How is compressed gas released

By definition, the particles of gases are far apart and gases tend to fill their container, even if the container is a laboratory room. Tanks of compressed gas come from the supplier capped to prevent the gas from escaping. In the lab a chemist or technician attaches a regulator to the tank and secures the tank to a stable fixture. 

Explain why the flow of compressed gas must be controlled for practical use. 

Predict what would happen if the valve on a full tank of compressed gas were suddenly opened all the way or if the full tank were punctured. 

The fact that substances can change form, as in the example of water changing to steam, is another important concept in chemistry. If you review what you just learned about physical properties of substances, you can see that because the particular form of a substance is a physical property, changing the form introduces or adds another physical property to its list of characteristics. In fact, resources that provide tables of physical and chemical properties of substances, such as the CRC Handbook of Chemistry and Physics, generally include the physical properties of substances in all of the states in which they can exist. 

Describe the characteristics that identily a sample of matter as being a substance. 

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