Next Quiz is Friday, May 9 on BACTERIA. Here's what you need to know!
Bacteria is the smallest living things on Earth.
The most common shapes of bacterium is rod-shaped (Bacillus) and spiral-shaped (Spirilla).
Ancient bacterium breathed methane and CO2...they are called "anerarobic" creatures.
The first plant life on Earth was a bacteria called "Blue-Green Algae" which, through photosynthesis, helped produce Oxygen!
The primary difference between a bacterium cell and a human cell, is that bacteria have a hard cell wall while a human's is a porous membrane.
An "Endospore" is a genetic "seed" of a bacteria located in the nucleus that can survive extreme conditions for thousands of year.
Bacteria reproduce in different ways, binary fission, asexually, and conjugation.
Bacteria move by small 'whip-like' flagella. More than one is called flagellum.
Bacteria who need to find their own food are called "heterotrophs."
A gaseous by-product of bacteria and good evidence that bacteria is present is the production of methane gas.
"Decomposer" bacteria recycle dead material into compost ready to help plants to grow.
Bacteria can be found nearly EVERYWHERE!
NEXT QUIZ IS FRIDAY, April 11th
on Early Astronomy. Pick up a study guide and reading at the front office!
It's Greek to Me
Use the Greek Prefix and Suffix handout (given out in class or get a copy from the front office!) and a scientific reading entitled "Extremely Exciting Extremophiles." Go over the pre and suffix list. Notice anything about these words? Yep. When they are put together, they make words with meaning. Now choose some of your favorite combinations and make up five words. Be sure to tell me their meanings according to the handout. IF you find some real English words to make from the list, go for it! Now read the handout about "Extremophiles" (which is a Greek word!). Notice how many Greek words are used in this reading about microscopic creatures that love living in extreme conditions. On the back of the reading is a list of Greek scientific words. Make-up five words from this list as well and give me the meaning. So...you should have a sheet of paper with five words from the Greek pre and suffix handout and five words from the reading. REASON WE DO THESE THINGS:
This lesson focuses on the root words of our language especially language used in science. IF you know what some of these words mean, you can "break down" big, complicated words for more easily understood meaning. Knowing some Latin and/or Greek can only do us good! And remember, "Ubi dubi sub ubi."
Chemistry Quiz #1
Mass and weight are two different things. Weight can change depending on gravity. Mass remains constant.
A liquid turning to gas is called evaporation. A gas to liquid is condensation.
A solid to liquid is called melting.
Atoms have particles that are electrically charged and neutrons which are neutrally charged.
An Atom with an extra neutron is called an isotope.
Horizontal rows on the Periodic Table are called periods.
Vertical columns on the Periodic Table are called groups.
YOU MUST BE ABLE TO USE A PERIODIC TABLE TO FIND ELEMENTS, ATOMIC NUMBER, ATOMIC MASS, ETC.
For example:
Two elements on the Periodic Table have 30 neutrons. Which are they?
What is the only metal on the Table that is liquid at room temperature?
Questions from "Penny Lab" and "Wood Block Density Lab" will be on the test as well.
To find volume of a solid, multiply the length by the width and the depth.
To find density, use the equation D = M/V.
Good luck!
OHM's LAW
ALL conductive material has some resistance to the flow of electrons through it. George Ohm discovered the relationship between current, votage, and resistance. This relationship is expressed in the equation I = V/R
I = current which is measured in amps
V = voltage
R = resistance which is measured in Ohms
To find a missing variable, do the inverse operation. Here are some examples:
V = I x R, R = V/I, and I = V/R
Here are some problems I would like you to do. Bring it with you upon your return or e-mail the answers to me.
1. Find the resistance of an object of a voltage of 10 V produces a current of 0.5 I.
2. Find the current produced if a voltage of 36 V is applioed to a resistance of 4 Ohms.
3. The current in a wire is 7.5 amps and the resistance is 4 ohms, what is the voltage?
Magnetism Study Guide
All magnets have 3 things in common; north and south poles, a magnetic field, and they exert a force.
