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Dalton’s Law of Partial Pressure. Dalton’s Law. All gases behave pretty much the same. Observe more than one gas in a sample. If 2 or more gases are mixed in a container, each gas will exert a pressure PARTIAL PRESSURE Total pressure = sum of partial pressures. Dalton’s Law.
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Dalton’s Law • All gases behave pretty much the same. • Observe more than one gas in a sample. • If 2 or more gases are mixed in a container, each gas will exert a pressure PARTIAL PRESSURE • Total pressure = sum of partial pressures
Dalton’s Law • PTOT = PA + PB + PC • Patm = PO2 + PN2 + PCO2 + PAr
Dalton’s Law • A sample relationship exists between the total pressure and individual partial pressures MOLE FRACTION
Dalton’s Law Def: Mole Fraction = mols of one substance = X total moles (XA + XB +XC =1) Partial Pressure = pressure exerted by only one gas in a mixture. PA = nART/V or PA = XAPTOT
Dalton’s Law • Gases are often collected over water, hence the need for partial pressures. • PTOT = PGAS + PH20 VAPOR