How do you separate a mixture of gold nuggets from iron filings and sodium?

Answer 1

The separation of gold from iron filings and sodium metal (a dangerous substance which will react with water in the air) could be done in two steps. Take a magnet and put it inside a plastic bag. Carefully and fully move the bagged magnet over the mixture, gently stirring it to insure the magnet can "reach" all the iron filings. When you are done, lift the magnet clear of the mixture, and you should have all the iron filings stuck to the magnet, which is inside the bag. If you carefully "invert" the bag, you'll then have the bag around the filings, which will still be stuck to the magnet with a layer of plastic bag between the two. Then just close the bag and remove the magnet. Your iron filings have been separated and bagged up. Now turn your attention to the gold and sodium mixture. Put them in a big heavy plastic container. If you *carefully* add water, you will get a chemical reaction. It is *critical* to put water in a drop at a time. (Yes, a drop at a time.) The sodium will react with the water and create sodium hydroxide, which is powerful base. It will also create a lot of heat, so you have to take all day to drop in the water so it won't melt your bucket. There will be some strong fumes, too, so take precautions. The bucket, because it is plastic, won't react with the sodium hydroxide. After you spend all day dripping the water into the mixture to react with all the sodium, you'll have a solution of sodium hydroxide with the gold in it. Strain this mixture and the gold will remain in the sieve. You'll need to wear a ton of protection to perform this evolution. Rinse your gold well to remove the traces of the sodium hydroxide and you're in business.