Potassium nitrate (salpeter) is a chemical commonly used in science experiments, plant fertilizers, and gunpowder because it is an ionic salt. In the past, people collected guano (bat droppings) in caves as the main ingredient for making potassium nitrate. At this point, you can easily make one if you have experience with chemicals. To make this versatile ingredient, you'll need a cold pack, potassium hydroxide, and water. With the time and proper precautions, you can safely make potassium nitrate.
Step
Part 1 of 3: Making Ammonium Nitrate Solution
Step 1. Purchase a cold pack containing ammonium nitrate
Ammonium nitrate is the active ingredient in most cold packs and is essential in the manufacture of potassium nitrate. Use a cold pack with the main active ingredient ammonium nitrate.
- If one cold pack is not enough to meet the needs of ammonium nitrate, buy another cold pack as needed.
- Cold packs containing ammonium nitrate can be found at drug stores or pharmacies. You can also buy pure ammonium nitrate online or at a lab supply store.
Step 2. Put on goggles, rubber gloves, and a gas mask
The manufacture of potassium nitrate requires you to handle several substances that can irritate the lungs, eyes, and skin. To prevent anything untoward from happening when making it, wear protective goggles, a gas mask, and thick rubber gloves.
Step 3. Open the cold pack and pour 80 ml of ammonium nitrate
Cut the top of the cold pack lengthwise using scissors. Pour the contents into a large measuring bowl marked in millimeters.
You can use a sharp knife if you don't have scissors
Step 4. Add 70 ml of hot water and stir the mixture
Measure out 70 ml of hot water-hot enough that you can feel the temperature, but not boiling or near boiling. Add the hot water to the ammonium nitrate and mix thoroughly.
- Pour slowly so that the solution does not splash and cause unwanted irritation to the skin.
- Keep stirring the mixture until the ammonium nitrate is completely dissolved in the hot water.
Step 5. Purify the ammonium nitrate with coffee filter paper
Some cold packs use a mixture of ammonium nitrate and other chemicals that can dilute the final product. You can prevent this by placing coffee filter paper in another measuring bowl and slowly pouring the ammonium nitrate solution over it.
When you're done, throw away the coffee filter immediately to prevent it from contaminating your purified solution
Part 2 of 3: Mixing Ammonium Nitrate with Potassium Hydroxide
Step 1. Pour 55 grams of potassium hydroxide into a measuring bowl
Potassium hydroxide is the second main ingredient in the manufacture of potassium nitrate. First, weigh the clear measuring bowl using the " tare " function (returns the scale number to "zero" after placing the container on it) to make it easier for you to measure. Next, pour 55 grams of potassium hydroxide into a bowl and make sure you put it in the right amount.
Dry potassium hydroxide can be found at chemical or hardware stores
Step 2. Add 1 tablespoon of water little by little to dissolve the potassium hydroxide
When preparing a potassium hydroxide solution, dissolve the dry ingredients by adding enough water. Pour 1 tbsp. (15 ml) of water at a time, mix thoroughly, and add more water if the potassium hydroxide is still dry.
You should make potassium hydroxide that is smooth and thick, like soup or pudding
Step 3. Mix ammonium nitrate and potassium hydroxide outdoors
This mixing process can produce toxic ammonium gas. In addition to wearing a gas mask with a dual filter, make this mixture outdoors to prevent ammonium gas poisoning.
If you are doing this in a laboratory, mix these chemicals in a fume hood
Step 4. Mix the two solutions slowly
If you have chosen a well-ventilated outdoor location, slowly pour the potassium hydroxide solution over the ammonium nitrate. When doing this, make sure you wear a safe gas mask to prevent irritation or serious injury from ammonium gas.
Part 3 of 3: Refining Potassium Nitrate
Step 1. Boil the solution using an outdoor stove
Pour the solution into a saucepan and place it on the stove for the outdoors. Use medium heat to simmer the solution for about 20 to 30 minutes, or until a ring of crystals forms on the outside.
- Continue to wear the gas mask while you boil it as the solution will continue to emit toxic ammonium gas.
- Pots that have been used to boil ammonium nitrate should not be used for cooking.
Step 2. Allow the ammonium nitrate to evaporate outdoors for about 1 to 2 weeks
Put the boiled solution in a measuring bowl, then place it on a flat surface at least 30 m away from the building or house. Allow the ammonium nitrate to evaporate for 2 weeks, or until white crystals remain in the bowl.
- Always wear a gas mask when handling liquid ammonium nitrate, and take care that no people or animals (especially children or pets) come near while the solution is evaporating.
- If the ammonium nitrate has evaporated and turned into a solid crystal, it will not emit ammonium gas anymore.
Step 3. Perform a test to see if the potassium nitrate reacts
To see if you really have pure potassium nitrate crystals, mix a small amount of the crystals with an equal amount of granulated sugar. Use a match to burn the mixture in a controlled area (eg in a laboratory). If the potassium nitrate is completely pure, the resulting flame will be purple.
Handle matches and potassium nitrate with care, and do this in a controlled area to avoid any untoward events
Tips
- Do it slowly so you can measure the ingredients just right, and handle chemicals with care.
- If you want, you can buy ready-made potassium nitrate online or at a lab supply store.
Warning
- Do not try to make potassium nitrate if you are not experienced with chemicals. This is to ensure that you are able to take proper precautions. Alternatively, you can buy potassium nitrate at a chemical store.
- The chemicals used in the manufacture of potassium nitrate can damage bare skin. Wear rubber gloves and protective eyewear while you complete the process to prevent skin irritation and other injuries.
- Always wear a gas mask when you mix and purify potassium nitrate to prevent injury from ammonium gas. Never mix ammonium nitrate and potassium hydroxide indoors.
