Harold Urey Experiment

Harold Urey - Experiment Harold Urey’s discovery of deuterium is perhaps his most revolutionary discovery. Not only did Urey receive a Nobel Prize for his work towards hydrogen-2, deuterium would go on to become invaluable both to chemists’ understanding of the elements, and the field of chemistry as a whole. Urey’s pursuit of deuterium began in 1931, after his interest was piqued by a scientific journal that discussed the supposed existence of the isotope. Using the Balmer series, which is the series of lines in the hydrogen atomic emission spectrum, Urey and a colleague by the name of George Murphy, calculated where hydrogen-2’s emission lines should be located. They determined that the isotope’s emission lines would be “redshifted” (shifted

Instead using the Debye model, the two chemists determined that the heavy isotope should have a higher boiling point than elemental hydrogen. In theory, they determined that if five liters of the element was distilled into one milliliter, the sample would become enriched in hydrogen-2 by a hundred to two-hundred times. Seeing this as the perfect solution to their issue, Urey and Murphy journeyed to the National Bureau of Standards in Washington, D.C.; the cryogenics laboratory that was located there would allow them to obtain the amount of liquid hydrogen they needed to conduct the experiment. While in Washington, D.C., the men gained the help of Ferdinand Brickwedde, an old friend of Urey’s, who supplied them with the samples of liquid hydrogen. “Accordingly two samples of hydrogen were prepared by evaporating large quantities of liquid hydrogen and collecting the gas which evaporated…” (Urey, H., Brickwedde, F. G., and Murphy, G. M., 1932), and then analyzed by the chemists, whom were searching for evidence of deuterium. The initial sample was not successful at proving deuterium’s existence; it was evaporated at -423.7°F (20 K or -253.2 °C), at a pressure of one standard atmosphere (100 kPa), and showed no enrichment of hydrogen-2 whatsoever. The second sample, however, was successful. It was evaporated at −434.5 °F (14 K or (−259.1 °C), at a pressure of 53 mmHg (7.1