# Electroplating

> A current turns metal ions into a metal coat


## Objectives

- Describe electroplating: a current through a solution of metal ions coats an object with that metal.
- Explain why, in electroplating, the object to be coated is the cathode, joined to the negative terminal.
- Predict the metal of the coat from the ions in the solution.

## 1. Alloys and their types




## 2. A copper coat from a solution

Predict: where did the copper coat come from?

- The iron of the key changed into copper
- Copper dust in the liquid stuck to the key
- Copper ions in the solution became copper metal on the key ✓

The copper coat came from the copper ions in the solution: the current drove them to the key, where they gained electrons and became copper metal.

[ar-EG] طبقة الـ copper جاية من الـ copper ions اللي في الـ solution: الـ current ساقها ناحية المفتاح، وهناك كسبت electrons واتحوّلت لـ copper metal.
## 3. What electroplating is

Electroplating Coating an object with a thin metal layer by passing a current through a solution of that metal's ions. The object is joined to the negative terminal. The positive metal ions are attracted to it.


## 4. At the cathode

Cathode The electrode where reduction (gain of electrons) happens, in every cell. In electroplating, it is the plate joined to the negative terminal: the object to be coated. Time (stage) At the cathode (reduction): each copper ion gains two electrons Electrons reach the key from the battery. Each copper ion gains two and becomes a copper atom. The coat grows.


## 5. Coat or no coat?

The object goes on the positive terminal. The coat is made of the metal whose ions are in the solution. Does the object get a metal coat?


## 6. Check yourself

You want to coat a spoon with silver. Which setup works?

- Spoon joined to −, in a solution of copper ions
- Spoon joined to +, in a solution of silver ions
- Spoon joined to −, in a sugar solution
- Spoon joined to −, in a solution of silver ions ✓

To coat a spoon with silver, the spoon is joined to − and dipped in a solution of silver ions: the positive silver ions move to the spoon, gain electrons and deposit as silver.

[ar-EG] عشان تغطي معلقة بالـ silver، المعلقة بتتوصّل بالـ − وتتحط في solution فيه silver ions: الـ silver ions الـ positive بتتحرك ناحية المعلقة، وبتكسب electrons وتترسّب silver.
## 7. Summary

Electroplating: a current through a solution of metal ions coats an object with that metal. In electroplating, the object is the cathode: it is joined to the negative terminal. At the cathode, metal ions gain electrons (reduction) and become atoms. Next: with ions of two metals, both deposit at once. The book prepares alloys this way. Can you explain why the object goes on the negative terminal? The metal ions are positive, so they are attracted to the negative terminal and pushed away from the positive one. At the object they gain electrons and become the metal coat.



Chapter: Transition Elements (https://yaani.ai/en/learn/chemistry/chem-s3-en.ch1)
Source: https://yaani.ai/en/lesson/chem-s3-en.lesson-chem.electroplating-basic