The percentage of sulfur in coal be determined by burning a sample of the solid and passing the resulting sulfur dioxide gas into a solutio?

[匿名]

2016-09-30 9:45 am

The percentage of sulfur in coal be determined by burning a sample of the solid and passing the resulting sulfur dioxide gas into a solution of hydrogen peroxide, which oxidizes it to sulfuric acid, and then titrating the acid. Calculate the mass percent of sulfur in a sample if the gas from an 8.05-g sample required 44.1 mL of 0.114 M NaOH in the titration of the diprotic acid.

回答 (1)

不用客氣

2016-09-30 10:41 am

✔ 最佳答案

Molar mass of S = 32. 06 g/mol

Series of reactions :
S + O₂ → SO₂ ...... [1]
SO₂ + H₂O₂ → H₂SO₄ ...... [2]
H₂SO₄ + 2NaOH → Na₂SO₄ + H₂O ...... [3]

Refer to reaction [3] :
Mole ratio H₂SO₄ : NaOH = 1 : 2
No. of moles of NaOH = (0.114 mol/L) × (44.1/1000 L)
No. of moles of H₂SO₄ = (0.114 mol/L) × (44.1/1000 L) × (1/2) = 0.00251 mol

Refer to reaction [2] :
Mole ratio SO₂ : H₂SO₄ = 1 : 1
No. of moles of SO₂ = No. of moles of H₂SO₄ = 0.00251 mol

Refer to reaction [1] :
Mole ratio S : SO₂ = 1 : 1
No. of moles of S = No. of moles of SO₂ = 0.002514 mol
Mass of S = (32.06 g/mol) × (0.002514 mol) = 0.0805 g

Mass % of S in the sample = (0.0805/8.05) × 100% = 1.00%

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