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.

Why are Photovoltaic Cells Black?

The dark color reduces the amount of photons reflected. Photons that are not absorbed by the panel cannot be used to produce electricity.

Solar Science Kit

What are Photovoltaic Cells Made From?

Silicon is the major material in the cells. Pure silicon crystals are poor conductors of electricity. Other elements are added to the silicon, such as, phosphorus and boron. When the energy from the sun hits the cell, the electrons in the elements begin to move around. The sun causes the panel to have a positive and negative side. This electrical difference causes electrons to flow through a diode.

What Factors Affect the Production of a Solar Cell?

The factors that most affect the production of a solar cells are the angle of the panel in relation to the sun, the peak wattage, the light intensity and the hours of sun exposure.

How is Wattage (or Power) Calculated?

The formula for power is   Power=Current X Voltage. Power is measured in watts, current in amperes and voltage in volts.

The Solar Science Kit has a small motor, photovoltaic cell and disc that works well in demonstrating this in a classroom or home setting.

What is a Generator?

When a magnet moves toward a metal object, the electrons in the metal move. As a result, when a magnet moves near a copper wire, electrons in the copper move. Generators use this principle to convert mechanical energy (the rotation of a wire coil,or rotor around a magnet) into an electrical current (electrons flowing through the wire). A motor performs the opposite function by converting electrical energy into mechanical energy. For the most part, all generators work the same. The item that separates them is, “What turns the rotor?”

Windmill Generator Kit

 Energy Conversion in a Windmill 

 Obviously, in a windmill, the wind is rotating the wire coil around the magnet. This generator is taking the kinetic energy from the wind and converting it to electrical energy.

Windmills are rated based on output power (watts), working voltage (volts), start up windspeed (mph), survival wind speed (mph), rated rotation of the blades (rpm) and the diameter of the blades  (also called the rotor). In general, the larger the rotor diameter the more wind that is intercepted and the more electricity produced. There are do-it-yourself plans available for building your own windmill. No waste or pollution is produced during this process.

When discussing this in the classroom or entertaining your children on the weekend, there are some small demonstration kits available. The Windmill Generator from 4M Kidz Labz TM is an excellent activity.

Nitrogen is found throughout the soils and atmosphere in many different, organic and inorganic, forms. The Nitrogen Cycle is the process by which atmospheric nitrogen  enters the soil, is transformed by microbes, and re-enters the atmosphere (volatilization) and plants (assimilation).

How Does Nitrogen Enter the Soil?

Before nitrogen can be used by plants, it must enter the soil.  Atmospheric nitrogen is forced to the ground by rainfall. Also, urine, solid and liquid waste from living organisms and living organisms that have died are deomposed by bacteria and fungi.  The nitrogen from these sources then enter the soil. Commercial fertilizers are another source of nitrogen.

What Happens to Nitrogen in the Soil?

Plants cannot use organic nitrogen. Bacteria and fungi are needed to transform this unusable organic nitrogen into a usable form.  Although most nitrogen fixation is completed by bacteria, some is accomplished through lightning strikes. Since ammonia is fatal to most plants, bacteria convert this ammonia (NH4) into nitrates (NO3) and nitrites (NO2). At this time, the nitrogen can be assimilated into the plant, leached into the ground water or be transformed into a gas and re-enter the air.

In very wet soils, the oxygen content is low. The bacteria in these soils take the oxygen out of the nitrates (NO3) and produce nitrogen gas. This process is call denitrification.  Through a process called volatilization, the gas re-enters the atmosphere.

Dissecting owl pellets is a fun and educational method of analyzing predator / prey relationships and for learning basic dissection techniques.

What is an Owl Pellet?

An owl pellet is the portion of an owl’s prey that has not been digested. Owl’s swallow their prey whole (they don’t have teeth to chew) and the feather’s, fur, bones and other undigestible parts are regurgitated by the owl.

How Does the Owl Pellet Form?

