The heat of combustion of ethanol into carbon dioxide and water is –327 kcal at constant pressure. The heat evolved (in cal) at constant volume and `27^(@)C` (if all gases behave ideally) is (R = 2 cal `mol^(–1) K^(–1)` __________.

Explanation

To solve the problem, we need to find the heat evolved at constant volume (ΔU) from the given heat of combustion at constant pressure (ΔH). We will use the relationship between ΔH and ΔU, which is given by the equation:

\[ \Delta H = \Delta U + \Delta nRT \]

### Step 1: Identify the given values
- ΔH (heat of combustion) = -327 kcal
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