LABORATORY MANUAL 25 



(1) Put a little limewater into a clean empty bottle and 

 shake it. 



(2) Place a piece of charcoal on a combustion spoon and 

 hold in a gas flame until it glows (i.e. burns without flame). 

 Lower it then into a bottle of air and keep it there as long as 

 it glows. After removing the spoon and coal, pour into the 

 bottle a little limewater; cover the mouth of the bottle and 

 shake it. Describe any change in the limewater. 



(3) By means of a glass tube, breathe through some fresh 

 limewater in a beaker. Describe the effect. 



RESULTS 



1. What compound is made when carbon is burned in air 

 or in oxygen? 



2. Give two other names for " burning." 



3. What physical effect did the burning of the charcoal 

 have on the air in the bottle? 



4. How did the gas made by burning carbon affect the 

 appearance of the limewater? 



5. In what other case was a similar effect produced? 



6. What proof did your experiment give that exhaled 

 air differs from air inhaled? 



7. What chemical process must occur in the body to cause 

 this difference? 



8. Why is the living body warmer than the outside air? 



EXERCISE XVIII (Textbook 181) 

 TESTS FOR ACID, BASIC, AND NEUTRAL SOLUTIONS 



MATERIALS: Solution of an acid (sulphuric), a base 

 (ammonium hydroxide), and a neutral substance (common 

 salt), a glass rod, narrow strips of pink, blue, and lilac litmus 

 papers. 