When the prey is swallowed, it travels through the esophagus and into the first part of the stomach, the proventriculus. Unlike other birds, the owl does not have a crop to store the food. As a result, the prey enters directly into the digestive tract. This part of the stomach has enzymes and acids (like our stomachs) to aid in digestion. From the proventriculus, the food travels to the second part of the stomach, the gizzard. The gizzard is a muscular organ that grinds the food and ”filters” undigestible parts from traveling into the intestines.

The pellet is formed from the hair, bones or feathers that are left in the gizzard. The pellet will take several hours to form and several more before it is regurgitated. The owl cannot eat again until this pellet is expelled.

Does the Regurgitation of the Pellet Benefit the Owl?

Yes.  Many scientists believe that this regurgitation of the pellet keeps the upper digestive tract clean.

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?)

Keep the lid over your plate to prevent contamination.

All living organisms require energy. They can get their energy from multiple sources: organic chemicals(carbon containing compounds), inorganic chemicals and light. Bacteria use organic chemicals, such as, sugars, starch, protiens and fats to grow. Bacteria are called heterotrophs.

Most bacteria grow best at normal, human body temperature (98-99 degrees F). When growing the bacteria, incubate at a temperature as close to this as possible. The bacteria will grow slower at lower temperatures.

Aseptic technique is the process of growing and transferring bacteria without contaminating the culture by touching or breathing on the sample.

Nutrient agar is a general purpose prepared media and grows many types of bacteria and fungi. If you have a specific bacteria culture, you can spread the bacteria on the plate using a sterile swab or innoculating loop. The bacteria will grow and become visible in 24-48 hrs. If you would like to determine the types of bacteria growing on a sink, chair, table or other areas, a sterile swab can be used to rub across the area you would like to test. After the sample is taken, you can transfer the bacteria to the nutrient agar plate by swiping the swab across the surface of the agar plate. After 24-48 hrs, you may find many, different looking colonies growing on the nutrient agar plate. Each type of bacteria look a little different (color, shape, size) when they grow.

Crayfish are marvelous classroom organisms. They are exciting and easy to care for. Through close observation, students can learn interesting details about animal structures while developing sensitivity to the needs of living organisms.

About
Crayfish are also known as crawfish, crawdads, mudbugs, and yabbies; they resemble and are related to lobsters. Crayfish most commonly live in freshwater, only a few have the ability to survive in salt water. There are over 500 different species of crawfish in the world and more than half of them are located in North America. Specifically, Louisiana produces 90% of the world’s crayfish for consumption as food.

Care
To keep your pet crayfish comfortable you will need to keep it in a freshwater aquarium, a fish tank will work just fine. Make sure to cover any holes in the lid of the tank to keep your crayfish from escaping. Feeding your crayfish is simple; many common fish foods will work. Pet crayfish will eat shrimp pellets, vegetables, fish food, algae wafers, goldfish, and minnows. Be careful which fish, if any, you put in the aquarium with your pet crawdad because they will attack and eat fish if they feel threatened or if they appear to be an easy snack. When using a prepared food, do not overfeed. The excess food will spoil the water.

Crayfish from the wild may have mud on their swimmerettes. The crayfish need to be purged (placed in clean, dechlorinated water) to remove the mud. Depending on how much mud is present, several water changes may be necessary.

Crayfish like to have a place to hide. The crayfish will molt, shed it’s exoskeleton. During the few hours after the molt, the crayfish has a soft exoskeleton and is vulnerable to predators. The larger the crayfish grows, the longer the time is in between molts. Crayfish have gills for breathing underwater, but can also breathe air.

Ant History

Ants are insects that evolved from wasp-like creatures over 100 million years ago. Today there are over 12,000 species of ants that have been classified.

Ants form colonies that range in population from a few dozen living in small natural cavities to millions that live in larger structures they build in the ground. The colonies consist of three types of ants. Sterile, wingless females, fertile males, and fertile females referred to as queens. The sterile female ants serve as soldiers or workers in the colony.

