1. **Problem statement:** We have a carbocation with a positive charge on the second carbon in a chain, and an ethyl side chain on the third carbon. We want to show the 1,2-hydride shift that leads to a more stable carbocation. 2. **Concept:** A 1,2-hydride shift involves the migration of a hydride ion (H-) from an adjacent carbon to the carbocation center. This rearrangement moves the positive charge to a new position, often resulting in a more stable carbocation. 3. **Step-by-step:** - Identify the carbocation center: carbon 2 has the positive charge. - Identify the adjacent carbon with a hydride to shift: carbon 3 has a hydrogen that can migrate. - Draw a curved arrow from the C-H bond on carbon 3 to the carbocation center on carbon 2, indicating the hydride shift. - After the hydride shift, the positive charge moves to carbon 3. 4. **Resulting structure:** - Carbon 3 now bears the positive charge. - Carbon 2 is now neutral because it gained the hydride. - The ethyl side chain remains attached to carbon 2. 5. **Formal charges:** - Show the positive charge on carbon 3. - No other formal charges are present. This rearrangement stabilizes the carbocation because the positive charge is now on a more substituted carbon, which is more stable due to hyperconjugation and inductive effects.