A "magnetic domain" is the regiion of a magnet where all the atoms have aligned themselves in perfect uniformity. Scientists believe this is what gives a material its magnetic force.
Most magnets are made of "ferro" metals which include iron, nickel, and cobalt.
You can 'rearrange' the domains of a metal by gently rubbing it in the same direction against a magnet. The atoms in the metal get lined up according to their individual poles and form a domain.
Static and magnetism exhibit some of the same forces including likes repelling and opposites attracting.
The Earth's core is made of an iron/nickel composite which is spinning. This creates friction which in turn produces heat and static electricity.
A Danish scientist named Orestaad was the first to report the discovery that an electrical field will interfere with a magnetic field. This led to the invention of generators and other components of modern electrical production.
An electromagnet is an iron core wrapped by a copper wire which is charged by electricity. This produces a magnetic force that can be increased by increasing the amount of wraps and/or the amount of electrical energy.
An electric motor converts elelctriecal energhy to kinetic, or mechanical energy. A lightbulb converts electrical energy into light energy. A blow dryer converts electrical to thermal energy.
The Law of Conservation of Energy says that energy cannot be created or destroyed, it can only change form.
Notes for movie “Magnetic Storm” from Discovery Channel. Shown in class 10/24 and 10/25 Make-up showing is on Wednesday, 10/31 during Focus.
The Core of Earth:
One Billion, Trillion tons of molten iron/nickel.
It is spinning faster than the outside of the earth’s surface (refer back to Inertia Lab and the spinning raw egg)
This spinning creates friction.
Friction creates heat and electromagnetic field.
The electromagnetic field exits the Earth from the South pole, surrounds the Earth with the electromagnetic field and enters at the North pole.
Mars:
Evidence shows that Mars had water and an electromagnetic field much like Earths that was at one time lost.
Mars used to be much like Earth, however, around 4 billion years ago, a magnetic decline occurred.
The field failed and the solar winds carried away the atmosphere and water off the dead planet. (Earth was formed @ 4 billion years ago…water from Mars?)
Use Mars as a model of what could happen to the Earth.
Clay Pottery:
Ancient clay pots are like a ‘magnetic recorder’
Clay contains magnetite.
Magnetite aligns to the Earth’s magnetic field.
After it is fired, the magnetite realigns with the Earths magnetic poles and magnetizes the pot.
Millions of tiny magnets all point in the same direction and is locked in showing how strong and the direction of the Earth’s magnetic field.
Studies of ancient ceramics show a dramatic decline in the magnetic field in the past 300 years.
Rate of decline is increasing (@ 10% decrease in the past 300 years)
This is the greatest decline rate the past 5,000 years.
Proof from the lab:
Theory is that fluid movement of the core creates an electrical current which in turn creates magnetic field, which give rise to more hot fluid movement which give rise to more current and so on. Feedback loop. “Electrodynamo Theory”
Scientists study how the core works in the lab by using models and computer models.
Sodium is put in constant motion by using a magnet.
If liquid cools, it will slow down reducing the current and fields.
Mars is too cold to sustain a molten liquid core.
Earths core is cooling at around 100 degrees F per billion year.
It is believed that the Earth can sustain the internal dynamo for billions of years.
Yet the magnetic decline data shows that the decline is going on much faster than cooling would indicate.
Proof from Hawaii:
Lava record that stretches back millions of years.
Lava contains magnetic material from the Earths core. (magma)
Lava cools quickly, locking magnetite which is aligned to the Earth’s poles and shows the magnetic field at the time of that particular eruption.
About 50 years ago, it was discovered that ancient lava samples show that the Earth’s poles have ‘switched’ in the past.
This theory was resisted and it took over 50 years for scientists to accept the theory as fact.
Shows many fluctuations of magnetic strength AND proof that the poles have switched (180 degree) in the past.
Last pole switch occurred @ 700,000 years ago.
Trends indicates that reversals begin occurring around one every 200,000 years.
Computer Simulation Proof:
Simulations of core spinning show that reversals take a long time to occur.
