Stoichiometry RedOx Reaction

Shing Hin

2012-03-31 6:13 pm

1. Oxalic acid, H2C2O4, reacts with dichromate ion, in acidic solution to produce carbon dioxide and chromium(III) ion.
If exactly 50.0 mL of an oxalic acid solution is required to react completely with 85.0 mL of a 0.0450 M dichromate solution, what is the molarity of the oxalic acid solution?

2. Thiosulfate ion, S2O32-, reacts with iodine in acidic solution to produce tetrathionate ion, S4O62-, and iodide ion .
If exactly 50.0 mL of S2O32- solution is required to react completely with 45.0 mL of 7.50×10-4 M I2 solution, what is the molarity of the S2O32- solution?

回答 (1)

[匿名]

2012-03-31 7:23 pm

✔ 最佳答案

1.
3H2C2O4(aq) + Cr2O7²⁻(aq) + 8H⁺(aq) → 2Cr³⁺(aq) + 6CO2(aq) + 7H2O(l)

No. of moles of Cr2O7²⁻ = 0.0450 x (85.0/1000) = 0.00383mol
No. of moles of H2C2O4 = 0.00383 x 3 = 0.0115mol
Molarity of H2C2O4 = 0.0115/(50.0/1000) = 0.230 M

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2.
2S2O3²⁻(aq) + I2(aq)→ S4O6²⁻(aq) + 2I⁻(aq)

No. of moles of I2= (7.5 x 10⁻⁴) x (45/1000) = 3.375 x 10⁻⁵ mol
No. of moles of S2O3²⁻ = (3.375 x 10⁻⁵) x 2 = 6.75 x 10⁻⁵ mol
Molarity of S2O3²⁻ = (6.75 x 10⁻⁵)/(50/1000) = 1.35 x 10⁻³ M

參考: Adam

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