Ants work together in colonies to build their habitat and recreate. The process can be fascinating to watch for children and adults alike. Due to the fact that most ant colony behavior takes place beneath the ground, humans must use ant habitats or ant farms to observe ant colony behavior.

Ant Farming

The ant farm is designed to study ant and ant colony behavior by offering a great observation tool for the classroom or just for fun. Myrmecologists study ant behavior, and with an ant farm you can take a look into the world of myrmecology (the study of ants).

Ant Farm Types

The Ant Farm by Uncle Milton is a classic ant farm that has a green farm scene with a clear viewing pane surrounded by a green frame. The farm is usually filled with sand, dirt, or other media. These ant farms have a low price point making them accessible to classrooms and families of all budgets. In order to properly care for your ants, you will need to open the ant farm and make sure the ants have food and water. The down side is that this increases the chances of the ants getting out of the farm and into places you do not want them.

In recent years the Ant Farm has been modernized with improvements to visibility. A modern alternative ant farm is the AntWorks Illuminated Habitat

AntWorks Illuminated Habitat

The AntWorks ant farm is completely see through thanks to a gel that NASA developed when studying ants tunneling at zero gravity. The gel holds nutrition and water so that you do not have to provide the ants with nourishment. The AntWorks Illuminated Habitat is available with either red, green, or blue gel. The setup also includes LED lighting in the base so that you can view the ants at night. All of this is housed in a tightly sealed 6.5L x 6.0W x 1.25D clear acrylic habitat to minimize ants escaping into your house, lab, or classroom.

Set Up

Set up of the green AntWorks Illuminated ant farm was easy using the provided instruction manual. After assembling it and testing the LED lights the next step was to go out and find some ants. There are two options for getting your ants, you can either send in the coupon provided with the kit or find your own ants. After finding the ants, they were put into the ant farm which was covered with a towel for 3 days to allow the ants to get used to their new home. After adjusting to life on the ant farm the ants have created a spectacular tunnel system that looks even better in the dark with the LED lights on. They are fascinating creatures to watch and learn from.

For more information, Wikipedia has in depth information about insects including ants . You can always call Heath Scientific as well.

In a previous post on warblettes, we conducted a small experiment demonstrating the absorption characteristics of warblettes.   There is a small summary below that you can use as a refresher, or you can view the actual warblette experiment.

Warblettes Lab Activity

As mentioned in the previous post, warblettes are co-polymers that absorb up to 200 times their volume in water.  Warblettes are perfect for science fair experiments, in the classroom, or just as a fun activity for your family. Warblettes, which are sometimes referred to as water marbles, are non-toxic and come in clear, red, blue, green, and yellow colors.

The basic absorption experiment we posted on warblette absorption is a simple experiment that uses household objects.  Warblettes can be used for much deeper science and educational learning.  Heath Scientific has created a lab manual for this purpose.

The warblette lab activity book has activities for every age student. There are 13 activities ranging from math and graphing to cellular biology. You can use warblettes to demonstrate potential and kinetic energy, change over time (graphing), man-made and natural polymers, and light refraction. The labs include explanations and procedures. If needed, modify the activities to fit your students abilities or needs.

The Labs Cover:

1.) Calculating Volume – Math
2.) Observation Skills
3.) Polymers and Water Absorbtion
4.) Absorption of Household Liquids
5.) Water Absorption and Time
6.) Water Absorption and Temperature
7.) Advanced Measurement – Volume, Calipers, Averaging, and Reading Charts
8.) Graphing – Line Graph
9.) Potential Energy – Comparing Diameter to Rolling Distance
10.) Varying the Height of an Inclined Plane
11.) The Effects of Acidity on Water Absorbtion
12.) Light Refraction
13.) Density

Both the warblettes and the lab activity book are available at Heath Scientific, which has been providing educational supplies for over 20 years.