High-purity drugs usually exhibit the following physical properties: 1. **Crystal form**: High-purity drugs usually show a clear crystal structure, such as crystalline salt or powder, and have a uniform form. 2. **Color**: The color of the drug is often relatively single, and there is no color of impurities. Many high-purity drugs are colorless, white or slightly yellow. 3. **Solubility**: High-purity drugs usually have high solubility in water or other solvents, showing good solubility characteristics. 4. **Odor**: Some drugs may have a distinct odor. High-purity drugs have a clear odor, but some drugs may be odorless or have a slight odor. 5. **Melting point and boiling point**: High-purity drugs often have clear melting points and boiling points. These values are specific in the chemical specifications and may change when the purity is lower. 6. **Density**: The density of high-purity drugs is usually stable, and mixing with other substances that are not related to purity may cause density changes. 7. **Chemical reactivity**: High-purity drugs can undergo predictable chemical reactions with specific reagents and show stability. These physical properties are important when analyzing and identifying drugs, helping law enforcement and scientists to recognize and classify different types of drugs.