Sodium hydrogen sulfide anhydrous

After the sodium sulfide becomes saturated, it continues to absorb hydrogen sulfide to form Sodium hydrogen sulfide anhydrous:
Na₂S + H₂S → 2NaHS

The absorption of hydrogen sulfide by caustic soda occurs in the gas-liquid phase. One molecule of H₂S reacts rapidly with one molecule of caustic soda. As sodium sulfide approaches saturation, the formation of crystals causes the mixture to become viscous, significantly reducing its fluidity. The reaction heat raises the temperature of the solution, substantially slowing down the reaction rate. The absorption of hydrogen sulfide by sodium sulfide also becomes slower than in the initial stage. As sodium hydrosulfide nears saturation, the reaction rate further decreases, often resulting in incomplete absorption of H₂S gas.Sodium hydrogen sulfide anhydrous.