In this video we dissolve a Platinum Bar in a combination of hydrochloric and nitric acids better known as aqua regia.

First the 1 ounce platinum bar is covered with 200mL of 12M hydrochloric acid (about 37%). Then 25mL of 15M nitric acid (~70%) is added. The mixture is gently heated to near boiling. The acid will bubble as it reacts. Chemical gas bubbling like this looks more like fizzing and is distinct from boiling. When the bubbling almost stops (~4 hours) add another 25mL of nitric acid. Repeat as necessary. The dissolution is very slow and may take days for a compact bar of platinum. This reaction is usually much quicker for small bits of platinum scrap or powder. If more then 75mL of nitric acid has been added then alternate subsequent acid additions with 50mL hydrochloric acid and 25mL nitric acid. This is because both hydrochloric and nitric acids are consumed in side reactions.

Eventually the platinum will dissolve into a red liquid while hot and when cooled will be an orange liquid. This crude solution of chloroplatinic acid and unreacted nitric and hydrochloric acids may be further processed into purified chloroplatinic acid.