Syringe is a common medical appliance. As early as the 15th century, the principle of syringe was put forward. It is mainly used for injection or extraction. The syringe is composed of a needle with a small hole at the front end and a matching piston rod. The syringe is used to inject a small amount of liquid or it into or extract from areas inaccessible by other methods. When the core rod is pulled out, the liquid or gas is sucked in from the small hole at the front of the syringe, and the liquid or gas is squeezed out when the core rod is pushed in. The process of extracting or injecting gas or liquid with a syringe and needle is called injection.
1、 Can take a certain amount of liquid and gas
2、 Use the movement of the syringe piston to change the volume to determine the volume of liquid or gas.
3、 Use the movement of the syringe piston to change the size of the capacity to change the pressure of other devices.
The medical syringe has the following advantages: good sealing; Transparent and graduated for easy observation; The characteristics and advantages that are cheap and easy to obtain can be systematically summarized and studied according to the characteristics and advantages of the injector, and consciously use these characteristics and advantages, and make careful design, so that many experiments can be done to achieve multiple uses of one thing, and give full play to the role of the injector in chemical experiments.
1. Verify that there is a gap between molecules
Draw equal volume of air and red ink from two syringes of the same size.
Then block the front outlet of the syringe with your finger and push the piston forward to compress the material in the syringe barrel. You will find that the piston of the syringe with air is easy to push forward, while the piston of the syringe with red ink is difficult to push forward. It not only shows that there is a gap between molecules, but also shows that the gap between gas molecules is larger than that between liquid molecules, so it is easy to compress. The common phenomenon in life is that oxygen and petroleum gas are compressed and stored in steel cylinders.