エネルギー移動：加熱および冷却について説明せよ
導入済み| English | 意味 |
|---|---|
| exothermic/eɡzəˈðɜːmɪk/ | 発熱 |
| endothermic/ˌendəʊˈθɜːmɪk/ | 吸熱 |
What would explain this observation?
- A hand warmer releases energy to your hands. An instant cold pack takes energy from its surroundings. The direction of energy transfer explains their different uses.
- Start with a prediction. State the quantities or features you would compare, then decide what evidence could distinguish two explanations.
Build the model
- Energy is conserved in chemical reactions. An exothermic 放热 reaction transfers energy to the surroundings, which become warmer; products have less energy than reactants by the amount transferred. Combustion, many oxidation reactions and neutralisation are exothermic examples. An endothermic 吸热 reaction takes energy from the surroundings, which cool; products have more energy than reactants. Thermal decomposition and citric acid reacting with sodium hydrogencarbonate are endothermic examples.
- exothermic: Transferring energy from reacting chemicals to the surroundings; endothermic: Taking energy from the surroundings into reacting chemicals.
外部冷却のない反応中に溶液が冷却される。どの説明が適切か？
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冷却とは混合物が反応に対してエネルギーを失ったことを意味します。吸熱反応は周囲からエネルギーを取り込むため、温度計の数値が下がります。エネルギーは移転され、破壊されることはありません。「消失する」という表現は保存則に反します。
各専門用語を正確な意味と対応させよ。
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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
- Distinguish the reacting chemicals from their surroundings. A thermometer in a reacting solution measures the temperature of that solution, which receives or supplies energy during the chemical change. A temperature rise supports an exothermic interpretation under the stated conditions; a fall supports endothermic behaviour. Heating a vessel externally can obscure this evidence. Not every process involving cooling is a chemical reaction: new substances must also be formed.
- Evaluate a supplied warmer or cold-pack design against its purpose: suitable temperature, duration, risk of leakage, storage and single-use waste. Use information supplied for the particular product. Many self-heating cans exploit exothermic changes; some sports injury packs use endothermic changes. These examples explain energy transfers and do not recommend applying an untested chemical mixture to skin.
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。
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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: a supervised reaction starts at 21.0 °C and reaches 28.5 °C. The temperature rise is 28.5−21.0=7.5 °C, supporting an exothermic interpretation with no external heater. A second starts at 22.0 °C and falls to 17.0 °C: the change is −5.0 °C and its cooling magnitude is 5.0 °C. Energy has been transferred, not destroyed.
A reaction starts at 19.5 °C and reaches 27.0 °C. Find the temperature rise. Use the same sequence: known quantities → model → relation → substitution → unit and interpretation.
反応が 19.5 °C で始まり 27.0 °C に達した。温度上昇を求める。
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 7.5 °C です。既知：開始 19.5 °C；ピーク 27.0 °C。温度上昇 = 27.0 − 19.5 = 7.5 °C。ヒーターなしでこの程度の上昇が見られれば、発熱反応を示唆します。
Check the conclusion and its limits
- AQA 4.5.1.1 requires measuring temperature changes, not calculating transferred energy using heat capacity or calculating molar enthalpy. Those quantities are not substitutes for the required temperature evidence. A warmer that becomes hotter is not necessarily more suitable if it can burn skin or runs out too quickly.
- Return to the original observation. Explain what the result supports, which conditions it assumes, and one way to test a competing explanation.
An exothermic reaction destroys energy as its surroundings warm. This claim is false: Exothermic reactions TRANSFER energy to the surroundings, which is why they warm. Energy is conserved in every process; it moves between the reaction mixture and its surroundings but is never destroyed.
Energy transfers: explain warming and cooling: Distinguish the reacting chemicals from their surroundings. A thermometer in a reacting solution measures the temperature of that solution, which receives or supplies energy during the chemical change. A temperature rise supports an exothermic interpretation under the stated conditions; a fall supports endothermic behaviour. Heating a vessel externally can obscure this evidence. Not every process involving cooling is a chemical reaction: new substances must also be formed.
発熱反応は周囲が暖まることでエネルギーを消失させる。
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発熱反応は周囲へエネルギーを移転するため、暖かくなります。あらゆる過程でエネルギーは保存され、反応混合物と周囲の間で移動しますが、破壊されることはありません。
反応する化学物質から周囲へエネルギーを移動させる：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
発熱反応とは、反応する化学物質から周囲へエネルギーを移動させることを意味する。