Last revised 15/04/2021

3.5 Industrial chemistry

Curriculum links

ACSSU178 Chemical reactions involve rearranging to form new substances; during a mass is not created or destroyed. KEY IDEAS • In chemical reactions, atoms are rearranged to form new substances; matter is not created or destroyed. • Energy changes occur during chemical reactions.

ACSHE158 Advances in scientific understanding often rely on developments in and technological advances are often linked to scientific discoveries.

ACSHE160 People use scientific knowledge to evaluate whether they accept claims, explanations or predictions, and advances in science can affect people’s lives, including generating new career opportunities.

ACSHE228 Values and needs of contemporary society can influence the focus of scientific research.

Lesson outcomes At the end of this activity students will be able to: • recognise many everyday substances are products of a chemical industry • evaluate information from secondary sources • recognise a ready supply of raw materials and safe efficient conditions are necessary to make a chemical manufacturing process economic. Equipment list Each GROUP will require:

• Science by Doing Student Digital Things to consider is a colourless poison gas which can cause wheezing and breathlessness. Ensure students do not smell contents. Integration of the digital resources into the lesson will stimulate interest: : a podcast covering the life and work of Haber (3’30”). Huge Canberra blaze now under control (1’40”): A video from Canberra Times of an industrial fire in Canberra. What is the Haber process?: This video (4’) clearly outlines the chemistry of the Haber process, including the conditions needed for optimal production of ammonia. The Haber-Bosch Process (5’ 12”): A presentation explaining why this process was the most important chemistry discovery in the last hundred years.

Chemical Reactions 1 Last revised 15/04/2021

Teacher content information: • Fritz Haber (1868 -1934) was a German chemist, best known for developing, along with , the Haber (or Haber-Bosch) process for making ammonia from (from the air) and (from water and/or ). The ammonia produced is converted into nitric and other nitrogen compounds and is the source of most of the nitrogen found in synthetic chemicals including fertilisers, nylon and such as TNT and nitroglycerine. The Haber process was developed in the first decade of the twentieth century and came at a critical time for Germany, because World War One was about to break out. Before this, for making explosives was made from nitrate salts imported from Chile. The British Navy could easily blockade the import of nitrates to Germany. Without nitrates, Germany would have been unable to make explosives and the war would almost certainly have been shorter. The raw materials for the Haber process are available everywhere, enabling Germany to cease reliance on imported nitrates. Haber had another effect on the First World War. He was a patriotic German and used his chemical skills to help the war effort by organising the use of the poison gas , which was first used by the Germans at the battle of Ypres in Belgium in 1915. It was released from cylinders and carried by the wind towards the Allied trenches. The western allies were not prepared for the use of poison gas by the Germans and had no gas masks or other precautions in place. Ironically for one who had worked so hard for Germany, Haber had to flee his native land in 1933 because of his Jewish ancestry. He was awarded the for Chemistry in 1918 for his work on the Haber process. The Haber process: The raw materials required for the Haber process are readily available. In Australia, hydrogen is either obtained by of water or from the reaction between natural gas and steam. Nitrogen is extracted from liquid air by distillation. Air is cooled to -190°C, so that nitrogen (bp -196°C) is still a gas while (bp - 183°C) is a liquid, so can be removed. The equation for the synthesis of ammonia is:

N2 (g) + 3H2 (g)  2NH3 (g)

The reversible reaction is exothermic in the forward direction and so the production of ammonia is favored by lower temperatures. However the rate of the reaction is increased at high temperatures (particles have greater kinetic energy for effective collisions) and so a compromise temperature of about 450°C is used. Similarly, a compromise is made with the conditions of . The reaction occurs faster at high , but this increases both danger and the cost of production, so a pressure of about 200 atmospheres is used. An catalyst is also used to speed up the . The unused hydrogen (bp -273°C) and nitrogen (bp -196°C) in the reaction chamber can be recycled as gases, while the cooling process causes ammonia (bp -33°C) to liquefy and be collected. The industrial process therefore requires careful control of conditions, including supply of nitrogen and hydrogen and removal of ammonia, to maintain optimal conditions and ensure the plant functions safely and economically.

Chemical Reactions 2 Last revised 15/04/2021

Lesson plan Step 1: Introductory brainstorm about chemical products we use and industrial production. Step 2: Outline the Haber process as an example of an industrial process involving chemistry, emphasising its importance. The video clip and song are useful stimulus here, as well as the Science by Doing Student Guide diagram and information. Students write a descriptive paragraph about the Haber process, as outlined in the guide. Step 3: Students consolidate their understanding of the chemistry of the Haber process and its historical significance by exploring the Science by Doing Student Digital and completing Notebook questions. Suggested questions: 1. Do we need chemicals produced by industry? 2. Are any essential? Which can we live without? 3. Why is it important to understand the energy changes in industrial chemical reactions? 4. Why do you think increasing temperature makes some chemical reactions faster? 5. What factors must you consider to ensure a chemical plant runs economically? Follow up: Activity 4.8 deals with career paths in chemical engineering and industrial chemistry.

Chemical Reactions 3