Goods Shall be fit for Such Purpose
I like your post. One interesting point is that Blum states that on instantaneous transactions or exchanges, where no one makes a promise or commitment, or no warranty relating to the goods, there is no role for contract law to occupy in enforcing the exchange.  Yet, if we look at UCC §2-315 which deals with implied warranties and fitness for a particular purpose, the section states: “Where the seller at the time of contracting has reason to know any particular purpose for which the goods are required and that the buyer is relying on the seller’s skill or judgment to select or furnish suitable goods, there is unless excluded or modified under the next section an implied warranty that the goods shall be fit for such purpose.”  While this provision of the UCC is normally reserved for merchants, the provision is applicable to non-merchants as the situation justifies. 
So, if on a hot sunny day, after the seller watches the buyer finish off the last of his laps around the jogging track, the buyer approaches the seller to perform an instantaneous exchange where the buyer is purchasing a bottle of water from the seller. The seller knows the water is meant to be ingested by the buyer. The seller sells the buyer his last bottle of water which happens to be the non-potable water he usually sells to people whose car radiators have over heated. The two parties complete the exchange. The buyer drinks the water and subsequently the water makes the buyer sick.
The seller argues that the instantaneous transaction was void of promises or commitments and because of that, no contract existed. Therefore, he could not face a cause of action under contract law. On the other hand, the buyer, citing that because of the circumstances the seller knew, or should have known that he wanted to drink the water and because of this fact, the seller had an obligation to sell the buyer potable water. The buyer continues on to claim that given the circumstances, by selling the water, an implied warranty pertaining to the fitness of the water existed and claims there was indeed a contract. The buyer then initiates a cause of action against the seller for a breach of implied warranty of fitness for a particular purpose.
It seems that the particular circumstances surrounding an instantaneous exchange could be argued to satisfy the elements required to form a contract.
 Brian A. Blum, Examples & Explanations: Contracts 4 (6 ed. 2013).
 Steven J. Burton, Contract Law 48 (2014).
 Id. At 49
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