What is the specific gravity (SG) of pure ethanol?

The specific gravity of pure ethanol is approximately 0.789 at 20°C, which is commonly rounded to 0.8 for practical purposes. Specific gravity is a comparison of the density of a substance to the density of water, where water has a specific gravity of 1. This means that since ethanol has a lower density than water, it floats when mixed with it.

Understanding specific gravity is essential in brewing and distillation, as it can influence the fermentation process and the quality of the final product. The incorrect options reflect different densities related to liquids but do not accurately represent the specific gravity of ethanol. For example, values like 1.0 would indicate a density equal to that of water (which does not apply to ethanol), and higher figures such as 1.2 suggest a denser liquid than water, which is also not representative of ethanol.