Question

Calculate the number of molecules of sulfur dioxide gas released when 9.83 g of solid calcium sulfite is reacted with excess hydrobromic acid.

CaSO3 + 2 HBr --> SO2 + H2O + CaBr2

Answer 1

Mass of CaSO₃ = 9.83 g

moles of CaSO₃ = (mass of CaSO₃) / (molar mass of CaSO₃)

moles of CaSO₃ = (9.83 g) / (120.14 g/mol)

moles of CaSO₃ = 0.08182 mol

moles SO₂ formed = moles of CaSO₃ reacted

moles SO₂ formed = 0.08182 mol

molecules SO₂ released = (moles SO₂ formed) * (Avogadro's number)

molecules SO₂ released = (0.08182 mol) * (6.022 x 10²³ molecules/mol)

molecules SO₂ released = 4.93 x 10²² molecules