A 250 ml Erlenmeyer conical flask with a narrow mouth is a laboratory container used for mixing, heating, and measuring liquids.

– Shape: Conical, with a narrow mouth and a rounded bottom
– Material: Borosilicate glass or soda-lime glass
– Mouth: Narrow, for reduced spillage and easy handling
– Capacity: 250 ml
– Gradations: May have graduated markings for measuring volumes

Uses:
1. Titration: For accurate titration reactions, where the narrow mouth facilitates precise liquid transfer.
2. Chemical reactions: For conducting chemical reactions, heating, and mixing substances.
3. Solution preparation: For preparing solutions, dilutions, and mixtures.
4. Heating and boiling: For heating substances, boiling, or sterilizing equipment.
5. Laboratory measurements: For accurate measurements of liquids.
6. Education and training: For teaching laboratory techniques, chemistry, and biology.
7. Research and development: For experimentation and analysis in various industries, such as pharmaceuticals, biotechnology, and environmental science.

The 250 ml size is a popular choice for many laboratory applications, offering a good balance between capacity and ease of handling.