Why is grass ground with ethanol?

• A. Chlorophyll is more soluble in ethanol
• B. Ethyl alcohol preserves the grass better
• C. Water would extract more pigment than ethanol
• D. Ethanol is cheaper than water

Answer: (A)

Chlorophyll dissolves better in ethanol than in water because of how solubility depends on polarity. Chlorophyll has a largely nonpolar, hydrophobic body with only a small polar region, so it doesn’t mix well with very polar water. Ethanol is moderately polar, so it can surround and dissolve the chlorophyll molecules more effectively. When grass is ground in ethanol, the cell walls break and the pigments are released into the solvent, giving a green solution that can be observed or analyzed. Water would not pull out as much pigment, since chlorophyll isn’t highly soluble in it. The idea isn’t about preserving pigments primarily; it’s about using a solvent that can dissolve the pigment efficiently, which is why ethanol is used.