Wednesday 22 April 2015

Disappearing As If by Magic

Why does salt disappear when you put it in a glass of water and stir it? Similarly, where does the sugar go to when you do the same? You can easily wipe off the writings and drawings that you made with a whiteboard marker using a cloth or duster, but when you accidentally use a permanent marker, oops! No matter how hard you scrub, it just would not rub off. Why is this so? 

Solvents are chemicals that will cause something to dissolve, disperse or separate into tinier particles. They will break the chemical bonds of the substance, for example salt, without altering its chemical properties. 

Water is considered a universal solvent because it is able to dissolve most compounds. When salt or sugar is stirred into a glass of water, the molecules that make up the salt or sugar is broken down into smaller units that are not visible with the unaided eye. 
Acetone is a solvent that is used to remove nail polish, whereas ethanol, which is a type of alcohol, is a solvent that is used to remove paint.

So, if you use a permanent marker on a whiteboard by mistake, run to the nearest pharmacy and get some alcohol swabs. These small square pieces of cotton soaked in ethanol will do the trick of wiping off the ink.

Experiment: Making an eggshell go soft

1 egg, drinking glass, vinegar

1. Gently place the egg into the glass. 
2. Pour vinegar over the egg to completely cover it.
3. Wait 2 to 3 days. Take the egg out of the glass, and feel the shell.
The vinegar reacts with the calcium in the eggshell, dissolving it. This makes the shell feel soft and rubbery. This shows the importance of calcium to make the shell strong, just like the calcium in our bones.

Dissolve [dih-zolv] to break up or undo a tie or bond
Molecule [mol-uh-kyool] a quantity of a substance, whose weight is numerically equal to its molecular weight 
Compound [kom-pound] composed of two or more parts, elements, or ingredients
Acetone [as-i-tohn] a colourless, volatile, flammable liquid 

Shared by Surain A. Victor
Guest blogger

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