How do you prepare a 0.1 M oxalic acid solution for a galvanic cells lab?

Weigh 6.304 g of oxalic acid dihydrate and transfer it to an Erlenmeyer flask. Add 500 mL of deionized water, then stir until homogeneous. Use a powder funnel to transfer the solution to a labeled polyethylene bottle and store it in the instructor's hood. Handle oxalic acid with caution as it is corrosive.

What materials are needed to prepare a salt bridge for a galvanic cell experiment?

Cut string into 2-inch pieces, with three pieces needed per group. Soak the strings in a 0.1 M potassium nitrate solution for one hour before the lab begins. This prepares the salt bridge, which maintains electrical neutrality between the two half-cells in the galvanic cell.

How should metal electrodes be prepared before use in a galvanic cells experiment?

Cut copper sheet into 2 x 9 cm pieces, zinc sheet into 2 x 6 cm pieces, and silver sheet into 2 x 6 cm pieces. Store each metal type in labeled beakers corresponding to unknown numbers. Clean metal surfaces with emery paper cut into 1 x 2 inch pieces to remove oxidation before assembly.

What is the correct procedure for preparing unknown solutions in a galvanic cells lab?

Prepare 0.05 M zinc sulfate by weighing 3.6 g and dissolving in 250 mL deionized water. Prepare 0.22 M silver nitrate by weighing 9.34 g and dissolving in 250 mL deionized water. Divide each solution into two brown glass bottles labeled with corresponding unknown numbers and store in the instructor's hood.

What equipment should be set up at each lab station for a galvanic cells experiment?

Each station requires a multimeter with leads, alligator clips, glass thermometer, 6-well reaction plate, forceps, volumetric flasks, graduated cylinders, beakers, glass funnels, and a 20-mL volumetric flask. These tools enable students to measure solutions, monitor voltage, and assemble electrochemical cells for data collection.

How do you prepare the potassium nitrate solution for the salt bridge?

Weigh 2.53 g of potassium nitrate and transfer to a flask. Add 250 mL of deionized water and stir until homogeneous. Transfer the 0.1 M solution to a labeled glass bottle and store in the instructor's hood. Use this solution to soak salt bridge strings one hour before the lab.

What safety and waste management procedures are required for a galvanic cells lab?

Wear appropriate personal protective equipment including a lab coat, chemical splash goggles, and gloves. Handle oxalic acid with caution as it is corrosive. Dedicate a 20-L container for heavy metal waste and ensure it is accessible in the hood for safe disposal of all metal-containing solutions and materials.

原电池

概念教师准备学生实验方案

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电化学反应是指电子在两种物质之间发生转移的过程，其中一种物质失去电子，另一种物质获得电子。当一种物质失去电子时，我们称其发生了氧化，或称其被氧化；当它获得电子时，我们称其发生了还原，或称其被还原。为了帮助区分这两个过程，可以记住短语“oil rig”，其含义是：氧化是失去（oxidation is losing），还原是获得（reduction is gaining）。某些电化学反应会自发进行，我们可以通过原电池来研究这类反应。

原电池包含四个主要部分。首先，有两个金属电极，每个电极分别浸入不同的电解质溶液中。这些溶液含有在各电极上发生的半反应（即氧化反应或还原反应）所需的离子。溶液之间通过盐桥连接，盐桥允许离子流动并维持溶液的电荷中性。电极之间通过外部电路连接，反应过程中电子经由该电路传递。

阳极是在反应中释放电子或被氧化的电极。阴极是获得电子并被还原的电极。为了帮助区分这两个标签，可以记住短语“red cat”（还原发生在阴极）。

那么，我们如何判断哪种金属作为阳极，哪种金属作为阴极呢？我们可以利用金属的标准电极电势，它用于衡量金属失去电子的倾向。电极电势越负，表明该金属越容易失去电子。电子总是从标准电极电势较低的金属流向标准电极电势较高的金属。

在原电池中，电子从阳极流向阴极，因此阳极是标准电势较低的金属，而阴极是标准电势较高的金属。当电子在两个电极之间移动时，会产生电势差。所产生的电压大小等于阴极的标准电势减去阳极的标准电势。

因此，如果在原电池中使用两种标准电极电位相近的金属，例如铅和锡，所产生的电压将较低。如果金属的标准电位差异较大，例如银和镁，则产生的电压将较高。

在本实验中，您将使用两种金属电极构建一个原电池，并在氧化和还原反应发生时测量所产生的电势。然后，您将利用已知的标准电极电势来鉴定未知的金属电极，并确定所产生的电压大小。

At the end of this lab, students should know...

什么是电化学？

电化学是化学的一个分支，研究化学反应与电能之间的关系。

电化学电池的关键组成部分是什么？

电化学电池由包含电解质溶液的反应室（或多个反应室）、盐桥以及两个通过电路连接的导电电极（阳极和阴极）组成。

在电化学电池中，氧化和还原反应发生的位置是什么？

氧化还原反应（或称redox反应）由一对半反应组成，其中一个物种在氧化过程中失去电子，而另一个物种在还原过程中获得电子。还原反应发生在阴极，氧化反应发生在阳极。

原电池与电解池有何区别？

电解池利用外部电源提供的电能来驱动非自发反应。而在原电池中，自发的化学反应产生电能。