Shows that ‘patches’ of magnetic anomalies occur on the Earth’s hemisphere.
Reverse polarity seems to occur gradually as these ‘patches’ link up causing the dipolar magnetic reversal.
This seems to occur naturally and the simulation decline seems to mirror ‘real world’ effects.
Failure only occurs when the core (fluid) stops spinning.
Proof from Steen’s Mountain in Oregon
A 16 million year old record of lava flows from volcanoes.
One lave flow shows the magnetic field was in flux (movement) while the lava was cooling!
Proof from Naval Records:
18th and 19th sailors (Captain James Cook) kept exact records of the “Angle of Variation”
Obsessed by direction and the differences between True North and Magnetic North.
This very accurate records indicate that magnetic north ‘wobbles’ about and has changed over the past 300 years.
Big changes over the South Atlantic. Called the ‘South Atlantic Anomaly,’ it is an area of magnetic ‘reverse flux.’
Effects:
Compasses would not work correctly.
GPS would not work.
Communication satellites
Multiple magnetic poles would appear.
Migratory animals would be affected
Implications of Magnetosphere weakening. (10 to 100 times weaker than what it is today)
If the magnetosphere decreases, exposure to cosmic radiation could double or more.
Indications that this period could last for centuries.
Increase levels of skin cancer etc.
Data proves that the magnetosphere will regenerate.
Lesson 1: Newton's First Law of Motion
Newton's First Law
Isaac Newton (a 17th century scientist) put forth a variety of laws which explain why objects move (or don't move) as they do. These three laws have become known as Newton's three laws of motion. The focus of Lesson 1 is Newton's first law of motion - sometimes referred to as the law of inertia.
Newton's first law of motion is often stated as
An object at rest tends to stay at rest and an object in motion tends to stay in motion with the same speed and in the same direction unless acted upon by an unbalanced force.
There are two parts to this statement - one which predicts the behavior of stationary objects and the other which predicts the behavior of moving objects. The two parts are summarized in the following diagram.
The behavior of all objects can be described by saying that objects tend to "keep on doing what they're doing" (unless acted upon by an unbalanced force). If at rest, they will continue in this same state of rest. If in motion with an eastward velocity of 5 m/s, they will continue in this same state of motion (5 m/s, East). If in motion with a leftward velocity of 2 m/s, they will continue in this same state of motion (2 m/s, left). The state of motion of an object is maintained as long as the object is not acted upon by an unbalanced force. All objects resist changes in their state of motion - they tend to "keep on doing what they're doing."
Suppose that you filled a baking dish to the rim with water and walked around an oval track making an attempt to complete a lap in the least amount of time. The water would have a tendency to spill from the container during specific locations on the track. In general the water spilled when:
- the container was at rest and you attempted to move it
- the container was in motion and you attempted to stop it
- the container was moving in one direction and you attempted to change its direction.
The water spills whenever the state of motion of the container is changed. The water resisted this change in its own state of motion. The water tended to "keep on doing what it was doing." The container was moved from rest to a high speed at the starting line; the water remained at rest and spilled onto the table. The container was stopped near the finish line; the water kept moving and spilled over container's leading edge. The container was forced to move in a different direction to make it around a curve; the water kept moving in the same direction and spilled over its edge. The behavior of the water during the lap around the track can be explained by Newton's first law of motion.
Everyday Applications of Newton's First Law
There are many applications of Newton's first law of motion. Consider some of your experiences in an automobile. Have you ever observed the behavior of coffee in a coffee cup filled to the rim while starting a car from rest or while bringing a car to rest from a state of motion? Coffee tends to "keep on doing what it is doing." When you accelerate a car from rest, the road provides an unbalanced force on the spinning wheels to push the car forward; yet the coffee (which was at rest) wants to stay at rest. While the car accelerates forward, the coffee remains in the same position; subsequently, the car accelerates out from under the coffee and the coffee spills in your lap. On the other hand, when braking from a state of motion the coffee continues forward with the same speed and in the same direction, ultimately hitting the windshield or the dash. Coffee in motion tends to stay in motion.
