[{"data":1,"prerenderedAt":73},["ShallowReactive",2],{"q-fire-112-1-fire-science-006":3},{"subject":4,"subjectSlug":5,"subjectKicker":6,"subjectShort":7,"question":8,"related":27,"sameNumber":52,"hasEssay":26},"火災學概要","fire-science","火災學 · Fire Science","火災學",{"id":9,"webId":10,"year":11,"session":12,"subject":4,"number":13,"stem":14,"options":15,"answer":20,"answerNote":21,"images":22,"imagesPending":23,"lawTimestamp":11,"explanation":24,"explanationDeep":25,"freq":12,"indexable":26},"fire-112-1-火災學概要-006","fire-112-1-fire-science-006",112,1,6,"在標準狀態下，下列氣體中何者之爆炸範圍最廣？",{"A":16,"B":17,"C":18,"D":19},"氮","甲烷","氨","氫","D",null,[],false,"本題考點：常見氣體的燃燒（爆炸）界限數值比較，以及氮氣屬不燃性氣體、不具爆炸界限的基本性質。\n【正解理由】依標準狀態下的燃燒界限數據，氫氣約為 4%～75%,界限跨距約 71 個百分點；甲烷約 5%～15%,跨距約 10 個百分點；氨約 15%～28%,跨距約 13 個百分點；氮氣本身不可燃，沒有爆炸界限可言。四個選項中界限跨距最大者為氫氣，故選 D。\n【逐項排除】\n(A) 氮：分子內為三鍵、鍵能高，與氧化合屬吸熱反應，是不燃性（惰性）氣體，不存在爆炸範圍，反而常用於稀釋氧濃度。\n(B) 甲烷：約 5%～15%,跨距約 10 個百分點，為天然氣主成分，其下限與跨距均小於氫氣。\n(C) 氨：約 15%～28%,跨距約 13 個百分點，下限高達 15%、最小引燃能量也大，危險度指標僅約 0.87。\n(D) 氫：約 4%～75%,跨距約 71 個百分點；分子量僅 2、擴散快、最小引燃能量約 0.02 mJ,界限上限可推到 75% 附近，為本題應選者。\n【記憶點】氫 4～75、甲烷 5～15、氨 15～28,氮不燃無界限；本題選項中只有氫的跨距達 70 以上。","燃燒界限（爆炸界限）是可燃氣體與空氣混合後仍能維持火焰傳播的濃度區間：低於下限燃料不足，高於上限氧氣不足，兩者之外都無法傳播火焰。界限寬窄取決於分子的反應活性、最小引燃能量與擴散速率。常考數值可整組記下：氫 4～75%、乙炔 2.5～100%、一氧化碳 12.5～74%、乙醚 1.9～48%、二硫化碳 1.3～50%、甲烷 5～15%、丙烷 2.1～9.5%、氨 15～28%。\n危險度指標 H＝（上限−下限）÷下限，可把界限寬窄化為單一數字：氫 (75−4)÷4≒17.8、甲烷 (15−5)÷5＝2、氨 (28−15)÷15≒0.87、乙炔 (100−2.5)÷2.5＝39。由此可見乙炔在常見氣體中此值最大，氫次之；氨因下限高達 15%,此值不到 1。\n影響界限的因素也是常考點：溫度升高會使下限略降、上限上移，界限範圍擴大；摻入氮、二氧化碳等惰性氣體會使上限下移、下限微升，兩線交會之處即對應最小氧濃度（MOC）,低於該氧濃度時任何燃料濃度都不燃；以純氧取代空氣時下限幾乎不變，上限則大幅上移（甲烷在純氧中上限可達 60% 以上）。混合可燃氣體的下限以勒沙特列公式 100÷LFL＝Σ（Ci÷LFLi）計算。\n氮在火災學中的角色恰好相反：它是惰化與封入用氣體，靠稀釋氧濃度到最小氧濃度以下抑制燃燒，本身沒有燃燒界限；助燃性氣體（氧、氯、氟、一氧化二氮）同樣不燃卻供氧，兩者不可混為一談。相關考點還包括由下限推算最小氧濃度、由飽和蒸氣壓推算液體閃火點對應的蒸氣濃度，以及氨雖屬可燃氣體卻因下限高、引燃能量大而常被誤認為不燃的辨識題。",true,[28,32,36,40,44,48],{"webId":29,"stem":30,"number":31,"year":11,"session":12},"fire-112-1-fire-science-005","鄰二甲苯的閃火點為 157℃，若鄰二甲苯於 157℃時的飽和蒸氣壓為 2.0 mmHg，試求其燃燒下限為何？",5,{"webId":33,"stem":34,"number":35,"year":11,"session":12},"fire-112-1-fire-science-007","高壓氣體之爆炸界限，通常較常壓下為廣，下列何者氣體之爆炸界限，會呈現加壓時上、下限初呈狹窄，但繼續加壓後又變廣的現象？",7,{"webId":37,"stem":38,"number":39,"year":11,"session":12},"fire-112-1-fire-science-004","若空氣中的氧氣體積百分比為 21%，則甲烷完全燃燒的化學理論濃度為多少%？",4,{"webId":41,"stem":42,"number":43,"year":11,"session":12},"fire-112-1-fire-science-008","赤磷和黃磷分屬我國法定公共危險物品那一類？",8,{"webId":45,"stem":46,"number":47,"year":11,"session":12},"fire-112-1-fire-science-003","下列何者非為火災之特性？",3,{"webId":49,"stem":50,"number":51,"year":11,"session":12},"fire-112-1-fire-science-009","下列何者屬於我國法定公共危險物品中的易燃固體？",9,[53,57,61,65,69],{"webId":54,"year":55,"stem":56,"number":13},"fire-114-1-fire-science-006",114,"依據我國公共危險物品之分類，下列有關可燃液體與易燃液體之敘述，何者正確？",{"webId":58,"year":59,"stem":60,"number":13},"fire-113-1-fire-science-006",113,"有關防止靜電災害的方法，下列敘述何者正確？",{"webId":62,"year":63,"stem":64,"number":13},"fire-111-1-fire-science-006",111,"火災成長歷程中，下列何者非閃燃之現象？",{"webId":66,"year":67,"stem":68,"number":13},"fire-110-1-fire-science-006",110,"阿里山發生森林火災，已知火災當天的相對濕度為 60.0%，前一天相對濕度為 50.0%，再前一天相對濕度為 40.0%，試求火災當天的實效濕度？",{"webId":70,"year":71,"stem":72,"number":13},"fire-109-1-fire-science-006",109,"某次閃電的過程中，雲的底部和地面之間，電壓高達 1 千萬伏特，並在約 0.02 秒內輸送 20 庫倫的電量至地面。下列與閃電有關的敘述何者正確？",1785129966442]