Test Skid #1

Test Skid #2

Meteoric activity increases throughout the night because Bootes continues to rise higher in the sky. But there’s another more significant factor at play here. During the evening hours, we’re on the side of the Earth “facing away” from the direction the meteors are coming and they have to “catch up” to us. But after midnight we’re turned into the direction of the radiant, casing the meteors to slam into the atmosphere at much higher speeds – resulting in many more of them being seen, and those that are seen to generally be brighter and more spectacular. So losing some sleep to stay up late for a meteor watch is definitely well worth it!

But that’s given good sky conditions. For this year’s display, the Full Moon will rise around sunset and dominate the sky all night. While this will wash out many of the fainter meteors, several dozen per hour of the brighter ones should still be visible — especially after midnight. A helpful technique here is that once the Moon has moved into the western sky (again, after midnight) hide it behind your house or other structure, and with your back to it face east toward the radiant. Since meteor watches typically run many hours, reclining on a lawnchair is usually recommended. But on a frigid January night, you may prefere instead to remain standing and keep moving to stay warm!

Observing meteors is basically a naked-eye activity in order to canvass as large an area of the sky as possible. However, the use of your Edmund binoculars is also encouraged for following the fascinating drifting “smoke” trails left by many of the really bright meteors (which themselves will be moving at medium speed — lasting a couple of seconds — and appear bluish in color). Finally, as to the rather strange-sounding name of the Quadrantid shower, it comes from the long-obsolete constellation Quadrans Muralis. This point in the sky where the radiant lies is now part of Bootes itself.

Additional resources: International Meteor Organization 2008 meteor shower calendar

Related Products

• Edmund Scientific astronomy category
• Edmund Scientific telescopes
• Ward’s astronomy lab activities

Guest post: This article originally appeared on the Edmund Scientific site, as part of their Sky Talk series. The article was written by James Mullaney, former assistant editor at Sky & Telescope and author of five books on stargazing. Edmund Scientific has graciously agreed to let us post these articles to provide additional resources for Earth Science and Astronomy educators.

Materials

• Organic alcohols in dropper bottles (see chart below)
• Organic acids in dropper bottles (see chart below)
• Sulfuric acid, H2SO4 (18 M)
• Sodium carbonate, Na2CO3
• Test tubes
• Test tube holder
• Bunsen burner
• or, the Ester Formation Lab Activity

Safety

• Read the MSDS/WHMIS sheets for all chemicals before using them
• Wear chemical safety glasses
• Waft vapors when detecting odors
• Concentrated acids are used

Procedure

1. In a test tube add 15 drops of ethanol to 20 drops of glacial acetic acid.
2. Add one drop of concentrated sulfuric acid.
3. Mix the reactants by gently tapping the test tube.
4. Gently heat the bottom of the test tube for several minutes. Keeping the test tube on a slight angle helps control vapor loss. If the solution starts to boil remove it from the heat.
5. Add a small amount of sodium carbonate to neutralize any excess acid.
6. Carefully smell by wafting. Dilute with water if the smell is to strong.
7. See the chart for more combinations. Use 0.5 g of solid acids such as salicylic acid.

Results
Vary depending on the organic acid and alcohol used (see reference chart below).

Follow-up Teaching Notes:

Ester reference chart

• The concentrated sulfuric acid acts a catalyst and as a dehydrating agent for the condensation reaction between the alcohol and the carboxylic acid.
• When using butyric acid perform the demonstration in a fume hood due to the bad butyric acid odor.

Connections
Organic synthesis, esters, condensation reactions.

Disposal/Clean-up
Dispose of the esters down the drain with lots of water. Check local codes before any disposal activity.

Materials

• Shaving cream
• Marshmallow
• Soda water
• Doll’s head
• Vacuum pump with bell jar

Safety
Ensure there are no cracks in the bell jar

Procedure

1. Fill an empty doll’s head with shaving cream from the neck opening. Ensure openings are present at the eyes and ears.
2. Tape the neck opening closed.
3. Place the Doll’s head in a bell jar connected to vacuum pump.
4. Evacuate the chamber of air.
5. Other items that can be placed in the bell jar include soda water, small balloon, or a marshmallow.

Results
As the surrounding pressure decreases the shaving cream/marshmallow expands.

