为什么起爆药一点就炸？
Why are primary explosives so sensitive?
起爆药（叠氮化铅、雷酸汞那一类）的设计目的不是「威力大」，而是被一点点刺激就启动: 分解的活化能低，微弱的热、摩擦或撞击就足以开始反应，而反应一旦开始就自加热、并自我加速，在毫秒级把固体变成大量气体。它自己炸不了多少东西，作用是提供那个起爆脉冲，去引爆下面那层敏感度低、威力大的炸药。也正因为敏感，起爆药必须单独存放，且严禁金属摩擦——实验室里它总是以少量、湿润或封装的形式出现。
Primary explosives (lead azide, mercury fulminate and the like) are designed not to be powerful but to be easy to start: the activation energy for decomposition is low, so slight heat, friction or impact begins the reaction, which then self-heats and accelerates, turning solid into a large volume of gas within milliseconds. They barely detonate anything by themselves; their job is to supply the initiating pulse for the less sensitive, more powerful charge beneath. That same sensitivity is why they are stored separately, never subject to metal friction, and appear in the lab in small, damp or encapsulated amounts.
难度 专业 · 适合 高中(15-18)
CC BY 4.0 · 已核验 · Verified 2026-08-23
来源 · Source
Brown, LeMay 等,《Chemistry: The Central Science》第14版,Pearson,2017
T. L. Brown et al., Chemistry: The Central Science, 14th ed., Pearson, 2017
#起爆药 #敏感 #引爆
蜡烛的火苗为什么总朝上?吹灭后的白烟为什么能点着?
Why do candle flames always point up — and why can smoke relight?
火焰是燃烧的热气体,热空气比冷空气轻,拼命往上蹿,火苗自然向上跳。刚吹灭时的白烟其实是蜡的蒸气还没散尽,用点着的火柴靠近烟(不是烛芯),火苗会顺着烟跑回去重新点燃蜡烛——这个小实验一定要请大人陪你做!
Flames are hot burning gas; hot air is lighter and races upward, so flames leap up. The white smoke after blowing out is wax vapor still escaping — touch a lit match to the smoke (not the wick) and fire runs down it to relight the candle. Always ask a grown-up to try this with you!
难度 进阶 · 适合 小学低段(6-8)
CC BY 4.0 · 已核验 · Verified 2026-10-03 · 2 条独立证据
来源 · Source
《十万个为什么》第六版化学分册,少年儿童出版社,2013
Ten Thousand Whys: Chemistry volume, 6th ed., Juvenile and Children Publishing House, 2013
独立核验依据 · Independent verification: 核验依据 1 ISBN 978-7-5324-9328-9 · 核验依据 2 ISBN 9787532493289
#蜡烛 #火焰方向 #蒸气复燃
为什么用火石敲一下会冒火星？
Why do sparks fly when we strike a flint?
硬石头互相撞会蹭出小热点，把掉下来的碎屑瞬间点着，就成了火星。这些火星其实是被摩擦烧红的小铁屑，凉了就变成黑黑的小点。
Hard stones hitting each other make hot spots that light tiny bits, shooting out sparks. The sparks are really tiny bits of metal heated red-hot by the friction, which cool into black specks.
难度 入门 · 适合 小学低段(6-8)
CC BY 4.0 · 已核验 · Verified 2026-08-23
来源 · Source
Brown, LeMay 等,《Chemistry: The Central Science》第14版,Pearson,2017
T. L. Brown et al., Chemistry: The Central Science, 14th ed., Pearson, 2017
#火石 #火星 #摩擦
纸为什么能烧着？
Why can paper catch fire?
纸主要是纤维素，遇火受热分解出可燃气体，与氧气反应放热，只要热量够就持续燃烧。
Paper is mostly cellulose; heat breaks it into flammable gases that react with oxygen and release heat, sustaining combustion once ignited.
难度 入门 · 适合 幼儿(3-6)
CC BY 4.0 · 已核验 · Verified 2026-08-23
来源 · Source
Brown, LeMay 等,《Chemistry: The Central Science》第14版,Pearson,2017
T. L. Brown et al., Chemistry: The Central Science, 14th ed., Pearson, 2017
#纸 #纤维素 #燃烧
为什么木头能在火里烧成灰？
Why does wood burn to ash in a fire?
木头里主要是碳和氢，碰到火里的氧就燃烧，变成二氧化碳和水跑掉。烧不完的是木头里的矿物质，它们留下来变成了灰。
Wood is mostly carbon and hydrogen, which burn with oxygen to form carbon dioxide and water that escape. What will not burn is the minerals in the wood, and those leftovers are the ash.
难度 入门 · 适合 小学高段(9-12)
CC BY 4.0 · 已核验 · Verified 2026-08-23
来源 · Source
Brown, LeMay 等,《Chemistry: The Central Science》第14版,Pearson,2017
T. L. Brown et al., Chemistry: The Central Science, 14th ed., Pearson, 2017
#木头 #燃烧 #灰
为什么用水能浇灭小火？
Why can water put out a small fire?
水一浇上去又降温又把火和空气隔开，火就灭了。
Water cools the fire and blocks air from it, so the flames stop.
难度 入门 · 适合 幼儿(3-6)
CC BY 4.0 · 已核验 · Verified 2026-08-23
来源 · Source
Brown, LeMay 等,《Chemistry: The Central Science》第14版,Pearson,2017
T. L. Brown et al., Chemistry: The Central Science, 14th ed., Pearson, 2017
#水 #灭火 #火
灭火的原理是什么？
What is the principle behind putting out a fire?
燃烧需要燃料、氧气和达到着火点的温度三者同时存在；去掉任意一个，比如用水降温或用盖子隔绝氧气，就能灭火。
Fire needs fuel, oxygen and heat together; removing any one—cooling with water or smothering with a lid—stops combustion.
难度 入门 · 适合 幼儿(3-6)
CC BY 4.0 · 已核验 · Verified 2026-08-23
来源 · Source
Brown, LeMay 等,《Chemistry: The Central Science》第14版,Pearson,2017
T. L. Brown et al., Chemistry: The Central Science, 14th ed., Pearson, 2017
#燃烧 #灭火 #氧气
为什么划火柴会冒出小火苗？
Why does striking a match make a flame?
火柴头有容易烧着的东西，一摩擦生热就点着了。
A match head has stuff that catches fire easily, and rubbing makes heat that lights it.
难度 入门 · 适合 幼儿(3-6)
CC BY 4.0 · 已核验 · Verified 2026-08-23
来源 · Source
Brown, LeMay 等,《Chemistry: The Central Science》第14版,Pearson,2017
T. L. Brown et al., Chemistry: The Central Science, 14th ed., Pearson, 2017
#火柴 #燃烧 #火
为什么蜡烛点着后上面的蜡会化掉？
Why does the wax on a lit candle melt?
火苗的热把旁边的蜡烤化，变成蜡油，火灭了又会变硬。熔化的蜡会被灯芯吸上去，遇到火就烧出光和热。
The flame's heat melts the nearby wax into oil, which hardens again when the flame goes out. The melted wax is drawn up the wick and burned, giving light and heat.
难度 入门 · 适合 小学低段(6-8)
CC BY 4.0 · 已核验 · Verified 2026-08-23
来源 · Source
Brown, LeMay 等,《Chemistry: The Central Science》第14版,Pearson,2017
T. L. Brown et al., Chemistry: The Central Science, 14th ed., Pearson, 2017
#蜡烛 #熔化 #火