Question

How many molecules of sulfur trioxide are in 78.0 grams?

Answer 1

Molecular formula of sulfur trioxide is SO₃

Molar mass of SO₃ is -  32 + (16 x 3 ) = 80 g/mol

1 mol of any substance consists of 6.022 x 10²³ units. In 1 mol of SO₃ there are 6.022 x 10²³ molecules of SO₃

in 80 g of SO₃ - there are 6.022 x 10²³ molecules of SO₃

Therefore in 78 g of SO₃ - there are 6.022 x 10²³ /80 x 78 = 5.871 x 10²³ SO₃ ....

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