9. Fill two test tubes half full of distilled water. Breathe for a few moments through 

 a glass tube into the water in one of the tubes. Add limewater to the water in both tubes, 

 (a) Observe any difference, (b) Infer the cause of this difference, (c) What is the source 

 of the gas just tested? We may say that the gas was dissolved in the water. 



10. Test the hydrant water to determine whether or not any carbon dioxide gas is present 

 in solution, (a) Record the result of the test, (b) Infer concerning the presence of carbon 

 dioxide in soil water. 



11. There are three states of matter — solid, liquid, and gas. (a) The solubility of what 

 state of matter is illustrated in 'experiment 7? (b) Experiment 8? (c) Experiments 9 and 10? 



Part D. Soil Water and Rain Water. 



12. (a) Why may ordinary well water be taken as a sample of soil water? Place a drop 

 of well water on a clean glass plate. In another place on the same plate, put a drop of rain 

 water. Lay the plate on the radiator or place where it will dry readily. (Recall the solvent 

 power of water, Part C of this exercise.) (b) Observe if there is any difference between the 

 spots left on the plate as a result of evaporation, (c) Infer in full the cause of any differ- 

 ence observed, (d) Explain how rain water may become soil water with the characteristics 

 of the well water just examined. 



13. Fit a test tube with a one-hole rubber stopper through which passes an elbow tube. 

 Fill the tube one-fourth full of the salt solution. Boil the solution, allowing the steam to 

 pass through the elbow tube into another test tube, (a) Observe and taste what collects 

 within the second tube, (b) How does it differ from the original? This process is called 

 distillation. Notice that the first step in the process is evaporation, the second condensation. 

 (c) Infer why rain water closely resembles distilled water, (d) Infer how soil water might 

 become rain water.* 



•Note: Investigations indicate that about 70% of the precipitation on the land surface is derived from 

 evaporation from the land surface. 



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