(a) Henry’s Law states that, “the partial pressure of the gas in vapour phase (p) is proportional to the mole fraction of the gas (x) in the solution” and is given by the equation p = KHx, where KH is the Henry Law’s constant.
(i) The bends is a condition which occurs with scuba divers due to changes in pressure underwater. An increase in pressure increases solubility of gases in blood. Scuba divers have to breathe air under high pressures underwater in the presence of high concentrations of dissolved gases. The major gases present in the atmosphere are N2 and O2. These gases are not very soluble at normal pressures, however, underwater at high pressure, they dissolve in the blood. Once the divers come up to the surface, the gases escape the blood by forming bubbles of N2 in blood. These bubbles can block capillaries and obstruct the flow of O2, which forms the painful condition of bends.
(ii) At higher altitudes, atmospheric pressure is low and it reduces the solubility of oxygen in blood and tissues of people traveling or living at high altitudes. The lack of oxygen causes weakness and unable to think properly, a condition known as anoxia.
(b) Soda water and soft drinks are produced by adding CO2 to the liquid and sealing the bottles under high pressure, in order to increase the solubility of CO2. When a soda water bottle is opened at room temperature and normal pressure conditions, the pressure inside the bottle reduces and solubility of CO2 reduces, thus causing the gas bubbles to escape and soda water fizzing.
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