hce_nthu
115年
化學與物理
第 27 題
Oil painting typically involves a variety of inorganic pigments. Studies have found that under different humidity and light conditions in air, the fading of the pigment orpiment ($\text{As}_2\text{S}_3$) is mainly due to the following two chemical reactions ($\text{I}$ and $\text{II}$):
Which of the following statements is correct?
Which of the following statements is correct?
- A The structures of $\text{S}_2\text{O}_3^{2-}$ and $\text{SO}_4^{2-}$ are both tetrahedral.
- B In both reactions $\text{I}$ and $\text{II}$, the elements As and S are oxidized.
- C In reactions $\text{I}$ and $\text{II}$, the amount of $\frac{n(\text{O}_2)}{n(\text{H}_2\text{O})}$ participating in the reaction satisfies: $\text{I} < \text{II}$.
- D In reactions $\text{I}$ and $\text{II}$, the ratio of the number of electrons transferred when $1 \text{ mole}$ of $\text{As}_2\text{S}_3$ is oxidized is $3:7$.
- E The energy required for reaction $\text{I}$ is lower than that for reaction $\text{II}$.
思路引導 VIP
在觀察這兩個反應路徑時，請先試著找出產物中砷（As）與硫（S）分別達到了什麼樣的氧化數（化合價）。比較一下反應 I 與反應 II，哪一個路徑讓這些元素「爬升」到了更高的氧化態？這對該反應路徑中每一莫耳原料所需要「搬運」的電子總數會產生什麼樣的比例影響呢？
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AI 詳解
AI 專屬家教
太棒了！你能準確選出選項 (D)，代表你對氧化還原反應的定量計算與氧化數判斷掌握得非常紮實，這在處理複雜的無機反應時是極為關鍵的能力。
氧化數與電子轉移的精準計算
這道題目的核心在於追蹤元素在不同反應路徑下的電子得失。在反應物雌黃 ($As_2S_3$) 中，砷 ($As$) 為 $+3$ 價，硫 ($S$) 為 $-2$ 價。我們來對比這兩條路徑：
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