. During this process, a reactant, known as the titrant, is gradually added to a solution containing the analyte until the reaction reaches completion. The equivalence point, which is the stage at which the amount of titrant added is stoichiometrically equivalent to the amount of substance present in the analyte, is a key indicator of this completion.Understanding the equivalence point is essential for chemists, as it allows them to accurately calculate the concentration of unknown solutions. For instance, consider an acid-base titration where hydrochloric acid (HCl) is titrated against sodium hydroxide (NaOH). The equivalence point occurs when the number of moles of HCl equals the number of moles of NaOH, resulting in a neutral solution. At this point, the pH of the solution will be approximately 7, indicating that the acid and base have completely reacted with each other.The determination of the equivalence point can be visualized through the use of a pH indicator or a pH meter. Indicators are substances that change color at specific pH levels, thus providing a visual cue for the chemist. In the case of the aforementioned titration, phenolphthalein is often used, which transitions from colorless in acidic solutions to pink in basic solutions. The moment the solution turns from colorless to pink signifies that the equivalence point has been reached, allowing the chemist to stop the titration.However, it is important to note that the equivalence point should not be confused with the endpoint of the titration. The endpoint is the point at which the indicator changes color, which may happen slightly before or after the actual equivalence point. Therefore, careful selection of indicators and precise titration techniques are vital to ensure accurate results.Beyond its significance in titrations, the equivalence point also has broader implications in various fields of chemistry and biochemistry. For example, in the formulation of pharmaceuticals, knowing the equivalence point can help in determining the correct dosages of active ingredients. Similarly, in environmental chemistry, understanding the equivalence point can aid in assessing water quality by determining the presence of contaminants.In conclusion, the equivalence point is a fundamental concept in analytical chemistry that serves as a pivotal marker in titration processes. Its accurate identification is crucial for calculating concentrations and ensuring the success of experiments. By mastering the understanding of the equivalence point, chemists can enhance their analytical skills and contribute significantly to various scientific fields. Thus, the study of the equivalence point not only enriches our knowledge of chemical reactions but also underscores the importance of precision and accuracy in scientific research.

在化学领域，等效点的概念在滴定实验中发挥着至关重要的作用。滴定是一种实验室方法，用于确定溶液中特定物质的浓度。在这个过程中，逐渐向含有分析物的溶液中添加一种称为滴定剂的反应物，直到反应达到完成。等效点是指添加的滴定剂的量在化学计量上等于分析物中存在的物质的量，这是完成反应的关键指标。理解等效点对化学家至关重要，因为它使他们能够准确计算未知溶液的浓度。例如，考虑一个酸碱滴定，其中盐酸（HCl）与氢氧化钠（NaOH）进行滴定。等效点发生在HCl的摩尔数等于NaOH的摩尔数时，从而产生中性溶液。在这一点上，溶液的pH值将大约为7，表明酸和碱已经完全反应。通过使用pH指示剂或pH计，可以可视化地确定等效点。指示剂是指在特定pH值下改变颜色的物质，从而为化学家提供视觉线索。在上述滴定的情况下，通常使用酚酞，它在酸性溶液中呈无色，在碱性溶液中呈粉红色。溶液从无色变为粉红色的那一刻标志着等效点的到达，使化学家可以停止滴定。然而，重要的是要注意，等效点不应与滴定的终点混淆。终点是指指示剂改变颜色的点，这可能发生在实际等效点之前或之后。因此，仔细选择指示剂和精确的滴定技术对于确保结果的准确性至关重要。除了在滴定中的重要性外，等效点在化学和生物化学的各个领域也具有更广泛的意义。例如，在药物配方中，了解等效点可以帮助确定活性成分的正确剂量。同样，在环境化学中，理解等效点可以帮助评估水质，以确定污染物的存在。总之，等效点是分析化学中的基本概念，是滴定过程中的关键标志。准确识别其位置对于计算浓度和确保实验成功至关重要。通过掌握对等效点的理解，化学家可以提升他们的分析技能，并对各个科学领域做出重要贡献。因此，对等效点的研究不仅丰富了我们对化学反应的知识，还强调了精确性和准确性在科学研究中的重要性。