[{"data":1,"prerenderedAt":188},["ShallowReactive",2],{"topic-page:\u002Fhigh-school\u002Fbasic-chemistry\u002Facid-base-and-redox\u002Fhydrogen-ion-concentration-and-ph":3},{"topic":4,"category":152,"seo":157,"breadcrumbs":162,"prerequisites":169,"nextTopics":179,"relatedTopics":187},{"id":5,"slug":6,"title":7,"summary":8,"canonicalPath":9,"categoryPath":10,"difficulty":11,"targetAudience":12,"estimatedMinutes":13,"generatedAt":14,"publishedAt":14,"updatedAt":14,"reviewStatus":15,"tags":16,"expectedKnowledge":22,"learningGoal":26,"blocks":27},"high-school-basic-chemistry-acid-base-and-redox-hydrogen-ion-concentration-and-ph","hydrogen-ion-concentration-and-ph","水素イオン濃度とpH","水素イオン濃度とpHの対数関係を読み、25 ℃の水溶液という条件のもとで酸性・中性・塩基性を判断します。","\u002Fhigh-school\u002Fbasic-chemistry\u002Facid-base-and-redox\u002Fhydrogen-ion-concentration-and-ph","\u002Fhigh-school\u002Fbasic-chemistry\u002Facid-base-and-redox","beginner","student_high",6,"2026-07-28","ai_generated",[17,18,19,20,21],"化学基礎","pH","水素イオン濃度","常用対数","水の電離",[23,24,25],"モル濃度","指数と常用対数","強弱と濃淡","与えられた[H⁺]からpHを求め、10倍の濃度変化とpH1の変化を対応させ、25 ℃で液性を判断できるようになる。",[28,34,43,68,74,83,105,111,117,133,142],{"id":29,"type":30,"title":31,"subtitle":32,"shortDefinition":33},"hero","HeroBlock","pHは濃度を対数で縮めた目盛","1違うとH⁺濃度は10倍違う","pHは水素イオン濃度[H⁺]を常用対数で表した尺度です。25 ℃の水溶液ではpH 7を中性の基準とします。",{"id":35,"type":36,"term":18,"definition":37,"plainExplanation":38,"keywords":39},"definition","DefinitionBlock","水素イオン濃度[H⁺]をmol\u002FLで表し、その常用対数の符号を変えた値です。","[H⁺]=1.0×10⁻³ mol\u002FLならpH 3です。[H⁺]が10倍になるとpHは1小さくなります。小さいpHほどH⁺濃度が大きい点に注意します。25 ℃では水の電離により[H⁺]と[OH⁻]がともに1.0×10⁻⁷ mol\u002FLのとき中性で、pH 7です。",[40,41,42],"pH=-log[H⁺]","10倍で1変化","25 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3、4、5で[H⁺]が10分の1ずつになる関係を示します。酸性・中性・塩基性は文字と目盛でも区別します。",{"id":75,"type":76,"steps":77,"title":82},"steps","StepBlock",[78,79,80,81],"水溶液の温度条件と[H⁺]の単位mol\u002FLを確認する","[H⁺]をa×10の整数乗の形に整える","pH=-log₁₀[H⁺]へ代入する","25 ℃ならpH 7との大小で液性を判断し、濃度との逆向きを確認する","pHを求める手順",{"id":84,"type":85,"columns":86,"rows":88,"summary":104},"compare","CompareBlock",[87,55,18],"25 ℃での例",[89,93,96,100],[90,91,92],"酸性","1.0 × 10⁻³ mol\u002FL","3",[90,94,95],"1.0 × 10⁻⁵ mol\u002FL","5",[97,98,99],"中性","1.0 × 10⁻⁷ mol\u002FL","7",[101,102,103],"塩基性","1.0 × 10⁻⁹ mol\u002FL","9","pHが2増えると[H⁺]は100分の1になります。目盛は等間隔でも濃度差は等差ではありません。",{"id":106,"type":107,"scenario":108,"explanation":109,"result":110},"example","ExampleBlock","25 ℃で[H⁺]=2.0×10⁻³ mol\u002FLの水溶液のpHを求める。log₁₀2.0=0.301とする。","pH=-log₁₀(2.0×10⁻³)=-0.301+3=2.699です。与えられた有効数字に合わせてpH 2.70とします。1.0×10⁻³ mol\u002FLならpH 3なので、H⁺が2倍多いこの溶液のpHが3より小さいことも整合します。","pHは2.70で、25 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