The Effects of Temperature on Water Absorption in Warblettes

In this experiment, we are going to determine the effect of temperature on water absorption in warblettes.

To complete this experiment, you will need the following:

Procedure

1. Create an ice bath by placing a mixture of water and ice in the 500 ml beaker. Fill approximately 1/2 full.

2. Using a graduated cylinder, pour 50 ml of water into one of the 250 ml beakers. Place the beaker in the ice bath. This will keep the water cold during the experiment. For the purpose of this experiment, it will not be necessary to measure the actual temperature of the water. Our main goal is to compare cold and warm temperatures in general. The water will drop to between 5 and 10 degrees celsius.

3. Using a 50 ml cylinder, add 50 ml of hot tap water to the second 250 ml beaker. The water temperature will be approximately 40 degrees C and will continually cool during the experiment.

4. Add 40 Warblettes to each of the 250 ml beakers. Allow the Warblettes to absorb water for 20 minutes.

5. Take one beaker and pour the remaining water into the graduated cylinder. Measure this amount and subtract from the original 50 ml. This calculation will give you the amount of water absorbed by the Warblettes. Repeat this step for the second beaker.

Result

The warmer temperature water will promote faster growth of the polymer. Compare this to real life applications like:

  • Coffee, tea, sugar, and other solids dissolve faster in hot water.
  • Most bacteria grow best at warmer temperatures (close to human body temperature).
  • Ice on a contusion reduces bruising by slowing blood flow.

Warblettes can be used in many experiments and create interest and excitement while reinforcing scientific principles.

 

Teaching Chemical Changes in the Elementary Classroom

Sodium Bicarbonate, Calcium Chloride and Phenol Red

Let’s go over the procedure first and then we will discuss what is happening.

1. In a quart baggie, place sodium bicarbonate(1 tsp) in one corner and calcium chloride(1 tsp) in the other.
2. Lay the bag on its side and place a small cup (medicine cup size – 1 oz) of phenol red in center of the bag. Be careful not allow the any on the chemicals to mix yet. Seal the bag
3. Gently pour the phenol red where it spills into each corner. Do not mix the two corners yet.
4. Have the students feel each corner and make observations. Continue the observations for a few minutes.
5. Pick the bag up and gently move the bage side to side, mixing the chemicals. What happens?

Explanation

The side of the bag with calcium chloride becomes warm. The calcium chloride dissolves forming calcium and chloride ions. The release of heat (exothermic) is a result of the calcium chloride dissolving and not a chemical reaction.

When the sodium bicarbonate dissolves to form sodium, hydrogen and carbonate. It becomes cool (endothermic). The baking soda absorbs heat in order to dissolve. This is not a chemical change.

When the two sides are mixed, calcium carbonate is formed which is insoluble. Also formed are water and carbon dioxide. The carbon dioxide (gas) causes the bag to inflate. When the carbon dioxide dissolves in the liquid, carbonic acid is formed. This change in pH causes the phenol red to turn yellow. A chemical change has now occurred.

Remember to have the students use all lab safety measures. If the bag becomes over inflated, release some of the gas.

Glacial Heat – Teaching Supersaturated and Supercooled Solutions

Glacial Heat

Glacial Heat

What’s Happening?

Inside the Glacial Heat exists a supersaturated and super-cooled (below its freezing point) solution of sodium acetate and water.This supersaturated solution was created by mixing the salt (sodium acetate) in hot water. Hot liquid will dissolve more salt than a cold one. When this solution is cooled slowly, the salt stays in solution.

CH3COONa.3H2O + Heat -> CH3COO-(aq) + Na+(aq)+3H2O
(Solid) (Liquid)
A small, stainless steel, metal chip provides the “spark”. When the chip is squeezed, a small, single, solid salt molecule is created. This is the seed ,on which, the other salt crystals begin to form. The normal freezing point for sodium acetate is 130 degrees F (54 degrees C). The reaction occurs quickly, with heat being released and the liquid becomes solid (freezes). The heat being released is equal to the freezing point of the solution (54 degrees C). The sodium acetate (a salt) dissolving and freezing in the water is an example of a physical change.

 

How do I Teach With Glacial Heat?

Discuss physical and chemical properties:

Physical properties are observable (color, size, luster and smell) and also include characteristics, such as, freezing point, melting point, malleability, conductivity, volume, mass, weight and length.

Chemical properties are only observable during a chemical reaction and can include flammability or the ability to rust. In each of these examples, a new compound has been formed.

Discuss physical and chemical changes:

Physical changes include ice melting, molding clay, water evaporating, a coke freezing and sugar dissolving in water. In these examples, no chemical changes have occurred and the changes can be reversed.

Chemical changes include metal rusting, lighting a match, milk souring and the stomach digesting food. These changes are not easily reversed. The presence of light, color change, odor, gas production, heat or sound can indicate that a chemical change has taken place.

The Glacial Heat can be boiled (melted) for 7-10 minutes and reused over and over again.

Hydrolysis – The Splitting of Water

See the Oxygen molecules bubble and the indicator turn pink

See the Oxygen molecules bubble and the indicator turn pink

Hydrolysis Water Splitting

Using a 9V battery, 2 electrodes and small gauge wire, you can split water into its component parts. This process is called hydrolysis. We add a small amount of salt to increase the conductivity of the water and an acid/base indicator to visualize the reaction.

The chemical formula of water is H2O. When the electrical current, produced by the battery, passes through the water, the water will split and the two electrodes will bubble. Hydrogen will appear at the cathode and the oxygen at the anode. The acid base indicator around the cathode will turn blue (because the free OH molecules raise the pH) and the area around the anode will turn pink (because the free hydrogen molecules lower the pH).

Looking at the formula for water, there are twice as many hydrogen atoms as oxygen. When hydrolysis occurs, twice as many hydrogen bubbles will be released as oxygen. You can visually see extra bubbles at the point where hydrogen is being released.

Hydrolysis experiments can be quantitative (how much hydrogen and oxygen are released?) or qualitative (can I visually see the reaction taking place?)

Magic Snow

What is Magic Snow?

Magic snow is an absorbent polymer that is safe and non-toxic, it has the ability to expand up to 40 times its original volume. The snow starts out as a simple powder that looks similar to sugar or salt. The magic happens when water or other liquid is introduced to the magic snow, which quickly expands to absorb the liquid.

How is it Used?

Hollywood uses it for special effects, many people use it to decorate for parties, and thanks to its low price you can use magic snow for fun. When using magic snow, use it on a dish, bowl, cup, test tube, or anything else that will help you contain the magic snow. First place the magic snow into the container of your choosing, next sprinkle a small amount of magic snow into the container. Then add a small amount of water and watch it grow. Use more in the following trials once an idea of the amount the magic snow expands is gained.

Example

magic snow

Do not let magic snow into drains or pipes; it will expand causing them to clog. The best way to dispose of magic snow absorbent material is to put it in a plastic bag and then in the trash. Do not rinse the container you use for magic snow creation in the sink, even a little can cause clog. However if you do accidentally clog a drain, a small amount of bleach will clear the drain.