Follow-up Teaching Notes

• Shaving cream is a foam (type of colloid) that consists of a gas evenly distributed in a liquid.
• As the surrounding pressure is decreased the gas expands in size.

Connections
Gas laws, solubility of gases, decompression sickness, colloids

Extension
Can be related to decompression sickness.

Disposal/Clean-up

• The marshmallow and shaving cream can be disposed of in the garbage.
• The soda water can be washed down the drain.

To construct a dichotomous key, you must first identify and describe a property that some of the objects have but that none of the other objects have. This property may be presented to the user in the form of either a qualitative or quantitative description. Qualitative descriptions concern the physical attributes, or qualities, of the item being classified (e.g., “has blue hair”). Quantitative descriptions concern values that correspond with the item being classified (e.g., “has eight legs”). Often times separating the bigger group is the most difficult part of constructing a key. Obviously, the bigger the group, the greater the variation that is likely to be found in it, and the more exceptions there will be to any definite statement that is made about the group. The next step is to group all the objects displaying that property in one set (couplet) and all of the remaining objects in the another couplet. Some taxonomists use numbers to separate the couplets while others use letters. Also, some taxonomists prefer to place each couplet together, while others may separate couplets. One example of a simple dichotomous key for shapes is shown in Figure 1 below.

1a. The shape consists of four sides…..Go to 2
1b. The shape consists of three sides…..Go to 3
2a. Both pairs of opposite sides are parallel………..B (Parallelogram)
2b. Only one pair of opposite sides are parallel…..D (Trapezoid)
3a. One angle is equal to 90°………………………A (Right triangle)
3b. All angles are less than 90° and equal……….C (Equilateral triangle)

When constructing a dichotomous key, it is important to be as specific as possible so that the user does not become confused. The idea is to word each couplet in such a way that the user will arrive at the correct answer. If the wording leaves too much room for interpretation, the user could easily end up with an erroneous classification. When using a dichotomous key, it is important to consider both choices in the couplet. Jumping to conclusions may lead to the wrong classification of the item. When classifying a living (or once-living) specimen, it is best to study many specimens due to the variation between organisms. This will ensure that your results are representative of the majority.

DID YOU KNOW?

• Dichotomous keys are valuable tools for taxonomists and naturalists. Many related organisms closely resemble one another, and it can be difficult to differentiate between similar species. A properly designed dichotomous key can provide researchers with an easy to use method for identifying species.
• Aristotle (4th century B.C.) was one of the first men to attempt to group organisms based on their form and structure. He grouped animals according to whether they inhabited water, land, or air, and plants by differences in their stems. Linnaeus (18th century) took this classification system further by developing the binomial naming system we use today.
• It is often impossible to determine the species or sub-species of organisms such as plants and small animals or fishes before they reach maturity. Recent biotechnological advances allow scientists to identify organisms early in their development using species-specific molecular markers.

Related Products

• Constructing a Dichotomous Key Lab Activity
• Introduction and Use of Dichotomous Keys Lab Activity
• Concepts of Classification Lab Activity

The kidneys are very important organs within the human body because they are essential to maintaining homeostasis. Humans have two bean-shaped kidneys that are found at the back of the abdominal cavity, one found on each side of the spine. Each kidney is approximately the size of a person’s fist. All the blood in the body must pass through the kidneys. The large amount of blood that is passed through the kidneys allows them to do the following:

• Assist in the regulation of blood pressure
• Stimulate red blood cell production
• Maintain calcium levels in the body
• Regulate the composition of the blood by keeping the pH, concentration of various ions, and the volume of water constant. The kidneys filter wastes (urea, ammonia, salts, drugs, water, and other toxic substances) from the bloodstream in order to keep the blood clean and chemically balanced.

The anatomy of the kidneys provides a greater understanding of the major role they have in maintaining homeostasis within a person’s body (Figure 1).

