✔ 最佳答案
燃燒是要三個條件的: 熱力、燃料和氧。
本生燈下面有煤氣供應(有燃料),不打開氣孔時氧和煤氣混合比例不好,不完全燃燒所以熱力不足。打開氣孔至一半火力最高,因為氧和煤氣混合比例洽當,但底部不燒起來因煤氣噴出的力量大把火推在本生燈頂部燃燒。
有時當氣孔完全張開時﹐本生燈可能會在氣孔處燃燒。
本生燈在氣孔處燃燒時叫suck back, 要關氣孔或煤氣開關。
2007-01-13 01:41:58 補充:
有!!!1. Bunsen burner 開or 關氣孔有咩用?唔關air hole, 會有縮火ge 情況出現, 即係d 火而air hole 走出黎, 因為air hole 個hole 同bunsen burner 上面個hole 差唔多大小, 噴出黎d 煤氣就有可能由air hole 出,同埋由上面出...咁你一點火就會好有機會
2007-01-13 01:42:13 補充:
本5air hole ge 位置變左出火位, 出火位就變左抽氣口, 咁樣燒親自己燒親人, 仲有可能點著bench 上易燃ge chemical tim...此時僅計將煤氣制閞掉, 並過一會兒先再掂個bunsun burner...(因為支管好熱...)
2007-01-13 01:42:33 補充:
如果平時close 左air hole sin, d 煤氣就only 得一個出口出, 你點著左之後出火位d火會抽d 煤氣出去, 所以d 煤氣只會向上走, 而唔會由air hole 出, 此時sin 開air hole 就可以幫助增加氧氣和煤氣ge 混合, 令燃點起來的火更高溫...
2007-01-13 01:43:33 補充:
2.同埋flame test 點解要用hydochloric acid?with nichrome wire?參考:It is because con.HCl is a strong acid with only acidic characteristic, most of the cholride salt is soluble in water except lead chloride..... silver chloride also can dissolve in high concentration of chloride solution,
2007-01-13 01:43:49 補充:
so it is easy to remove almost all metallic oxide residue after flame test..... .if you use nitric acid used, the nichrome wire will be destroyed, since the nitric acid is a oxidizing agent