碳(tan)酸氫(qing)鈉（NaHCO?）（Sodium Bicarbonate），俗稱小蘇打。白(bai)色細小晶(jing)體(ti)，在水(shui)中(zhong)的溶解度小于(yu)碳酸(suan)鈉(na)(na)。它也是(shi)一種(zhong)工業用(yong)(yong)化(hua)學品，低(di)毒。固體(ti)50℃以上開始逐漸分(fen)(fen)解生成碳酸(suan)鈉(na)(na)、二氧化(hua)碳和(he)水(shui)，440℃時完全分(fen)(fen)解。碳酸(suan)氫鈉(na)(na)是(shi)強堿(jian)與弱酸(suan)中(zhong)和(he)后(hou)生成的酸(suan)式(shi)鹽，溶于(yu)水(shui)時呈現弱堿(jian)性(xing)。此特性(xing)可使(shi)其作(zuo)為食品制作(zuo)過(guo)程(cheng)中(zhong)的膨松劑。碳酸(suan)氫鈉(na)(na)在作(zuo)用(yong)(yong)后(hou)會殘留碳酸(suan)鈉(na)(na)，使(shi)用(yong)(yong)過(guo)多會使(shi)成品有堿(jian)味(wei)。

碳酸氫鈉為白色(se)晶(jing)體，或不透明單斜晶(jing)系細微(wei)結晶(jing)。比重(zhong)2.15。無(wu)臭、味咸，可溶(rong)于(yu)水，微(wei)溶(rong)于(yu)乙醇。25℃時溶(rong)于(yu)10份(fen)水，約18℃時溶(rong)于(yu)12份(fen)水。其水溶(rong)液因水解而呈微(wei)堿(jian)性，常(chang)溫中性質穩定，受熱易分(fen)解，在(zai)50℃以上(shang)逐漸(jian)分(fen)解，在(zai)440℃時完全失去二氧化碳，在(zai)干燥空(kong)(kong)氣(qi)中無(wu)變化，在(zai)潮濕空(kong)(kong)氣(qi)中緩慢分(fen)解。

碳酸(suan)氫鈉(na)可(ke)(ke)直接作(zuo)(zuo)為(wei)(wei)制藥(yao)工(gong)(gong)(gong)(gong)業(ye)(ye)(ye)(ye)的(de)原(yuan)料，用(yong)(yong)(yong)于(yu)治療胃酸(suan)過多。還可(ke)(ke)用(yong)(yong)(yong)于(yu)電影制片、鞣(rou)革(ge)、選礦、冶煉、金屬熱處(chu)(chu)理，以及用(yong)(yong)(yong)于(yu)纖維、橡膠(jiao)工(gong)(gong)(gong)(gong)業(ye)(ye)(ye)(ye)等。同時用(yong)(yong)(yong)作(zuo)(zuo)羊毛的(de)洗滌(di)劑(ji)(ji)(ji)，以及用(yong)(yong)(yong)于(yu)農業(ye)(ye)(ye)(ye)浸種等。食品工(gong)(gong)(gong)(gong)業(ye)(ye)(ye)(ye)中(zhong)一(yi)種應用(yong)(yong)(yong)廣泛的(de)疏松劑(ji)(ji)(ji)，用(yong)(yong)(yong)于(yu)生產餅(bing)干、糕點、饅(man)頭、面包等，是(shi)汽水飲料中(zhong)二氧化碳的(de)發(fa)(fa)(fa)生劑(ji)(ji)(ji)；可(ke)(ke)與(yu)(yu)明(ming)礬復合(he)為(wei)(wei)堿性(xing)發(fa)(fa)(fa)酵粉，也(ye)可(ke)(ke)與(yu)(yu)純堿復合(he)為(wei)(wei)民用(yong)(yong)(yong)石(shi)堿；還可(ke)(ke)用(yong)(yong)(yong)作(zuo)(zuo)黃油(you)保存劑(ji)(ji)(ji)。消(xiao)防器材中(zhong)用(yong)(yong)(yong)于(yu)生產酸(suan)堿滅火機(ji)(ji)和泡沫滅火機(ji)(ji)。橡膠(jiao)工(gong)(gong)(gong)(gong)業(ye)(ye)(ye)(ye)利用(yong)(yong)(yong)其與(yu)(yu)明(ming)礬、H發(fa)(fa)(fa)孔劑(ji)(ji)(ji)配(pei)合(he)起(qi)均勻發(fa)(fa)(fa)孔的(de)作(zuo)(zuo)用(yong)(yong)(yong)用(yong)(yong)(yong)于(yu)橡膠(jiao)、海棉生產。冶金工(gong)(gong)(gong)(gong)業(ye)(ye)(ye)(ye)用(yong)(yong)(yong)作(zuo)(zuo)澆鑄鋼錠(ding)的(de)助熔(rong)劑(ji)(ji)(ji)。機(ji)(ji)械工(gong)(gong)(gong)(gong)業(ye)(ye)(ye)(ye)用(yong)(yong)(yong)作(zuo)(zuo)鑄鋼(翻砂(sha))砂(sha)型(xing)的(de)成型(xing)助劑(ji)(ji)(ji)。印(yin)染(ran)(ran)工(gong)(gong)(gong)(gong)業(ye)(ye)(ye)(ye)用(yong)(yong)(yong)作(zuo)(zuo)染(ran)(ran)色印(yin)花(hua)的(de)固(gu)色劑(ji)(ji)(ji)，酸(suan)堿緩沖(chong)劑(ji)(ji)(ji)，織(zhi)物(wu)染(ran)(ran)整的(de)后方處(chu)(chu)理劑(ji)(ji)(ji)。染(ran)(ran)色中(zhong)加入小蘇打可(ke)(ke)以防止紗筒產生色花(hua)。醫藥(yao)工(gong)(gong)(gong)(gong)業(ye)(ye)(ye)(ye)用(yong)(yong)(yong)作(zuo)(zuo)制酸(suan)劑(ji)(ji)(ji)的(de)原(yuan)料。

應放置室內陰涼干燥處，避免日曬雨淋。