Final answer:
Option 1: In a reaction between HCl and H₂O, HCl acts as a Lewis acid by donating a proton, and H₂O acts as a Lewis base by accepting a proton. Therefore, the correct identification is Acid: HCl, Base: H₂O.
Step-by-step explanation:
To identify a Lewis acid and a Lewis base in a reaction, we must look for the substance that is electron deficient and the substance that donates an electron pair, respectively. In the context of HCl reacting with other substances, a Lewis acid is a species that can accept a pair of electrons, while a Lewis base is a species that can donate a pair of electrons.
When HCl (hydrogen chloride) reacts with H₂O (water), the HCl acts as a Lewis acid by donating a proton (H+) and H₂O acts as a Lewis base by accepting the proton, forming hydronium ions (H₃O+). Similarly, when HCl reacts with NaOH (sodium hydroxide), HCl donates a proton and is the Lewis acid, whereas NaOH, having a hydroxide ion (OH⁻) that can accept a proton, serves as the Lewis base.
Thus, the correct identification would be:
- Acid: HCl, Base: H₂O
None of the other combinations provided (2, 3, and 4) correctly identify a Lewis acid-base pair based on their properties in the reactions described.