Ostwald process facts for kids

The Ostwald process is a clever chemical method used to make nitric acid. Nitric acid is a very important chemical, especially for creating the most common types of fertilizers that help plants grow. This process is named after Wilhelm Ostwald, a scientist who developed and patented it in 1902. It's also connected to another big chemical process called the Haber process, which makes ammonia – the starting material for the Ostwald process!

How Nitric Acid is Made

The Ostwald process turns ammonia into nitric acid in a few main steps. Think of it like a recipe with different stages.

Step 1: Ammonia to Nitric Oxide

First, ammonia gas (NH3) is mixed with oxygen gas (O2). This mixture is heated to a very high temperature, around 900 degrees Celsius. A special metal called platinum is used as a catalyst here. A catalyst is something that helps a chemical reaction happen faster without being used up itself.

In this step, the ammonia and oxygen react to form nitric oxide gas (NO) and water vapor (H2O). This reaction is called oxidation because the ammonia combines with oxygen.

• The chemical reaction looks like this:

4 NH3 (g) + 5 O2 (g) → 4 NO (g) + 6 H2O (g)

Step 2: Nitric Oxide to Nitrogen Dioxide

Next, the nitric oxide gas (NO) that was just made is cooled down a bit and then mixed with more oxygen. This causes another oxidation reaction. This time, the nitric oxide turns into a different gas called nitrogen dioxide (NO2). Nitrogen dioxide is a reddish-brown gas.

• The chemical reaction for this step is:

2 NO (g) + O2 (g) → 2 NO2 (g)

Step 3: Nitrogen Dioxide to Nitric Acid

Finally, the nitrogen dioxide gas (NO2) is dissolved in water (H2O). When nitrogen dioxide reacts with water, it forms dilute (meaning not very strong) nitric acid (HNO3). During this reaction, some of the nitrogen dioxide also changes back into nitric oxide, which can then be recycled back into the process.

• The main chemical reaction for making nitric acid is:

3 NO2 (g) + H2O (l) → 2 HNO3 (aq) + NO (g)

Sometimes, if there's extra oxygen present, the nitrogen dioxide can react with both oxygen and water to make even more nitric acid.

• Another way nitric acid can form:

4 NO2 (g) + O2 (g) + 2 H2O (l) → 4 HNO3 (aq)

After these steps, the dilute nitric acid can be concentrated to make it stronger for different uses, like making fertilizers or other chemicals.

See also

In Spanish: Método de Ostwald para niños