The diagram illustrates the structure of a compound named ethanoic anhydride. When $1\ \text{mol}$ of ethanoic anhydride reacts with water, $2\ \text{mol}$ of a carboxylic acid are produced only. This carboxylic acid then reacts with ethanol to make an ester. How many moles of water react with $1\ \text{mol}$ of ethanoic anhydride, and what is the structure of the ester?