Have you ever experienced inertia (resisting changes in your state of motion) in an automobile while it is braking to a stop? The force of the road on the locked wheels provides the unbalanced force to change the car's state of motion, yet there is no unbalanced force to change your own state of motion. Thus, you continue in motion, sliding along the seat in forward motion. A person in motion tends to stay in motion with the same speed and in the same direction ... unless acted upon by the unbalanced force of a seat belt. Yes! Seat belts are used to provide safety for passengers whose motion is governed by Newton's laws. The seat belt provides the unbalanced force which brings you from a state of motion to a state of rest. Perhaps you could speculate what would occur when no seat belt is used.
There are many more applications of Newton's first law of motion. Several applications are listed below. Perhaps you could think about the law of inertia and provide explanations for each application.
- Blood rushes from your head to your feet while quickly stopping when riding on a descending elevator.
- The head of a hammer can be tightened onto the wooden handle by banging the bottom of the handle against a hard surface.
- A brick is painlessly broken over the hand of a physics teacher by slamming it with a hammer. (CAUTION: do not attempt this at home!)
- To dislodge ketchup from the bottom of a ketchup bottle, it is often turned upside down and thrusted downward at high speeds and then abruptly halted.
- Headrests are placed in cars to prevent whiplash injuries during rear-end collisions.
- While riding a skateboard (or wagon or bicycle), you fly forward off the board when hitting a curb or rock or other object which abruptly halts the motion of the skateboard.
Try This At Home |
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 Acquire a metal coat hanger for which you have permission to destroy. Pull the coat hanger apart. Using duct tape, attach two tennis balls to opposite ends of the coat hanger as shown in the diagram at the right. Bend the hanger so that there is a flat part which balances on the head of a person. The ends of the hanger with the tennis balls should hang low (below the balancing point). Place the hanger on your head and balance it. Then quickly spin in a circle. What do the tennis balls do?
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Newton's Second Law
Newton's first law of motion predicts the behavior of objects for which all existing forces are balanced. The first law - sometimes referred to as the law of inertia - states that if the forces acting upon an object are balanced, then the acceleration of that object will be 0 m/s/s. Objects at equilibrium (the condition in which all forces balance) will not accelerate. According to Newton, an object will only accelerate if there is a net or unbalanced force acting upon it. The presence of an unbalanced force will accelerate an object - changing either its speed, its direction, or both its speed and direction.
Newton's second law of motion pertains to the behavior of objects for which all existing forces are not balanced. The second law states that the acceleration of an object is dependent upon two variables - the net force acting upon the object and the mass of the object. The acceleration of an object depends directly upon the net force acting upon the object, and inversely upon the mass of the object. As the force acting upon an object is increased, the acceleration of the object is increased. As the mass of an object is increased, the acceleration of the object is decreased.
Newton's second law of motion can be formally stated as follows:
The acceleration of an object as produced by a net force is directly proportional to the magnitude of the net force, in the same direction as the net force, and inversely proportional to the mass of the object.
This verbal statement can be expressed in equation form as follows:
a = Fnet / m
The above equation is often rearranged to a more familiar form as shown below. The net force is equated to the product of the mass times the acceleration.
Fnet = m * a
In this entire discussion, the emphasis has been on the net force. The acceleration is directly proportional to the net force; the net force equals mass times acceleration; the acceleration in the same direction as the net force; an acceleration is produced by a net force. The NET FORCE. It is important to remember this distinction. Do not use the value of merely "any 'ole force" in the above equation. It is the net force which is related to acceleration. As discussed in an earlier lesson, the net force is the vector sum of all the forces. If all the individual forces acting upon an object are known, then the net force can be determined. If necessary, review this principle by returning to the practice questions in Lesson 2.
Consistent with the above equation, a unit of force is equal to a unit of mass times a unit of acceleration. By substituting standard metric units for force, mass, and acceleration into the above equation, the following unit equivalency can be written.
The definition of the standard metric unit of force is stated by the above equation. One Newton is defined as the amount of force required to give a 1-kg mass an acceleration of 1 m/s/s.
