Final answer:
The reaction between aluminum sulfide and water proceeds due to the formation of insoluble aluminum hydroxide and the escape of hydrogen sulfide gas, shifting the equilibrium toward product formation.
Step-by-step explanation:
The student is perplexed about the reaction Al2S3(s) + 6H2O(l) → 2Al(OH)3(s) + 3H2S(g), which seemingly goes against the common principle that reactions typically proceed from strong acids to weak acids.
In this particular case, water (H2O) which is less acidic is reacting to form hydrogen sulfide (H2S), which is a stronger acid. However, the driving force behind this reaction is the solubility and stability of the products rather than the acid strength.
Aluminum hydroxide (Al(OH)3) is an insoluble precipitate that forms readily in water, whereas H2S is a gas that escapes from the reaction mixture.
This removal of products from the reaction environment shifts the equilibrium toward the products' side, allowing the reaction to proceed despite the usual acid base expectations.