The renal artery transports blood from the body into the kidney, and the renal vein transports filtered blood back into the body. The light colored outer region is known as the cortex, while the darker inner region is known as the medulla. The pelvis is a flat, funnel-shaped cavity that collects urine in the ureters. Upon closer inspection of these regions in the kidney, thousands of tiny structures, known as nephrons, can be seen. Nephrons, composed of small arteries, are the filtering units of the kidneys. Each kidney contains over one million nephrons, which is a tube closed at one end and open at the other (Figure 2). Nephrons make urine by filtering the blood of its smallest molecules and ions and then reclaiming the needed amounts of useful materials. Surplus or waste molecules and ions are left to flow out as urine.

Filtration begins as blood is carried to a tuft of capillaries known as the glomerulus. The glomerulus filters the blood by hydrostatic blood pressure, forcing the blood through the basement membrane and into the cavity of the glomular capsule, also known as the Bowman’s capsule. Blood cells and proteins too large to be filtered through this membrane remain in the blood. Water, small molecules, and ions filter through the capillary walls into the Bowman’s capsule, which is located at the closed end of the nephron. This fluid is called nephric filtrate. The nephric filtrate collects within the Bowman’s capsule and then flows into the proximal tubule. Here most of the glucose, amino acids, and approximately 60% of the salts are reabsorbed through active transport. As these solutes are removed from the nephric filtrate, a large volume of the water follows through osmosis.

As the remaining filtrate flows into the loop of Henle, it is isotonic to the blood, but while in the loop of Henle, more sodium ions are pumped out into the peritubular capillary network. Since water remains in the loop of Henle, the interstitial fluid in the capillary tubes becomes very hypertonic and the fluid within the loop of Henle becomes hypotonic. In the distal tubes, active transport moves more sodium, but at this point, water also crosses the membrane through osmosis.

After filtrate has passed through the loop of Henle, it enters the collecting tubules, where it then is carried toward a nearby collecting duct. The collecting duct leaves the cortex and descends into the medulla, carrying fluid toward a papillary duct. The filtrate then enters the renal papillae, which are small openings into the renal pelvis. From here, the remaining filtrate, now known as urine, is excreted through the ureters to the bladder, where the urine is stored until it is excreted. The kidneys are able to filter approximately 180 liters of filtrate per day; however, they only excrete 1 to 1.5 liters of urine, conserving the amount of water loss and greatly concentrating the salts and other wastes in the urine.

The function that the kidneys perform is so vital to a human’s survival that total kidney failure can cause a person to die in a very short time. Most kidney diseases attack the nephrons, causing them to lose their filtering capacity. Damage to the nephrons may happen quickly, often as a result of injury or poisoning, or, more commonly, most damage occurs slowly and silently. Years and years may go by before the damage even becomes apparent. The two most common causes of kidney disease are:

• High blood pressure can damage the small blood vessels in the kidney, not allowing for filtration of poisons from the bloodstream.
• Diabetes keeps a person’s body from using sugar as it should. The sugar then stays in the bloodstream instead of breaking down. In turn, it acts like a poison that can damage the nephrons.

Kidney disease cannot be cured. However, it may be possible to make the kidneys last longer if kidney disease is detected in the early stages. Certain precautionary measures that can be taken in these early stages include regularly checking blood pressure, avoiding pain pills that may make kidney disease worse, carefully watching the diet by limiting proteins, salt, and cholesterol, and watching blood sugar levels very closely.

When the kidneys stop working completely, a condition known as uremia becomes apparent. One symptom of uremia is edema, which makes a person’s hands and feet swell. In addition, the body also fills with waste products, which leads to feelings of tiredness and weakness because tissues need clean blood to function properly. If uremia is left untreated, a person may have seizures or enter into a coma that may ultimately result in death. Two methods for treating uremia are dialysis or kidney transplantation.

Fortunately, medical technology has developed a machine, known as dialysis, that can serve as an artificial kidney, filtering out wastes and replenishing the body with “clean” blood. The two major forms of dialysis are hemodialysis and peritoneal dialysis. In hemodialysis, blood filled with waste products is sent through a machine that filters away waste products and the clean blood is returned to the body. Hemodialysis is usually performed at a dialysis center three times per week for 3 to 4 hours. In peritoneal dialysis, a fluid, called dialysate, is put in your abdomen. Dialysate captures the waste products from the blood. After a few hours, the dialysate containing the wastes is drained from the abdomen. Then, a fresh bag of dailysate is dripped into the abdomen. Patients can learn to do this themselves without going to a doctor’s office each time. On average, patients change dialysate four times a day.

