Ink 



solution 



Inverted jar 

 for light gas 



Porous cup in 

 position (a) 



Porous cup in 

 position (b) 



Erect jar for 



I heavy gas 



ways IS oxidation of food substances like the oxidation of ordinary fuel? In what 

 ways is oxidation of food substances different from oxidation of orduiary fuel? 



3 To show that slow oxidation liberates heat, place a tablespoon of dry potas- 

 sium permanganate on a folded paper towel in a shallow pan above sand or 

 asbestos. To a crater in the top of the permanganate add a teaspoon of glycerm. 

 Cover with another folded paper towel (to prevent too rapid loss of heat). Rest pan 

 on asbestos pad. Leave undisturbed until there is no doubt as to whether (a) heat 

 is given oflf, or (b) oxidation is taking place. Record results and conclusion. 



4 To find whether germinating seeds give out carbon dioxide, place about 

 two tablespoons of soaked seeds in a sealed flask. Let stand overnight in a warm 

 place. On the following day replace the solid stopper with a two-hole stopper 

 carrying a thistle tube and a bent glass tube leading to a test tube containing Hme- 

 water. Pass the gas from the flask through limewater by pouring water into the 

 thistle tube. Bubble the air from a similar flask containing dry seeds through 

 another test tube of Hmewater. Compare results and note conclusions. 



5 * To find out whether the air we exhale contains more carbon dioxide than 

 the air we inhale (that in the room), inhale and exhale through two separate 

 bottles of limewater several times. Compare results and note conclusions. 



6 To demonstrate the diffusion of gases, set up an apparatus as in the dia- 

 gram. Fill an inverted quart jar with a light gas, such as hydrogen or illuminat- 

 ing gas, and place it over the porous cup in the position (a). Similarly, fill an up- 

 right jar with carbon dioxide and place it around the porous cup as shown in 

 position (b). Compare what happens in the ink-solution indicator as you test 

 different gases, and account for the results. 



94 



