In order to determine the rate of photosynthesis (the conversion by plants of carbon dioxide and water into glucose and oxygen), the oxygen gas emitted by an aquatic plant is collected over water at a temperature of 293 K and a total pressure of 755.2 mmHg. Over a specific time period, a total of 1.02 L of gas is collected.

What mass of oxygen gas (in grams) forms?

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SORT The problem gives the volume of gas collected over water as well as the temperature and the pressure. You are to find the mass in grams of oxygen that forms. STRATEGIZE You can determine the mass of oxygen from the amount of oxygen in moles, which you can calculate from the ideal gas law if you know the partial pressure of oxygen. Since the oxygen is mixed with water vapor, you find the partial pressure of oxygen in the mixture by subtracting the partial pressure of water at 293 K (20 °C) from the total pressure. Next, use the ideal gas law to determine the number of moles of oxygen from its partial pressure, volume, and temperature. Finally, use the molar mass of oxygen to convert the number of moles to grams. GIVEN: V = 1.02 L, Ptotal = 755.2 mmHg, T = 293 K FIND: g 0₂ CONCEPTUAL PLAN Po₂ Ptotal-PH₂0(20 °C) Po₂, V, T 110₂ Po,V=no,RT 32.00 g 0₂ mol O₂ no₂ g 0₂ RELATIONSHIPS USED Ptotal=Pa+ R + P +... (Dalton's law) PV = nRT (ideal gas law)