The SO2 present in air is mainly responsible for the phenomenon of acid rain. The
concentration of SO2 can be determined by titration against a permanganate solution of
known concentration as follows:
SO2 + MnO4^-1 -> SO4^-2 + Mn2+
(unbalanced)
Balance the equation showing all your working and calculate the mass of SO2 in asample of
air if 7.37mL of 0.008 M KMnO4 solution are required toreach the endpoint of the titration.
Balanced equation: 5SO2 + 2MnO4 +H2O ———-> 5SO4 +2Mn +4H
7.37 mL times 1 L/1000 mL times .008800 over 1L times 5 moles of so2 over 2 moles MnO4 times the molar mass of SO2 which is 64.063 g/1 mole SO2 = 0.00944 g SO2
Please
7.37 mL times 1 L/1000 mL times .008800 over 1L times 5 moles of so2 over 2 moles MnO4 times the molar mass of SO2 which is 64.063 g/1 mole SO2 = 0.00944 g SO2
To balance the equation SO2 + MnO4^-1 -> SO4^-2 + Mn2+, we start by writing down the chemical formulas of the reactants and products:
SO2 + MnO4^-1 -> SO4^-2 + Mn2+
Since the reaction takes place in an acidic medium, we can add H2O molecules and H+ ions to balance the equation:
SO2 + MnO4^-1 + H2O -> SO4^-2 + Mn2+ + H+
Next, to balance the oxygen atoms, we add H2O molecules to the left-hand side of the equation:
SO2 + MnO4^-1 + H2O -> SO4^-2 + Mn2+ + H2O
After balancing the oxygen atoms, we then balance the hydrogen atoms by adding the appropriate number of H+ ions:
SO2 + MnO4^-1 + 2H2O -> SO4^-2 + Mn2+ + 4H+
Finally, we add electrons (e^-) to balance the charge on each side of the equation:
SO2 + MnO4^-1 + 2H2O + 5e^- -> SO4^-2 + Mn2+ + 4H+
Now that the equation is balanced, we can use the stoichiometry of the reaction to calculate the mass of SO2 in the given sample of air. First, we need to convert the volume of KMnO4 solution used in the titration (7.37 mL) to moles by using the molarity (0.008 M) of KMnO4:
moles of KMnO4 = volume of KMnO4 solution (L) x molarity of KMnO4 (mol/L)
= 7.37 mL x 0.008 M / 1000 mL (conversion to L)
= 5.896 x 10^-5 mol
From the balanced equation, we can see that the stoichiometric ratio between KMnO4 and SO2 is 1:1. Therefore, the moles of KMnO4 used in the titration are equal to the moles of SO2 present in the air sample. Hence, the mass of SO2 can be calculated using its molar mass:
mass of SO2 = moles of SO2 x molar mass of SO2
= 5.896 x 10^-5 mol x 64.06 g/mol (molar mass of SO2)
= 0.003766 g
≈ 3.77 mg
Therefore, the mass of SO2 in the air sample is approximately 3.77 mg.