VETERINARY STATE BOARD 

 QUESTIONS AND ANSWERS 



CHEMISTRY 



Distingtiish between chemistry and physics. 



Physics is the science of matter and energy. It deals with those 

 changes in matter which do not involve a change in composition. 

 It also deals with the doctrine of equilibrium and vdth that of 

 motions. The latter are visible, as those of mass, in faU, projection, 

 rotation, propagation in a plane, etc.; or invisible, and only per- 

 ceptible by their results, as sound, heat, light and electricity. 



Chemistry reveals to us the composition of matter, and in the 

 formation of new compounds, acquaints us with the rules and laws 

 by which its various forms act upon one another. It deals with 

 those changes in matter which do involve a change in composition. 



Define specific gravity. If the specific gravity of a substance is 1.5, 

 how many c.c. of distilled water will ten grammes represent? 



The specific gravity of a substance is the ratio between the 

 weight of any volume of the substance and the weight of a like 

 volume of some other substance taken as a standard. For solids and 

 liquids, the standard is distilled water at its temperature of maxi- 

 mum density ; for gases and vapors, the standards are hydrogen and 

 air at a temperature of 0° C. and a barometric pressure of 76 centi- 

 metres of mercury. 



If the specific gravity of the substance in question is 1.5, 10 

 grammes would equal 15 grammes of water; 1 gramme of water 

 equals 1 c.c, hence 15 grammes would equal 15 c.c. 



How is the specific gravity of a liquid determined? 



There are several ways. The hydrometer is usually employed, 

 or comparisons can be made of the weights of equal volumes of the 

 liquid and water. 

 What effect on the volume of a gas has (a) change of pressure, (b) 

 change of temperature? 

 (a) The volume of a gas varies inversely as the pressure upon 

 it (Boyle's law). 



(b) All gases approximately expand equally for equal rises of 



I. 



