Experiment 16:
Acidic solutions destroy metal and stones
Did you ever hear about acid rain?
Due to the exhaust gases the rain water may corrode stone and metals of buildings and kill trees. People distribute lime powder inside the woods as "medicine".
Corrosive means destroying substances. PROTECT your EYES, use GOGGLES!
*  Left: Pour water from the left vial citric acid and a piece of eggshell.
* Middle: Gas bubbles and foam evolve from the eggshell.
   Stirr, add more water and as much citric acid as the liquid dissolves.
* Right: After one day the eggshell nearly*) disappeared and the liquid is transparent.
   The eggshell is made of limestone which reacted with the citric acid leaving a gas and a
    substance which dissolved in the liquid.
   *) Stronger acids completely remove eggshells and corrode marble and aluminium
 Remember:
Corrosive are liquids which destroy limestone, metals, clothes, skin and even your eyes. So you must always wear goggles during experimentation.

---

Sour cherries = Acid and indicator                                                 Experiment 17         back