Brainspace – July 2019

brainspace SUMMER 2019 31

ACID RAIN

1. Break chalk into small pieces. You Will Need:


2. Fill half the glass container with vinegar.


3. Add one piece of chalk to the container and observe the changes that
   take place.


4. Record what you see happening.


5. Add another piece of chalk to the container. Record what you
   see happening.


6. Continue to add chalk until you do not see any more changes
   taking place.
   
   
   • Chalk
   
   
   • Vinegar
   
   
   • Clear container
   
   
   • Measuring cup
   
   
   
   

Safety First!

Be careful not to rub your eyes

when handling vinegar. Wash

your hands immediately after

finishing this experiment.

When the chalk is added to an acid like vinegar, a chemical
reaction occurs. It’s called a neutralization. This occurs
when an acid and a base are combined. During the reaction
a gas and a neutral solution are formed. The gas produced
in this activity is carbon dioxide and can be seen as bubbles
in the vinegar. Crushing the chalk before adding it to the
vinegar speeds up the reaction. Keep adding more chalk
and eventually the bubbles stop forming. This shows that

all the acid in the vinegar has been used up. This reaction

occurs in the environment when weak acids in rain react

with limestone and other rocks. The result is erosion (the

wearing away of rock). It occurs very gradually. Limestone

and marble are made of the same material as chalk, and are

used for constructing buildings and statues. Rain that is

too acidic will “eat away” at these structures very quickly,

the same way the vinegar ate away at the chalk.

What's happening?

Use Zappar. Scan for a video demonstration.