How does the purity of ethanol affect its use as a fuel?

The purity of ethanol significantly influences its efficiency and performance as a fuel.

The purity of ethanol is a crucial factor when considering its use as a fuel. Pure ethanol, also known as anhydrous ethanol, has a higher energy content than impure or hydrated ethanol. This means that the purer the ethanol, the more energy it can produce when combusted, making it a more efficient fuel.

Impurities in ethanol, such as water, can lower its energy content and thus its efficiency as a fuel. Water in ethanol can also cause phase separation, where the ethanol and water separate into two layers, with the water layer sinking to the bottom. This can lead to engine problems if used in vehicles, as the water can cause corrosion and damage to the engine parts.

Moreover, the purity of ethanol can affect its volatility, which is the ability of a liquid to change into a gas. Pure ethanol is more volatile than impure ethanol, meaning it evaporates more readily. This is important in fuel applications, as the fuel needs to vaporise in order to mix with air and burn efficiently in the engine.

In addition, the purity of ethanol can influence its miscibility, or ability to mix with other substances. Pure ethanol is completely miscible with petrol, making it a suitable additive to increase the octane rating of petrol and reduce harmful emissions. However, impure ethanol may not mix as well, potentially leading to uneven combustion and reduced engine performance.

Therefore, the purity of ethanol plays a significant role in determining its suitability and effectiveness as a fuel. It affects its energy content, volatility, miscibility, and potential for causing engine damage, all of which are important considerations in fuel applications.