[{"data":1,"prerenderedAt":73},["ShallowReactive",2],{"q-fire-113-1-fire-science-015":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-113-1-火災學概要-015","fire-113-1-fire-science-015",113,1,15,"有關天然氣與液化石油氣之比較，下列敘述何者錯誤？",{"A":16,"B":17,"C":18,"D":19},"天然氣的主成分為丙烷，液化石油氣主成分為甲烷","天然氣蒸氣密度較空氣輕，液化石油氣蒸氣密度較空氣重","天然氣與液化石油氣皆為無色無味","液化石油氣的燃燒熱比天然氣燃燒熱高","A",null,[],false,"本題考點：天然氣與液化石油氣在主成分、蒸氣密度、氣味與燃燒熱四項基本性質上的對照。\n【正解理由】天然氣的主成分是甲烷，液化石油氣的主成分是丙烷與丁烷。選項把兩者的主成分完全對調，與事實相反，故選 A。這組性質差異的源頭就是主成分：甲烷分子量 16，比空氣輕；丙烷分子量 44、丁烷 58，都比空氣重，後續的蒸氣密度與燃燒熱差異都由此而來。\n【逐項排除】\n(A) 敘述錯誤，為本題所選。天然氣主成分為甲烷、液化石油氣主成分為丙烷與丁烷，選項所述恰好顛倒。\n(B) 敘述正確。甲烷對空氣的蒸氣密度約 0.55，洩漏時往上蓄積於天花板附近；丙烷約 1.5，洩漏時沿地面流向低窪處。\n(C) 敘述正確。兩者本身皆為無色無味的氣體，供氣時另行添加硫醇類臭劑以利察覺洩漏。\n(D) 敘述正確。同溫同壓下相同體積即相同莫耳數，丙烷完全燃燒的燃燒熱約每莫耳 2,220 kJ，甲烷約每莫耳 890 kJ，液化石油氣明顯較高。\n【記憶點】天然氣是甲烷、輕、往上飄；液化石油氣是丙丁烷、重、沿地面積聚且體積燃燒熱較高。","天然氣與液化石油氣的差異都可由主成分一路推導。天然氣主成分甲烷，分子量 16，對空氣比重約 0.55，常壓沸點約攝氏負 162 度，因此需以深冷液化成為液化天然氣或直接以管線供氣；液化石油氣主成分為丙烷（分子量 44）與丁烷（分子量 58），對空氣比重約 1.5 至 2.0，常溫下加壓即可液化，故以鋼瓶供應。\n比重差異直接決定洩漏後的行為與偵測要領：天然氣洩漏後往上升並蓄積於天花板附近，瓦斯漏氣檢知器裝設於上方；液化石油氣比空氣重，會沿地面流動並積存於低窪處、地下室與排水溝，檢知器裝設於下方。這也是兩者在火災與爆炸時擴散範圍不同的根本原因。\n燃燒特性方面，丙烷完全燃燒的燃燒熱約每莫耳 2,220 kJ，甲烷約每莫耳 890 kJ；同溫同壓下相同體積即相同莫耳數，故液化石油氣的體積燃燒熱明顯較高，達到相同火力所需的氣量較少。但若改以每公斤計，甲烷反而略高於丙烷，題目一旦指明「單位質量」，方向就要調轉。爆炸界限方面，甲烷約 5% 至 15%，丙烷約 2.1% 至 9.5%，丁烷約 1.8% 至 8.4%，液化石油氣的爆炸下限較低，較少量洩漏即可能進入爆炸範圍。\n兩者本質上都是無色無味的氣體，為使人在濃度累積到危險程度前察覺，供氣時會添加硫醇類臭劑；這是外加的「加臭」而非氣體本身有味道，選項常拿這一點設計陷阱。完全燃燒反應式方面，甲烷為 CH₄＋2O₂→CO₂＋2H₂O，丙烷為 C₃H₈＋5O₂→3CO₂＋4H₂O，每莫耳所需氧氣分別為 2 莫耳與 5 莫耳，換算後丙烷的理論空氣量為甲烷的 2.5 倍，這也說明同體積的液化石油氣洩漏時所需的稀釋通風量更大。",true,[28,32,36,40,44,48],{"webId":29,"stem":30,"number":31,"year":11,"session":12},"fire-113-1-fire-science-014","下列何者屬水蒸氣爆炸？",14,{"webId":33,"stem":34,"number":35,"year":11,"session":12},"fire-113-1-fire-science-016","依國家標準 CNS15030「化學品分類及標示」規定混合物中含致癌物質超過 0.1%即屬致癌混合物。目前內政部消防署決議限制滅火器藥劑以下那一類物質含量不得超過 0.1%？",16,{"webId":37,"stem":38,"number":39,"year":11,"session":12},"fire-113-1-fire-science-013","標準狀態下，在一間長 8 公尺、寬 5 公尺、高 3 公尺的密閉空間內，請問要加入多少體積（立方公尺）的二氧化碳，才能使室內二氧化碳之體積濃度達到 30 %？",13,{"webId":41,"stem":42,"number":43,"year":11,"session":12},"fire-113-1-fire-science-017","建築火災中會被通風口的大小設計所影響，通風因子為下列何者？（A：通風口面積、W：通風口寬度、H：通風口高度）",17,{"webId":45,"stem":46,"number":47,"year":11,"session":12},"fire-113-1-fire-science-012","直徑一公尺的柴油儲罐因火災受熱溫度達到 727 度，其柴油輻射率為 0.99，波茲曼常數為 5.67×10 -11 (kW\u002Fm 2 K4 )，請問會產生多少的輻射熱（kW\u002Fm 2 ）？",12,{"webId":49,"stem":50,"number":51,"year":11,"session":12},"fire-113-1-fire-science-018","空氣中氧氣的體積含量約為 X%，當氧濃度下降至 Y%時，一般燃燒難以持續，則 X，Y 分別為多少？",18,[53,57,61,65,69],{"webId":54,"year":55,"stem":56,"number":13},"fire-112-1-fire-science-015",112,"在煙控系統設計中，兩開口面積均為 1.0 m2，相互串聯後，其等效流動面積為何？（ 2 = 1.414 ）",{"webId":58,"year":59,"stem":60,"number":13},"fire-111-1-fire-science-015",111,"下列發火源在理化現象歸類上，何者與其他不同類別？",{"webId":62,"year":63,"stem":64,"number":13},"fire-110-1-fire-science-015",110,"下列有關液化天然氣（LNG）與液化石油氣（LPG）之比較，何者正確？",{"webId":66,"year":67,"stem":68,"number":13},"fire-109-1-fire-science-015",109,"下列海龍替代滅火藥劑，何者之化學組成為五氟乙烷？",{"webId":70,"year":71,"stem":72,"number":13},"fire-108-1-fire-science-015",108,"下列何種現象對於局部電阻所產生的效應恰與其他三者相反？",1785129966265]