Final answer:
PCl₃, a chemical compound, can affect the rate of loading and unloading of O₂ by reacting with water to form phosphorous acid.
Step-by-step explanation:
PCl₃, phosphorus trichloride, can affect the rate of loading and unloading of O₂. This is because PCl₃ reacts with water to yield hydrogen chloride and phosphorous acid. The presence of phosphorous acid affects the overall reaction rate and can alter the rate of oxygen loading and unloading.