Highly reflective and resistant to corrosion, rhodium is the rarest and most valuable precious metal in the world. The main use for rhodium is in catalytic converters designed to clean vehicle emissions. Without rhodium catalysts, the air in our cities would be much worse due to vehicle exhausts. This Element of Surprise segment features the following experts: Cathleen Crudden, Canada Research Chair in chemistry, Queen's University, and Paul Johns, physics professor, Carleton University.

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