Making a "Gold" Penny - A Copper/Zinc Alloy (Brass) скачать в хорошем качестве

Making a "Gold" Penny - A Copper/Zinc Alloy (Brass)

The alloy brass can be made by melting copper and zinc metals together to form a homogeneous mixture. In the video we start with a regular penny and then add it to a solution of aqueous sodium hydroxide (NaOH). Zinc powder is also added to the solution. The mixture is heated and the dissolved zinc coats the penny giving it a silver appearance. Once the penny is coated with zinc we can heat it in a Bunsen burner until the zinc layer melts into the copper beneath. When this happens the penny becomes gold colored. The gold is actually brass, a mixture of zinc and copper. If we left the penny coated in zinc it would eventually react with the oxygen in the air and corrode. The alloy brass will retain this color indefinitely. --- Drawing done in Adobe Illustrator and captured with Camtasia Studio on a Microsoft Surface Pro 3. Audio recording using a Yeti Blue microphone.