Properties of matter 



The regulation of physiological processes involves an impressive 

 number of physical variables. Hence the study of protoplasm depends 

 extensively upon the physical sciences. Certain aspects of these sciences 

 fundamental to an understanding of biochemistry are assembled in 

 this chapter. The concept of the state of matter and various proper- 

 ties of biological importance when matter exists in one or more of 

 these states are included in the discussion. 



GASES 



Physical Behavior 



In gases the individual particles are relatively far apart and move 

 at high velocities in a rather random manner. The molecules exert 

 little attraction for one another and possess energy of motion sufficient 

 to overcome this attraction. Thus the particles distribute themselves 

 throughout any evacuated space into which the gas is placed. As a 

 result the gas assumes the volume and shape of the system. The gas 

 has no volume or shape inherently its own. 



The molecules travel straight paths except for occasional collisions 

 with one another, but even after colliding the motion is linear, the 

 molecules merely being deflected at some angle with respect to the 

 former path. When a molecule collides with a wall bounding the gas, 

 the molecule changes direction. In so doing a force is exerted on the 

 wall, and the effect of repeated collisions with a given wall area is 

 called pressure. Thus a confined gas exerts a pressure on the container 



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