A sample of sulfur trioxide (SO3) weighs 5100 g. How many molecules are contained in this sample? Use 80.063gmol for the molar mass of SO3.

From Avogadro's hypothesis, we understood that 1 mole of any substance contains 6.02×10²³ molecules. This simply implies that

1 mole of SO₃ = 6.02×10²³ molecules.

Recall,

1 mole of SO₃ = 80.063 g

Thus,

80.063 g of SO₃ = 6.02×10²³ molecules

With the above information, we can obtain the number of molecules in 5100 g of SO₃. This can be obtained as follow:

80.063 g of SO₃ = 6.02×10²³ molecules

Therefore,

5100 g of SO₃  

Therefore, 5100 g of SO₃ contains 3.83×10²⁵ molecules

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