British Sign Language Glossaries of Curriculum Terms

BSL Chemistry Glossary - Ostwald process - Definition

The Ostwald process is used in the manufacture of nitric acid. Farmers use a lot of fertilisers to help crops grow and to ensure they are healthy and for that they need nitrogen. The Ostwald process is used to create nitric acid that can then be converted into nitrates which are water soluble compounds which are then spread on crops to make them grow.

Let me explain to you how Nitric Acid is made on an industrial scale using the Ostwald process.

The process starts with air which is compressed and the O₂ (in the air) is then mixed with ammonia (NH₃). This mixture is then heated up to 800°C and passed through layers of platinum. Once this mixture passes through the platinum it no longer needs further heating because an exothermic reaction takes place which releases huge amounts of heat - this happens because the platinum acts as a catalyst which speeds up the rate of reaction and it leads to the formation of nitrogen monoxide. Next more oxygen (O₂) is added which reacts with the nitrogen monoxide to form nitrogen dioxide - NO₂. This brown gas is then cooled down and mixed with the O₂ in water which then leads to the formation of nitric acid.

This is the Ostwald process - the key thing to remember is that platinum is needed as a catalyst.