Calculate the mass of sulphur which when burned in excess oxygen produces 640g of sulphur dioxide.
Solid sulfur, when burned in presence of oxygen, generates sulfur dioxide, as per the following balanced chemical equation:
`S(s) + O_2 (g) -> SO_2 (g)`
Here, 1 mole of sulfur reacts with 1 mole of oxygen to produce 1 mole of sulfur dioxide.
The molar mass of sulfur is 32 g/mol, oxygen is 16 g/mol and sulfur dioxide is 64 g/mol.
640 g of sulfur dioxide is produced here, or 10 moles (= 640 g/(64 g/mol)) of sulfur dioxide has been produced here.
Using stoichiometry, 10 moles of solid sulfur are required to produced 10 moles of sulfur dioxide.
or, 320 g (= 10 moles x 32 g/mol) of solid sulfur are needed.
We can also write, 320 g of sulfur, when burned in excess oxygen, produces 640 g of sulfur dioxide.
Hope this helps.
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