濃縮されたHCl溶液における急速な構造ダイナミクス:プロトンジャンプから大量粘度まで
Laura Kacenauskaite1,2, Max Moncada Cohen1, Stephen J Van Wyck1
1Department of Chemistry, Stanford University, Stanford, California 94305, United States.
Journal of the American Chemical Society
|April 29, 2024
まとめ
濃縮されたHCl溶液は独特の構造動態を示し,陽子のジャンプと大量粘度を最も遅いリラックス時間 (t3) と結びつける. この最もゆっくりとした動的成分は,純粋な水とは異なり,濃度とともに増加します.
科学分野:
- 物理化学
- ソリューションダイナミクス
- スペクトロスコーピー
背景:
- 濃縮したHClにおけるプロトンホッピングと水素イオンスペクトロスコピーはよく研究されている.
- 濃縮されたHCl溶液の構造的動態は,まだ理解されていない.
- HClとNaClの溶液を比較すると,ヒドロニウムカチオンの役割が明らかになる.
研究 の 目的:
- 濃度に依存するHCl溶液の構造的動態を調査する.
- HClの動態を,光学ヘテロジン検知-光学ケル効果 (OHD-OKE) を使用してNaCl溶液と比較する.
- 観測されたダイナミクスをプロトンジャンプと質量の粘度に関連付けます.
主な方法:
- オプティカル・ヘテロダイン検知 - オプティカル・ケル効果 (OHD-OKE) 測定
- 0.8mから15.5mまでの濃度依存のダイナミクスの分析
- Ab initio MDシミュレーションと2D IR化学交換実験からの文献データとの比較
主要な成果:
- HClとNaClの溶液は,純粋な水におけるbipeponential decayとは異なり,triexponential OHD-OKE信号崩壊を示している.
- 最も遅い衰退定数 (t3) は,総粘度と線形相関する.
- 陽子のジャンプ時間は,最も遅い構造ダイナミクスのリラックス時間 (t3) と一致します.
結論:
- 水素/塩化物/水のクラスターの構造ダイナミクスは,陽子のジャンプと質量の粘性を支配する.
- 最も遅いリラクゼーション時間 (t3) は,HCl濃度とともに増加し,純粋な水では存在しない.
- HCl の最速の分解定数 (t1,t2) は,純粋な水の定数に似ており,濃度によってわずかに増加する.
関連する概念動画
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In a strong and weak acid mixture, the strong acid dissociates completely and becomes a source of almost all the hydronium ions present in the solution. In contrast, the weak acid shows...
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01:20Titration of a Weak Base with a Strong Acid
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01:23Titration of a Strong Acid with a Strong Base
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03:38Polyprotic Acids
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Polyprotic acids of the type H2M constitute two ionizable protons. As a result, on titration with a base, they exhibit two equivalence points in the titration curve. During titration, the species H2M, HM−, and M2− will be present in the solution at different points. The fractions of H2M, HM−, and M2− present at the various instances of the titration are denoted by α0, α1, and α2, respectively.
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A graph with the alpha values is plotted against the volume of...
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03:22Strong Acid and Base Solutions
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A strong acid is a compound that dissociates completely in an aqueous solution and produces a concentration of hydronium ions equal to the initial concentration of acid. For example, 0.20 M hydrobromic acid will dissociate completely in water and produces 0.20 M of hydronium ions and 0.20 M of bromide ions.
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