A sample of carbon monoxide gas was collected in a 2.0 L flask by displacing water at 28^$\circ$C and 810 mmHg. Calculate the number of CO molecules in the flask. The vapor pressure of water at 28^$\circ$C is 28.3 mmHg. A) 5.0 * 10²² B) 5.2 * 10²² C) 3.8 * 10²³ D) 5.4 * 10²³ E) 3.8 * 10²⁵

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Quizplus · Accepted Answer

The partial pressure of CO is 810 mmHg - 28.3 mmHg = 781.7 mmHg. The number of moles of CO is n = PV/RT = (781.7 mmHg * 2.0 L) / (62.36 L mmHg/mol K * 283 K) = 0.0409 mol. The number of molecules is N = n * N_A = 0.0409 mol * 6.022 * 10^23 molecules/mol = 2.46 * 10^22 molecules.

A Sample of Carbon Monoxide Gas Was Collected in a 2.0