A typical coal-fired electric generating plant will burn about 3 metric tons of coal per hour. Most of the coal burned in the United States contains 1 to 4 % by weight sulfur in the form of pyrite, which is oxidized as the coal burns: 4FeS2(s) 11 O2(g) 2 Fe2O3(s) 8 SO2(g) Once in the atmosphere, the SO2 is oxidized to SO3, which then reacts with water in the atmosphere to form sulfuric acid: SO3(g) H2O(l) H2SO4(aq) If 61.7 metric tons of coal that contains 1.20 % by weight S is burned and all of the sulfuric acid that is formed rains down into a pond of dimensions 397 m x 258 m x 5.64 m, what is the pH of the pond

the pH of the pond is 4.0963

Explanation:

 Given the data in the question;

4FeS₂(s) + 11O₂(g)  >  2Fe₂O₃(s) + 8SO₂(g)

and oxidation of sulfur dioxide to trioxide

SO₃(g) + H₂O(l)  > H₂SO₄(aq)

given that; coal = 61.7 metric tons = 61700 kg

1.20 % by weight S, therefore mass of sulfur in coal will be;

⇒ 61700 × 1.20% = 740.4 kg

moles of sulfur = (740.4 × 1000 g) / 32 g/mole = 23,137.5 moles

moles of so₂ produced

= same moles of so₃ and same moles of H₂SO₄ = 23,137.5 moles

volume of pond = 397 m x 258 m x 5.64 m = 577,682.64 m³ = 577682640 L

Molarity = moles / volume = 23,137.5 / 577682640 = 4.0052 × 10⁻⁵ M

now each mole of  H₂SO₄ will give 2 moles of H⁺

[H⁺] = 2 × 4.0052 × 10⁻⁵ =  8.0104 × 10⁻⁵ M

pH = -log[H⁺]  

pH = -log [ 8.0104 × 10⁻⁵ M ]

pH = 4.0963

Therefore, the pH of the pond is 4.0963