Science Projects With Chalk & Vinager

Monday, January 13, 2014

Science Projects With Chalk & Vinager

Vinegar mimics the effect of acid rain in science experiments.

On the pH scale vinegar is described as acidic and chalk is a base. The pH (potential hydrogen) scale describes how acidic or alkaline a substance is, like temperature describes how hot or cold something is. When vinegar and chalk come together a chemical reaction occurs. Experiments with vinegar and chalk can help study conditions in the real world.

Projects With Chalk

Chalk is a soft calcite. Chalk, limestone and marble share the same parentage --- they all are made of calcium carbonate, a porous substance that absorbs water easily. Create a project to demonstrate this property. Take a piece of chalk. Try and obtain chalk made from natural calcium carbonate. Weigh it. A postal scale or spring balance will work. Immerse the chalk in a glass of water. Take it out of the water after three minutes and weigh again. Note the weight. Continue to weigh every three minutes until you notice no further weight increase. Note the time taken to reach the final weight. This experiment shows how easily chalk and limestone rocks absorb water.

Projects With Vinegar

Take ten dull-looking pennies and wash them in water. The pennies still look dull. Now take a non-metallic bowl of water and stir in one quarter cup of vinegar along with a teaspoon of salt. Put the pennies in the bowl. They begin to change color. Take them out of the water after five minutes. Do they look shinier? The salt-and-vinegar mixture is an acid that cuts through the copper oxide on the penny making them gleam again. Leave half the pennies to air dry and wash the other pennies in running water then dry them on a paper towel. What do you see? The washed pennies retain their shine but the unwashed pennies turn blue-green. When the copper-oxide layer is washed away oxygen in the air and chlorine from the salt combine with the copper atoms of the penny to form a blue-green compound called malachite.

Projects With Chalk and Vinegar

Create a project that mimics the effect of acid rain on exposed marble and limestone. Take two glass tumblers. Pour water in one tumbler and vinegar in the other. In each tumbler submerge a piece of chalk. Look for chalk that is made from calcium carbonate, not one made of gypsum or some synthetic material. What happens when you drop the chalk in vinegar? It fizzes, as the oxygen in the vinegar combines with the calcium carbonate. Tiny particles fall to the bottom of the glass. The particles are calcium acetate --- calcium from the chalk combined with hydrogen from the vinegar. Set the glasses in a place where they will not be disturbed. Observe them and make notes of what is happening. The chalk in the water gets wet, but the size does not change. The chalk in vinegar dissolves just as limestone and marble are dissolved by acid rain.

Bone-Eating Vinegar

Drop a chicken bone in a glass tumbler filled with vinegar. Cover and put aside for a week. The calcium in the bone dissolves in the vinegar making the bone bend like rubber. Will vinegar eat away an eggshell? Put a hard-boiled egg in a tumbler of vinegar. The eggshell is calcium carbonate, which dissolves in the vinegar. In a few hours the hard shell becomes soft and rubbery. In a few days the shell is totally dissolved. As an extension of the project leave this egg exposed to the air for a day. The calcium in the egg absorbs carbon from the carbon dioxide in the air and hardens again. Put the egg back into the vinegar for a day? What happens? The egg becomes rubbery. Drop it from about a foot above the floor. The egg will bounce back.

Dryer lint

Monday, January 13, 2014