Answer:
7.40×10²² molecules.
Step-by-step explanation:
From the question given above, the following data were obtained:
Volume of oxygen = 2.75 L
Number of molecules of oxygen =?
Next, we shall determine the number of mole of oxygen present. This can be obtained as follow:
22.4 L contains 1 mole of oxygen at STP.
Therefore, 2.75 L will contain = 2.75 / 22.4 = 0.123 mole of oxygen at STP.
Finally, we shall determine the number of molecules of oxygen present. This can be obtained as follow:
From Avogadro's hypothesis:
1 mole of oxygen = 6.02×10²³ molecules
Therefore,
0.123 mole of oxygen = 0.123 × 6.02×10²³
0.123 mole of oxygen = 7.40×10²² molecules.
Thus, the cylinder contains 7.40×10²² molecules of oxygen.