To convert 80 grams of a substance into milliliters, one must first know the density of the substance. Grams are units of mass, while milliliters are units of volume.
For example, 80 grams of pure water at 39.2 degrees Fahrenheit is equal to 80 milliliters. When that same mass of water reaches its boiling point at 212 degrees Fahrenheit, its lower density means that its volume expands to 83.47 milliliters.
Different densities mean different volumes for 80 grams of other substances as well. Eighty grams of butter is 92.49 milliliters, while 80 grams of maple syrup is 58.74 milliliters. Eighty grams of dry sand is 62.45 milliliters, but 80 grams of packed wet sand is much denser and has a volume of just 38.42 milliliters.