Furthermore, the qualitative relationship between mass and acceleration can be seen by a comparison of the numerical values in the above table. Observe from rows 2 and 3 that a doubling of the mass results in a halving of the acceleration (if force is held constant). And similarly, rows 4 and 5 show that a halving of the mass results in a doubling of the acceleration (if force is held constant). Acceleration is inversely proportional to mass.
An equation such as Fnet = m*a can be a guide to thinking about how a variation in one quantity might effect another quantity. Whatever alteration is made of the net force, the same change will occur with the acceleration. Double, triple or quadruple the net force, and the acceleration will do the same. On the other hand, whatever alteration is made of the mass, the opposite or inverse change will occur with the acceleration. Double, triple or quadruple the mass, and the acceleration will be one-half, one-third or one-fourth its original value.
Newton's Third Law
A force is a push or a pull upon an object which results from its interaction with another object. Forces result from interactions! As discussed in Lesson 2, some forces result from contact interactions (normal, frictional, tensional, and applied forces are examples of contact forces) and other forces are the result of action-at-a-distance interactions (gravitational, electrical, and magnetic forces). According to Newton, whenever objects A and B interact with each other, they exert forces upon each other. When you sit in your chair, your body exerts a downward force on the chair and the chair exerts an upward force on your body. There are two forces resulting from this interaction - a force on the chair and a force on your body. These two forces are called action and reaction forces and are the subject of Newton's third law of motion. Formally stated, Newton's third law is:
For every action, there is an equal and opposite reaction.
The statement means that in every interaction, there is a pair of forces acting on the two interacting objects. The size of the forces on the first object equals the size of the force on the second object. The direction of the force on the first object is opposite to the direction of the force on the second object. Forces always come in pairs - equal and opposite action-reaction force pairs.
A variety of action-reaction force pairs are evident in nature. Consider the propulsion of a fish through the water. A fish uses its fins to push water backwards. But a push on the water will only serve to accelerate the water. Since forces result from mutual interactions, the water must also be pushing the fish forwards, propelling the fish through the water. The size of the force on the water equals the size of the force on the fish; the direction of the force on the water (backwards) is opposite the direction of the force on the fish (forwards). For every action, there is an equal (in size) and opposite (in direction) reaction force. Action-reaction force pairs make it possible for fish to swim.
Consider the flying motion of birds. A bird flies by use of its wings. The wings of a bird push air downwards. Since forces result from mutual interactions, the air must also be pushing the bird upwards. The size of the force on the air equals the size of the force on the bird; the direction of the force on the air (downwards) is opposite the direction of the force on the bird (upwards). For every action, there is an equal (in size) and opposite (in direction) reaction. Action-reaction force pairs make it possible for birds to fly.
Consider the motion of a car on the way to school. A car is equipped with wheels which spin backwards. As the wheels spin backwards, they grip the road and push the road backwards. Since forces result from mutual interactions, the road must also be pushing the wheels forward. The size of the force on the road equals the size of the force on the wheels (or car); the direction of the force on the road (backwards) is opposite the direction of the force on the wheels (forwards). For every action, there is an equal (in size) and opposite (in direction) reaction. Action-reaction force pairs make it possible for cars to move along a roadway surface.
Practice Questions from teh Newton's Laws Quiz
Why does a soccer ball stop moving after you kick it?
What has more inertia an elephant or a mouse? Why?
When you stand while riding a bus, why do you tend to fall backward when the bus starts moving forward?
Why is inertia important for you to understand?
Compared to its mass on Earth, the mass of 2kg rock on the moon is: a. the same b. more c. less
The force due to gravity acting on an object is called its mass. a. True b. False
Which of the following increases the inertial of an object? a. Acceleration b. Mass c. Volume d. Color
How can you increase the acceleration of an object?
If the acceleration due to gravity were to double to 19.6 m/s/s, what would happen to your weight?
A car accelerates at 55 m/s2 with a force of 55,000 Newtons. What is the mass of the car?
