SHOWING THATCARBONDIOXIDE IS APRODUCT OF EXHALATION
Materials: Buy a bottle oflime water at a drugstoreor soda fountain.
You will also need adrinkingstraw and a tumbler.
Follow this procedure: Take in a deep breath throughyour nose and
mouth. Let the air out by blowingthroughthe straw into the glass of lime
water.
You will observe:As the exhaled air bubblesthroughthe straw, the clear
lime water becomes milky.
Carbondioxide, the waste gas given off inexhalation,causes a chemical
change in lime water which results in a clouded appearance. Since this is
what happened when you breathed throughthe straw into the lime water,
you have provedthatcarbondioxide is an element of exhaled air.SHOWING THAT WATER VAPOR IS PRESENT IN EXHALED AIR
Materials:Amirror.
Follow this procedure: Take a deepbreathwhilestandingbefore amirror
orholdinga handmirrorin front of your mouth. Now, exhaleagainstthe
surface of themirror.