With only a few hours of dialysis a week, a person may live for years without functioning kidneys while they wait for a suitable kidney transplant to become available. A donated kidney may come from an anonymous donor who has recently died or from a living person, usually a relative. It is essential that a person receive a kidney that is a good match for their body because then it is less likely that the immune system will reject it. Scientists have also developed special drugs that can trick a person’s immune system to help it accept a transplanted kidney.

DID YOU KNOW?

• The kidneys represent on 0.5% of the total weight of a body, but receive 20-25% of the total arterial blood pumped by the heart.
• The rate of filtration is approximately 125 ml/min. or 45 gallons (180 liters) per day. Considering that you have 7 to 8 liters of blood in your body, this means that your entire blood volume gets filtered approximately 20-25 times each day.
• Each kidney contains over one million nephrons.
• The right kidney is slightly lower than the left.
• Each kidney weighs about 113 – 170 grams and is about 11.4 cm long, 6 cm wide, and 2.5 cm thick.
• The first workable artificial kidney was developed during World War II in 1944 by Dr. William Kolff who was living in Holland.
• According to the National Kidney Foundation, more than 370,000 Americans are being treated with dialysis or kidney transplantation for kidney failure. Nearly 12 million Americans may be at risk for chronic kidney disease.
• The use of a dialysis machine is suggested when a patient’s blood urea nitrogen value exceeds 100 mg/dl (the normal value is 30 mg/dl).

Related Products

• Kidney Dialysis Simulation Lab Activity
• Basic Kidney Model
• Kidney Nephron Model
• Glomerulus and Sections of Tubules Model
• 3B® Kidney Model

You will need:

• Baking soda
• Vinegar
• A “volcano” –a container to hold the reaction

(Note: a fun related art project is to create and paint your own volcano out of Plaster of Paris or paper-maché with a built-in well to hold the reagents.)

Safety Tips:

Provide paper towels to clean up the resulting eruption – it can be a fizzy mess. The lab’s reagents are harmless, but you should take care to avoid contact with your eyes.

Experiment Steps:

1. Place some baking soda into your container.
2. Pour in some vinegar.
3. Watch for the resulting volcanic eruption.

Explanation:

The sodium bicarbonate in baking soda is neutralized by the acetic acid in vinegar, and the reaction causes carbon dioxide to be released as one of the by-products. The carbon dioxide is the cause of the fizzing and crackling sounds heard during the eruption.

The reaction you witnessed was this:
NaHCO₃ + CH₃COOH »» CO₂ + H₂O + Na (aq) + CH₃COO (aq)

Related Products

For more at home exploration of acid-base reactions, try WARD’S lab activities:

• Patriotic Colors Activity (36 V 0001)
• Red Cabbage pH Indicator Kit (36 V 6974)

If you would like to learn more about volcanoes, see WARD’S videos and models:

• Our Amazing Volcanoes Model Kit (80 V 0241)
• GeoBlox Volcano Block Models (80 V 0210)
• Volcanoes CD-ROM (74 V 6252)
• In the Path of a Killer Volcano Video (193 V 0355)

Materials

• Rubbing alcohol (70% isopropyl alcohol)
• 19 L plastic water bottle (water cooler jug)
• Meter stick with candle on the end (or barbeque lighter)
• Safety shield
• 50 mL graduated cylinder

Safety and Disposal

• Read the MSDS/WHMIS sheets for all chemicals before using them
• Wear chemical safety glasses
• Safety shield should be between the bottle and the audience
• Ensure you are one meter away when using the meter stick/candle to start the reaction
• Never heat the bottle above room temperature prior to use
• Never flush the bottle with oxygen prior to use

Procedure

1. Add 50 mL of rubbing alcohol to an empty 19 L plastic water bottle.
2. Swirl the alcohol around to coat the inside of the container.
3. Pour out the excess alcohol and remove it from the demonstration area.
4. Place bottle behind a safety shield.
5. Dim the lights.
6. Light a candle on the end of meter stick and then place the flame over the mouth of the bottle.

Results

• A blue, horizontal circle of flame should form and move from the top of the bottle to the bottom.
• A “whoosh” sound is heard.