How much force is required to accelerate a 90 kilogram person at a rate of 12 m/s2?
There are 60,000 centimeters in ________________________ meters.
Write 265,000,000 in scientific notation.
Write 0.0054 in scientific notation.
STUDY NOTES FOR POTENTIAL/KINETIC ENERGY, MOTION OF A PENDULUM, AND FRICTION.
QUIZ ON WEDNESDAY, SEPTEMBER 19th.
BE READY.
Potential Energy is the energy of position. A rock on the edge of a cliff, or a skier on top of a steep downhill run , or a pendulum with 500 grams of mass all have gravitational potential energy.
Kinetic Energy is the energy of motion. ANYTHING that moves has kinetic energy.
When Potential Energy is at 100%, Kinetic energy is at 0%. As the mass of the pendulum changes from Potential Energy to Kinetic Energy, PE (potential energy) decreases as KE (kinetic energy) increases.
Many forces act against PE/KE . A force that opposes motion is called FRICTION a n include air resistance, surface area, incline or position, mass, etc. Friction is a HUGE variable.
There are 4 types of friction. Sliding Friction (like pushing the table across the linoleum floor)
Rolling Friction (Like your skateboard or car)
Fluid Friction (like swimming in water or using lubricants)
Static Friction (Static means no motion)
Generally speaking, the rougher the surface the greater the friction.
Friction can be reduced by adding lubricant or increasing the force upon the object (like giving it a push or raising the incline, etc.)
Remember the Pendulum Lab. You must be able to track the motion of a pendulum on a qualitative graph. Be able to show me where:
Potential Energy is at 100% and 0%
Kinetic Energy is at 100% and 0%
Show where the pendulum is going the fastest and slowest
Where the speed is increasing energy.
Where the speed is decreasing energy.
The Law of Energy Conservation state that “Energy cannot be created or destroyed, it can only change forms”
The Scientific Method always starts with a question or problem, then form a hypothesis, design an experiment to test your hypothesis, collect data, analyze the data, make a conclusion and report your finding.
Two types of data may be collected and analyzed: Qualitative Data (how something looks, feels, responds, etc.) and Quantitative Data ( how fast, how far, uses numbers to calculate)
Study Notes for Learning Styles and Multiple Intelligence
There are three ways humans "input" information: visually, auditorialy, and kinesthetically (eyes, ears, hands)
Everybody has a personal 'preference' of learning style, something that comes naturally. Developmentally, kinesthetic learning is the primary way for children to learn (think of your little brother or sister touching and trying to put everything in the house in their mouth!) Most eighth graders are strong kinesthetic learners.
Dr. Howard Gardner developed the "Multiple Intelligences" based on the three learning styles. While we all have an 'intelligence' that comes naturally, we can learn how to use other methods.
There are 8 accepted Multiple Intelligences (9 when counting the 'naturalist'). If a person understands how they personally learn 'best', they may be able to learn more faster by practicing using their natural intelligence while learning how to use the other intelligences to enhance understanding.
If you have not taken a Multiple Intelligence test yet, go to my LINKS page and find one that appeals to you. Compare the results with the test we took in class.
Quiz on Friday September 7....
Upcoming unit will be about Density. Use the following Pre Quiz to find out what you need to know!
1.Find the density of ice when the volume is 108.7ml and the mass is 100g.
3.Suppose a student finds that 23.50 mL of a certain liquid weighs 35.062 g. What is the density of this liquid?
4.At a local pawn shop a student finds a medallion that the shop owner insists is pure platinum. However, the student suspects that the medallion may actually be silver and thus much less valuable. The student buys the medallion only after the shop owner agrees to refund the price if the medallion is returned within two days. The student, a chemistry major, then takes the medallion to her lab and measures its density as follows. She first weighs the medallion and finds its mass to be 55.64 g. She then places some water in a graduated cylinder and reads the volume as 75.2 mL. Next she drops the medallion into the cylinder and reads the new volume as 77.8 mL. Is the medallion platinum (density = 21.4 g/cm3) or silver (density=10.5 g/cm3)?
