硫代硫酸钠是硫代硫酸（H2S2O3）的钠盐，硫代硫酸的结构简式可写作HO—SSO—OH，可看作硫酸（HO—SO2—OH）中的一个氧原子被硫原子取代后得到的化合物，自由的硫代硫酸是不稳定的，易分解为S、SO2和H2O，但硫代硫酸的盐可以是稳定的。
Sodium thiosulfate is the sodium salt of thiosulfuric acid (h2s2o3). The structural formula of thiosulfuric acid can be written as ho-sso-oh, which can be regarded as a compound obtained after an oxygen atom in sulfuric acid (ho-so2-oh) is replaced by a sulfur atom. Free thiosulfuric acid is unstable and easy to decompose into s, SO2 and H2O, but the salt of thiosulfuric acid can be stable.
含有5个结晶水的硫代硫酸钠，即Na2S2O3·5H2O，也就是俗称的“大苏打”或者“海波”，是一种常见的工业品或者化学试剂。硫代硫酸根离子有较强的配位能力，能与一价银离子Ag+生成稳定的络离子[Ag(S2O3)2]3-，其稳定常数Kf比常见的银氨络离子[Ag(NH3)2]+高好几个数量级，因此过去常作为照相底片或者相纸的定影剂，以溶解底片或者相纸上未感光的卤化银（以溴化银为主）：→
Sodium thiosulfate containing five crystal waters, namely Na2S2O3 · 5H2O, commonly known as "baking soda" or "Haibo", is a common industrial product or chemical reagent. Thiosulfate ion has strong coordination ability and can form a stable complex ion [Ag (s2o3) 2] 3 - with monovalent silver ion Ag +, and its stability constant KF is several orders of magnitude higher than the common silver ammonia complex ion [Ag (NH3) 2] +. Therefore, it used to be used as a fixing agent for photographic negatives or paper to dissolve the non photosensitive silver halide on negatives or paper (mainly silver bromide): →
硫代硫酸钠有较强的还原性，可以与卤素单质反应，其中与碘的反应是定量的：
Sodium thiosulfate has strong reducibility and can react with halogen, in which the reaction with iodine is quantitative:
是连四硫酸钠，即连四硫酸（H2S4O6）的钠盐，连四硫酸的结构简式是HO—SO2—S—S—SO2—OH，分子中存在S—S—S—S硫链。该反应在分析化学中用于测定碘的含量，滴定时可用淀粉作为指示剂。用5％的硫代硫酸钠溶液浸渍口罩，可防护低浓度的氯气，对皮肤的刺激性要比NaOH等强碱小得多。
Sodium tetrasulfate, Tetrasulfuric acid The structural formula of (h2s4o6) sodium salt and tetrasulfuric acid is ho-so2-s-s-so2-oh, and there is s-s-s sulfur chain in the molecule. This reaction is used to determine the content of iodine in analytical chemistry, and starch can be used as an indicator in titration. Dipping the mask with 5% sodium thiosulfate solution can protect the low concentration of chlorine, and the irritation to the skin is much less than that of strong bases such as NaOH.
硫代硫酸钠还可以作为氰化物中毒的剂，在体内可以将剧毒的氰离子CN-转化为毒性很低的硫氰酸根离子SCN-，以解除CN-的毒性。
Sodium thiosulfate can also be used as an antidote to cyanide poisoning. In vivo, it can convert highly toxic cyanide ion CN - into very low toxic thiocyanate ion SCN - to relieve the toxicity of CN -.
·5H2O加热到约48℃时，Na2S2O3溶解在自身的结晶水中，成为溶液，继续加热则逐渐失去结晶水得到无水物，如果再继续高温加热，Na2S2O3开始分解，分解产物中有少量单质硫成为硫蒸气放出，遇空气可能燃烧发出蓝色火焰，分解产物中还含有SO2等气体，有强烈的刺激性气味，因此工业品硫代硫酸钠也要注意防火。
·When 5H2O is heated to about 48 ℃, Na2S2O3 will dissolve in its own crystal water and become a solution. If it continues to heat, it will gradually lose the crystal water to obtain anhydrous matter. If it continues to heat at high temperature, Na2S2O3 will begin to decompose, and a small amount of elemental sulfur in the decomposition product will be released as sulfur vapor. In case of air, it may burn and emit blue flame, and the decomposition product also contains SO2 and other gases, There is a strong pungent smell, so the industrial sodium thiosulfate should also pay attention to fire prevention.
The above is the main content shared by sodium persulfate. Please continue to pay attention to us for more wonderful content: http://www.jnjhhg.cn
