Analysis of the pH of sodium cyanide
Sodium cyanide is unique in the field of chemical industry, and it is related to various reactions and applications, and the identification of its pH is particularly critical.
Sodium cyanide ($NaCN $) is a strong base and weak acid salt. In the water environment, cyanogen ions ($CN ^ - $) will combine with hydrogen ions ($H ^ + $) generated by water ionization, causing the ionization equilibrium of water to shift to the right, and the concentration of hydroxide ions ($OH ^ - $) will increase. This hydrolysis process can be described in the ion equation table: $CN ^ - + H_2O\ rightleftharpoons HCN + OH ^ - $.
After theoretical calculation and experimental determination, the sodium cyanide solution is alkaline. Its specific pH value is not a fixed number, depending on the concentration of the sodium cyanide solution. Generally speaking, at room temperature (25 dollars ^ {\ circ} C $), if the concentration of sodium cyanide solution is $c $ ($mol/L $), according to the expression of hydrolysis equilibrium constant $K_h =\ frac {[HCN] [OH ^ -]} {[CN ^ -]} $, and $K_w = [H ^ +] [OH ^ -] $, $K_a $ (the ionization constant of $HCN $), you can get $[OH ^-] = \ sqrt {K_h\ times c} $, and then infer $pH = 14 +\ lg\ sqrt {K_h\ times c} $.
In practical use, the pH value of sodium cyanide solution is often determined by precise instruments, such as pH meter. This is because the pH value of the solution has a significant impact on the direction, rate, and purity of the product of the chemical reaction. If sodium cyanide is used to extract gold in a metallurgical process, the pH value of the solution needs to be strictly controlled to ensure the leaching rate of gold and the subsequent separation and purification effect.
In summary, we are well aware of the pH characteristics of sodium cyanide solutions and the related laws of pH value, which are of great significance in many fields such as chemical practice and scientific research exploration. In order to properly use sodium cyanide and avoid latent risks, we have laid a solid theoretical and practical foundation.