5.A student wants to identify the main component in a commercial liquid cleaner. He finds that 35.8 mL of the cleaner weighs 28.1 g. of the following possibilitries, which is the main component of the cleaner?
6. Mercury has a density of 13.6 g/mL. What volume of mercury must be taken to obtain 225 g of the metal?
7. Francesca was in her basement and found a coin that looked very old. She wanted to find out if this treasure was worth anything. She was able to weigh the coin and find out that it weighed 3 g and the volume was .33 g/cm3. How would this help her discover the value of her coin?
8. What is the value of her coin? I have a chart of metal densities at the front of the room.
9. Will Francesca’s coin float in mercury? Come to the front of the room to see the results of your finding.
10. Using the two rulers provided carefully measure and find the density of one of your science books (or any book handy if you're on the road!)
Mixtures, Compounds, Solutions.
In the bowl, mix an equal quantity of the Elmer's glue and water (about 2 Tablespoons each). Mix well with a spoon, stick, or finger. Observe closely and answer these questions;
Now, in the jar or graduated cylinder, we'll make a saturated solution of borax. Combine a tablespoon of borax powder with 300mL of water and stir. If all of the borax powder dissolves, then you need to add a bit more. When you get to the point where no more borax will dissolve, then the solution is saturated. We have just used H2O to make a compound solution. H2O is a compound. What are the pure elements that make the compound H2O?
Can something be called a solution if particles can still be seen in the liquid? ______________
Now, add about two tablespoons of the borax solution to the bowl with the glue and water mixture and stir quickly. Use your hands and work the ‘stuff’ How does it feel? If you had just invented this, what would you call it? ____________
The resulting mixture should be slimy or gooey. You can save your goop for a long time by putting the 'stuff' into a sealable plastic bag. DO NOT TAKE IT TO YOUR OTHER CLASSES! If your goop dries out, you can add a bit of water back into it. If it gets too dry, you'll have to start over.
Now read the following and answer the rest of the questions.
When you mix Elmer's glue with a bit of water, you make a substance that is known as a polymer (polyvinyl acetate) and that the borax solution (sodium tetraborate) is a 'cross-linking' substance that binds the polymer chains together to make the glue solution thicker. So, as the polymer chains get more 'bound-together', it gets harder for them to move around, and your goop starts to be more like Silly-putty™. Experiment with adding more borax solution to see if this indeed makes the slime thicker or thinner.
Knowing just how much Borax solution to add is the trick to this experiment. If you add too little, your slime will contain excess glue (the polymer part) and it will be sticky. If you add too much, your slime will be very wet (too much 'cross-linking'). Touch your slime with your hands when it doesn't look like a liquid anymore. If your slime feels sticky, try adding a little Borax solution. If your slime feels very wet and slippery (but is not still runny), remove it from the container and kneed it in your hands. In a few minutes, any extra Borax solution will evaporate or be absorbed.
You might get some of the Elmer's glue on your clothes. If you do, just get some clean water and wet the area well to help remove the glue. The goop that we made isn't really toxic, but I wouldn't eat it. Borax is used to clean clothes (it's a form of soap), so that won't be much of a bother. If you use food coloring, it'll stain your hands (for a while) and your clothes, so be careful.
A tablespoon of borax has a mass of 50 g. We used 300 mL of water to make our solution. What is the concentrate of the borax solution? _____________
Is the goop you made a liquid? A solid? Does it bounce? Break? Stretch? What type of matter would you call it? ________________________________________
If you could put goop on the Periodic Table, what category would it be? ___________________
Now clean your station and put this completed lab sheet in the IN box. You may take your goop with you in the plastic baggie but DO NOT make it a problem in other classes. Science ‘stuff’ stays in science class!
There is a physics/chemistry quiz on Wednesday, March 14. Use your Chapter 3 "Elements, Comounds, and Mixtures" review worksheet as a study guide. If you have your "Introduction to Matter" text book, go over Chapter 3 and do the REVIEW questions at the end of the chapter to prepare.