Follow-up Teaching Notes
A “whoosh” sound is generated as the gases in the bottle expand out of the container as they are heated from the rapid exothermic combustion reaction.

Concept
combustion, expansion of gases.

Extension

• Place the palm of your hand over opening of the bottle after the combustion ends, as the bottle cools the resulting pressure decrease causes the bottle to stick to your hand.
• A second “whoosh” may be heard as air rushes back into the bottle as you remove your hand.

Disposal/Clean-up
The plastic container can be stored for reuse if the are no visible signs of stress or damage to the container.

Materials

• Copper (II) chloride, CuCl2 (1.0 M solution)
• 2 ea. graphite electrodes
• Power source (15V max.)
• Volt meter
• Electrical leads (with Alligator Clips)
• 250 mL beaker
• 100 mL graduated cylinder

Safety

• Read the MSDS/WHMIS sheets for all chemicals before using them
• Wear chemical safety glasses
• Ensure the electrodes do not touch
• The chlorine gas generated is poisonous, ensure area is well ventilated (use a fume hood)
• Clean the graphite electrodes in a fume hood due to the toxic gas generated when using nitric acid to remove the copper

Procedure

1. Add 100 mL 1.0 M copper (II) chloride solution to a 250 mL beaker.
2. Immerse a pair of clean graphite electrodes into the concentrated aqueous solution. (Can be done on a glass petri dish on the overhead).
3. Ensuring that electrodes do not touch, connecting them to a variable voltage DC power source.
4. Slowly raise the voltage.
5. Observe the voltage reading at which the reaction could be detected.
6. Leave the power on for a couple of minutes and then disconnect the power source and connect the electrodes to voltmeter.
7. Observe the voltage reading. If the voltage is zero switch the leads from the graphite electrodes on the voltmeter.
8. Remove the electrodes from the solution and observe any discoloration and odor.

Results

• When the power source is turned on and the voltage is increased copper metal will be plated onto the negative electrode and chlorine gas will be generated at the positive electrode.
• When the power source is removed a voltage is generated as the reverse reaction occurs.

Follow-up Teaching Notes

• When the graphite electrodes are connected to the power source, copper ions will be reduced to copper metal on the electrode connected to the negative terminal and chloride ions will be oxidized to chlorine gas on the other electrode.
• When the power source is used, an electrolytic cell is produced.
• After copper metal and chlorine gas are generated and the power source is disconnected a voltaic (galvanic) cell is made.
• The copper can be cleaned off the electrodes with concentrated nitric acid.

Connections
Electrolytic/ voltaic cells (electrochemical cells), spontaneous/non-spontaneous reactions.

Disposal/Clean-up
The copper (II) chloride solution can be stored in a sealed container for later reuse or it can be placed in the science department’s heavy metal waste container for proper disposal.

Materials

• Magnesium strip or ribbon
• Copper strip
• Orange juice
• Steel wool (not a soap pad)
• Electrical leads (with Alligator Clips)
• Battery powered clock (variety that requires a single 1.5 V AA battery)
• 250 mL beaker

Safety
Do not taste the orange juice

Procedure

1. Clean a strip of magnesium and a strip of copper with steel wool.
2. Pour ~200 mL of orange juice into a 250 mL beaker.
3. Connect an electrical lead to one end of the magnesium strip and submerge the other end in the orange juice. (You could tape it to the side of the beaker).
4. Connect the second electrical lead to one end of the copper strip and submerge the other end in the orange juice on opposite side of the beaker.
5. Connect the other ends of the electrical leads to the battery compartment of a clock that would normally run on a single AA battery.
6. If the clock does not run reverse the electrical leads in the battery compartment.

Results
The second hand will begin to move upon connection to the electrical leads.

Follow-up Teaching Notes

• A voltaic (galvanic) cell is created with the magnesium the anode and the copper the cathode.
• The components of the cell can be changed to explore the key components (i.e. change one of the metal electrodes) of a voltaic (galvanic) cell.

Connections
Electrochemistry, redox reactions, voltaic (galvanic) cells.

Extension
Connect two or more cells in series to generate a higher voltage.

Disposal/Clean-up

• The orange juice can be disposed of down the drain.
• The metal strips (electrodes) can be cleaned and reused.