Hands-on Chemistry

We received a chemistry kit and the children were eager to examine it.

Here are the steps we took:
1. What is matter?
I used Unix blocks to demonstrate that matter is made of parts and that these part occupy space.

2. What are the most common states of matter?
I used Unix blocks to show that the structure is rigid when the blocks are connected. This is similar to how the parts of 'solid' matter relate to one another.

I used separated Unix blocks to make analogy to 'liquid' state of matter. I demonstrated how in this 'state' the blocks can 'flow' and occupy some of the space it has been provided and assume the shape of the space it has been provided.

I then separated the Unix blocks further apart to demonstrate the 'gas' state of matter.

3. What are the states of matter for the citric crystals, the baking soda powder, and the water?

This is tricky. The baking soda powder can be made to flow and assume the shape of the container it occupies. The smallest grains of baking powder on the other hand are 'solid'. 

The parts of any matter can be made under special condition to transition from one state into another. So, while we do mention 3 main states of matter, there are infinite phases of matter.

4. What happens when water is poured in a cup with citric acid?
The water parts and the citric acid parts mix. Two colors of Unix cubes can demonstrate this.
In this particular case, the citric acid parts are completely occupying the space between the water molecules. We say that the citric acid has completely dissolved in the water. We observe that the citric acid crystals have completely disappeared.

5. What happens when to a mixture of citric acid crystals and baking soda powder is added water?
Bubbles, fizziness, foam. To show that, cover the beaker with plastic wrap. The plastic wrap will inflate.

6. What happens when citric acid is added to a water solution of red cabbage?
The color of the red cabbage powder water solution is   is purple. When citric acid is added to it, the solution turns red. No bubbles (gas) are released.

7. What happens when baking soda is added to a water solution of red cabbage?
The solution turns blue. No bubbles (gas) are released.

8. What happens when the solutions from step 6 and 7 are mixed?
The solution turns purple. Gas is released. Check by placing plastic wrap over the beaker.

9. Did the result in step 8 surprise you?
a) water+red cabbage parts->purple solution, no gas is released
b) water parts+baking soda parts+citric acid parts->bubbles, gas; colorless solution
c) citric acid+red cabbage+water->solution in which citric acid parts are present (Solution 1)
d) baking soda+red cabbage+water->solution in which baking soda parts are present (Solution 2)
e) Solution 1+Solution 2 = (red cabbage parts+water parts+citric acid parts)+(red cabbage parts+water parts+baking soda parts)->(red cabbage parts+water parts)+(water parts+citric acid parts+baking soda parts)=(purple solution)+(colorless solution+gas)=purple solution+gas

The last step is derived using the postulate of chemistry that atoms and electrons just switch places during chemical reactions. What we observed is what we would expect if the postulates of chemistry were valid.