碘法和碘化法之间的差异

Thekey difference在碘化法和碘化方面是we can use Iodometry to quantifyoxidizing agents, whereas we can use iodimetry to quantify reducing agents.

Iodometry and iodimetry are two common滴定methods useful in analytical chemistry. The basis of these two types of titrations is oxidation-reduction, and we can use it to determine redox species quantitatively. The basis of titration is a reaction between the analyte and a standard reagent known as the titrant. We can determine the quantity of the analyte if we know the reaction, stoichiometry and the volume/mass of the titrant needed to react completely with the analyte. Moreover, we can use iodine for this氧化还原滴定由于其反应能力快很多pecies. Reversibility of iodine/iodide, the reaction is also an advantage when using them in iodometric reactions.

CONTENTS

1.Overview and Key Difference
2.What is Iodometry
3.What is Iodimetry
4.Side by Side Comparison – Iodometry vs Iodimetry in Tabular Form
5.概括

What is Iodometry?

In iodometry, iodides react with another oxidizing agent in an acidic medium or neutral medium. When this reaction takes place, iodide (we add iodide in the form of KI) oxidizes to iodine and the other species will undergo reduction by iodide. Then we can titrate the released iodine with another species. This titrating species is a standard solution of a reducing agent, which is capable of reducing iodine back to iodide form. Usually, we use a standard thiosulphate solution for this. For example, if we want to quantify the amount of chlorine dissolved in a mixture, the following is the method to carry out an iodometric titration.

首先，我们应该从混合物（将氯溶解的混合物）中取出一定数量的体积。然后，我们可以用已知的Ki解决方案对其进行滴定，我们可以找到所消耗的量。

Following the redox reaction will take place in the reaction flask;

Cl₂+ 2I^–- > 2 Cl^–+ I₂

Then we should carry out another titration with the same mixture to determine the released amount of iodine. For this, we can titrate the mixture with a standard thiosulphate solution. We need to add starch as an indicator, to determine the end point of this reaction. With iodine and starch in the mixture, it will appear in dark-blue colour, but at the end point when all the iodine is finished, the dark colour will disappear.

I₂+ 2 S₂O₃²⁻→ S₄O₆²⁻+ 2 I^–

从上面的两个滴定中，我们可以确定CL的量₂.

什么是碘法？

In iodimetry, it uses free iodine to undergo titration with a reducing agent. Therefore, iodine reduces to iodide, and iodine will oxidize other species.

Since we cannot easily prepare a free iodine solution, we have to mix iodine with potassium iodide and KI₃解决所需解决方案的解决方案。并将其用于碘化滴定的标准解决方案。

KI+I₂→ki₃

Following reaction takes place when titrating. We can use starch as an indicator for iodometric titrations too.

I₂+ reducing agent → 2 I^–

What is the Difference Between Iodometry and Iodimetry?

碘量计学是通过添加对形成碘反应的碘化物来对氧化剂的溶液进行定量分析，然后滴定是滴定的，而碘化合物是一种体积分析，涉及具有标准化溶液的滴定溶液，或者是由碘的标准化溶液，或者是由碘的释放释放的。碘的可溶性形式，以便我们可以通过滴定来确定其浓度。这是碘法和碘化法之间的一个区别。

Furthermore, another difference between iodometry and iodimetry is that, in iodometry, iodides react with another oxidizing agent in an acidic medium or neutral medium while in iodimetry, it uses free iodine to undergo titration with a reducing agent.

The below infographic presents the difference between iodometry and iodimetry in tabular form.

概括– Iodometry vs Iodimetry

尽管两个术语的碘化指定和碘化法听起来相似，但它们是我们在分析化学中使用的两种不同的技术。碘化指定和碘化法之间的关键区别在于，我们可以使用碘量指定来量化氧化剂，而我们可以使用碘化法来量化还原剂。

Reference:

1. “Iodometry.” Wikipedia, Wikimedia Foundation, 9 Sept. 2018.Available here
2. Naviglio, Daniele. “Iodometry and Iodimetry, Daniele Naviglio « Analytical Chemistry « Agraria « Federica e-Learning.” Federica, Federica Web Learning, Università Di Napoli Federico II, 20 Mar. 2012.Available here

Image Courtesy:

1.”Iodometric titration mixture”By LHcheM – Own work, (CC BY-SA 3.0)viaCommons Wikimedia
2.”School level titration demonstration”By UCL – Flickr,（CC由2.0）viaCommons Wikimedia