Answer:
Sulfurous acid is formed by the reaction of water and sulfur dioxide.
Balanced reaction will provide the basic information.
Balanced Reaction :
SO₂ + H₂O -----------> H₂SO₃
1 mol 1mol 1mol
From above reaction we come to know
1 mole of H₂O ≅ 1 mole H₂SO₃
if 1 mole of H₂O produces 1 mole of H₂SO₃ then
0.680 mole of water will be required to produces sulfurous acid
Explanation through calculation
apply the unity formula
1 mole of the H₂O ≅ 1 mole of H₂SO₃
x mole of the H₂O ≅ 0.680 moles of H₂SO₃
so by cross multiplication
1 mole x X mole ≅ 1 mole x 0.680 mole
we have to find moles of H₂O ....so by rearrangement of the above equation
X mole of H₂O = 1 mole x 0.680 mole
X mole of H₂O = 0.680 moles
Step-by-step explanation: