Higher Tier: 水素燃料電池の半反応式を組み合わせよ
導入済み| English | 意味 |
|---|---|
| fuel-cell anode/ˈfjuːəl sel ˈænəʊd/ | 燃料電池の陽極 |
| fuel-cell cathode/ˈfjuːəl sel ˈkæθəʊd/ | 燃料電池の陰極 |
What would explain this observation?
- Higher Tier: A hydrogen fuel cell separates oxidation and reduction at two electrodes. The same number of electrons must be released at one electrode and accepted at the other.
- Start with a prediction. State the quantities or features you would compare, then decide what evidence could distinguish two explanations.
Build the model
- For the explicitly acidic-electrolyte model, hydrogen oxidation is 2H₂ → 4H⁺ + 4e⁻. Oxygen reduction is O₂ + 4H⁺ + 4e⁻ → 2H₂O. Adding the half equations cancels four hydrogen ions and four electrons, leaving 2H₂ + O₂ → 2H₂O. Oxidation means electron loss and reduction electron gain. These half equations are the embedded Higher-only part of the source section.
- fuel-cell anode 燃料电池阳极: The electrode where hydrogen oxidation releases electrons in the stated generating cell; fuel-cell cathode 燃料电池阴极: The electrode where oxygen reduction accepts electrons in the stated generating cell.
酸性の水素半反応式のうち、酸化を示すものはどれか。
難易度 1/5 · 100 コイン + 今日初回完了時に小ボーナス付与
酸化は電子を失うため、水素の半反応式は H2 -> 2H+ + 2e- となります。原子数（2:2）と電荷（0 両辺とも）が釣り合っています。左側に電子がある場合、それは還元を表し、酸素だけでは水素種なしに水は生成できません。
各専門用語を正確な意味と対応させよ。
難易度 2/5 · 140 コイン + 今日初回完了時に小ボーナス付与
関連する物理量やプロセスを区別するために定義を使用せよ。
Choose evidence that can test it
- Check atoms and charges separately. The hydrogen half equation has four hydrogen atoms on each side and zero net charge because +4 from H⁺ balances −4 from electrons. The oxygen half equation has two oxygen atoms and four hydrogen atoms on each side, again zero net charge. In this generating cell electrons leave the hydrogen anode through the external circuit and reach the oxygen cathode. The anode is negative and the cathode positive while the cell supplies electricity.
- Begin with one consistent electrolyte model. Balance hydrogen with H⁺, oxygen with water and charge with electrons, then scale to equal electron numbers and cancel. Do not mix an acidic half equation with an alkaline one containing OH⁻. The electrode names identify oxidation at the anode and reduction at the cathode; signs must be interpreted for a generating fuel cell, rather than copied from an externally powered electrolytic cell.
この場合、調査やモデルをより妥当にする2つの習慣は何か。
難易度 2/5 · 140 コイン + 今日初回完了時に小ボーナス付与
条件や仮定を明記することで他者が正確に再現でき、根拠となる証拠を記録することで結論を検証できます。相反する結果を隠すと、誤った結論を疑う証拠を失いますし、単一の測定でより広い主張を成立させることはできません。
Work from known quantities
- State the known values and their units. Choose the relation because its assumptions fit this case, then rearrange before substitution.
- Known: starting from H₂ → 2H⁺ + 2e⁻, multiply by two to match the four electrons consumed by O₂ + 4H⁺ + 4e⁻ → 2H₂O. Two represented H₂ molecules supply four electrons and one O₂ molecule accepts four. If three O₂ molecules react in the same scaled model, twelve electrons pass through the external circuit and six H₂O molecules form. Electrons cancel from the overall equation.
Each represented H₂ molecule releases two electrons in the stated half equation. How many are released by eight H₂ molecules? Use the same sequence: known quantities → model → relation → substitution → unit and interpretation.
上記の半反応式において、各 H₂ 分子は2個の電子を放出します。8個の H₂ 分子から放出される電子の総数は幾つですか？
難易度 2/5 · 140 コイン + 今日初回完了時に小ボーナス付与
結果は16 個の電子です。既知：各H2 は半反応式で2 個の電子を放出します。H2 分子が8個の場合：8 x 2 = 16 個の電子が放出され、外部回路を通じて酸素電極へ流れます。
Check the conclusion and its limits
- Do not put electrons on the reactant side for hydrogen oxidation, allow them to remain in the overall reaction, or say they pass through the electrolyte like they do through a metal wire. Common-tier students still need the overall reaction and fuel-cell evaluation, but these half equations and charge reasoning are Higher-only.
- Return to the original observation. Explain what the result supports, which conditions it assumes, and one way to test a competing explanation.
Electrons remain as a product of the complete balanced fuel-cell reaction. This claim is false: Electrons travel through the EXTERNAL circuit and cancel when the half equations combine: H2 releases exactly what O2 consumes. The overall reaction 2H2 + O2 -> 2H2O contains no electrons.
Higher Tier: combine hydrogen fuel-cell half equations: Check atoms and charges separately. The hydrogen half equation has four hydrogen atoms on each side and zero net charge because +4 from H⁺ balances −4 from electrons. The oxygen half equation has two oxygen atoms and four hydrogen atoms on each side, again zero net charge. In this generating cell electrons leave the hydrogen anode through the external circuit and reach the oxygen cathode. The anode is negative and the cathode positive while the cell supplies electricity.
完全な平衡燃料電池反応式の生成物として電子が残る。
難易度 1/5 · 100 コイン + 今日初回完了時に小ボーナス付与
電子は外部回路を移動し、半反応式が統合されることで打ち消し合います：H2 が放出するのは exactly O2 が消費する量です。全体反応2H2 + O2 -> 2H2O に電子は含まれません。
指定された発電セルにおいて水素の酸化により電子を放出する電極の技術用語を記せ。
難易度 1/5 · 100 コイン + 今日初回完了時に小ボーナス付与
燃料電池のアノードとは、指定された発電セルにおいて水素の酸化により電子を放出する電極のことである。