Tuesday, February 3, 2015

Fun Chemistry with Kids. 1. Density

The magic experiment

Every child has experimented stacking boxes or cubes but how people know how to stack liquids.  Kids will be amazed by this experiment especially if food coloring is used to create nice bright colored liquids.  With the help of a little chemistry your child will be able to stack liquids.  This is based on density.  Density is a very important concept as it is one reason why things float.  In this experiment the liquid that floats on top is the least dense liquid and the one that sinks is the most dense liquid.

Density the Science

Density measures the amount of mass in a given volume.  The formula used is density=mass/volume.
Mass refers to the weight of the sample or object-in other words how heavy the object it.
Volume refers to the space the object occupies.
Density refers to how tightly the thing is stuffed into the space.

Think of a square brick versus a square bath sponge of the same size.  Which one is heavier?  Which one sinks and which one floats?  In other words if the weight of an object increases but volume remains the same, the density has to increase.

The experiment
Apparatus and Materials

measuring cups
a glass or a jar to layer the liquids in
food baster
Different liquids-honey, light corn syrup, dish soap, water, oil.  (other liquid suggestions-milk, fruit juice, baby oil and many more)
Food coloring

1.  Measure each liquid into a measuring cup.  Choose an appropriate amount to fit into the container that you want to fill.  I used the 1/4 cup measure.  Be consistent with the amount of each liquid.  Color the liquid using food coloring if desired.

2.  Starting at the bottom pour the honey into the center of the glass.  Try not to touch the sides while pouring.

3.  Allow the honey to settle.  Carefully pour in the corn syrup.  (I colored mine pink).  Again try to pour slowly into the middle of the glass.  Try not to allow the syrup to touch the outside while pouring.  This may result in a sticky mess on the glass.

4.  Once the corn syrup has settled.  Carefully add the dish soap to the center of the glass.  Again try not to let the dish soap touch the sides.

5.  To stack the less dense liquids such as water, it is best to use a food baster to let them trickle down the edge of the glass.  You will see some mixing but the layers will separate out.  To use the food baster, squeeze the top and dip the end into the liquid.  Draw up the liquid by releasing the squeeze.  Aim the food baster to the edge of the glass and slowly squeeze the top again to release the liquid.  In the photograph I am adding blue water.

6.  Repeat as in number 5 for the oil.  In this photograph all 5 layers can be seen.

7.  Continue experimenting by finding objects in your house.  See if they float or if they sink.  Maybe some objects will not sink all the way to the bottom.  Some will.  In the next photograph I have added a cherry tomoto and a penny.  Other objects to try would be nuts, buttons, screws, popcorn etc. Perhaps time how long the object takes to get to the layer.

More fun with density

To experiment further with density try the following simulation