With Hydrochloric acid 10 Moles per L or 31 percent with any Nitrate salt (Magnesium Nitrate, Calcium Nitrate, Sodium Nitrate, etc- expect ammonia nitrate due to the ammonia base) you can make weak Aqua Regas.
It is an alternative to using Sulfuric acid and makes a good material that can dissolve gold, copper, brass, iron, silver and antimony metal very well.
A good hot plate (distillation, etc) is required for this Project and Sand bath is required to reflux the HCL and Nitrate salt.
WARNING: Never add Hydrogen peroxide 3 to 35 percent or Potassium Permagnate to this Aqua Regas since it can release Toxic Chlorine (from HCl) and NO2 gas (Nitric oxide) from (NNO3). Avoid mixing these at all cost. Nitrate salts are powerful oxidizers and can explode with fuel and heat.
Hydrochloric acid and sodium carbonate are very corrosive.
Step 1: Calculating the Amount of Magnesium Nitrate for Aqua Regas Needed.
First here the Chemical equation.
Magnesium Nitrate + 2 Hydrochloric acid >>>> 2 Nitric acid + Magnesium Chloride.
Mg(NO3)2 + 2HCl >> 2HNO3 + MgCl2.
200 g times 148 g/256 g.
= 115.6 grams Mg(NO3)2. In 250 ml.
115.6 divided by 148.32 g = 1.562 moles in 250 ml times 5 = 1.93 moles Nitric acid potential yield.
1.562 moles divide by 2 Mag Nitrate times 2 times 36.5 g = 57 g HCl.
The density of HCl: 1153 g per L times 0.250 g = 288.25 g HCl.
288.25 g -57 g = 231.25 g HCl left divided by 36.5 g = moles HCl.
HCl: 6.3 moles.
Nitric acid 1.93 moles and Hydrochloric 6.3 moles. The rest is salt (Magnesium Chloride) and water.
This is for 100 g. If you are using Sodium Nitrate you need to change the Ratio. Sodium Nitrate Atomic mass/Magnesium Nitrate Atomic mass times 0.756.
Step 2: Setup for Distillation and Sand Bath.
100 g of 100 percent Magnesium Nitrate or equiv salt (Nitrate).
250 ml of 31.45 percent -10 moles per L HCl.
1 L two flat bottom flask, thermometer joint sealed (with a hole to release gas) when heated.
Reflux distillation Condenser, tubing, and water for cooling.
50 g boiling glass 6 mm beads.
Sand (Quite pure) Check Amazon.com for that.
Note for the US you may be able depending on the state be able to buy Sodium Nitrate salt on Amazon.com. You may need a supplier for the Salt.
Here a video on Poorman Aqua Regas and Setting up Reflux.
Here the video on Distillation.
Note for Aqua Regas never use Grease it could cause a Fire. Use the HCl 10 Moles to seal the joints.
Add 100 g of Nitrate salt to a 1 L flask with 50 g of boiling chips. With the Hotplate and Ceramic bowl add 790 grams of Pure Sand as a good heat transfer medium. Never heat it without Sand and I do recommend using Veg Oil as an Oil bath due to the risk of Nitric acid fire or explosion.
Heat the solution for 1-2 hours and do this in a well-ventilated area due to HCl vapors. If you smell the vapors put on a gas mask and turn down the solution. When it Orange in color (Dissolved NO2 in water) your solution is done.
Step 3: Dissolving Different Metals in Aqua Regas.
I have tested the following metals (Brass, Iron, Silver 80 percent pure, Nickel, Antimony metal, and Cobalt metal) with this Aqua Regas (1.93 moles Nitric acid and 6 moles Hydrochloric acid).
Metals see above....
Here are some images and I will list the reactivity of each below.
Cobalt 99 percent Dissolved in completely in 4 hrs.
Iron 99 percent Dissolved completely in 5 hrs.
Copper brass coin Dissolved in 6 hrs.
Silver dissolved (80 percent, 20 percent copper) 0.5 g in 10 hrs.
Antimony 5 g half dissolved in 13 hrs.
Nickel sheets - the slowest may have a protective coating on it (still dissolving 24 hrs latter).
Step 4: Disposal of Salts.
Finally, I will discuss how to dispose of the salt.
Wearing PPE always with acids and bases to a 500 ml beaker add 50 ml waste acid and slowly acid sodium carbonate until it no longer fizzes! It may take 20-30 g of the base to neutralize the acid. This is 0.5 g of silver carbonate with some copper carbonate and nitrate salts.
For the antimony, nickel, cobalt, etc the same will be done. DO NOT DUMP DISSOLVED AQUA REGAS METAL SOLUTION DOWN THE DRAIN! IT IS ILLEGAL.
Step 5: Discussions on Reactivity of Metal.
This was an interesting Project.
Cobalt, steel, and copper (brass) were the most reactive while Silver was in-between. Also Antimony metal is not very reactive so it not a big surprise that it only half dissolved.
A stronger reaction with 200 g of Magnesium Nitrate may have worked better but I only wanted to use 100 g to start with. A stronger Nitric acid may have not dissolved these metals as much. I had to sign to get the Nitrate salts a hazardous signature first.
That is safety here in Canada with any Nitrate salts.
Thank you for reading this Instructable.