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Sistema óseo – Test, Anatomía educaplus.org

Sistema óseo – Test, Anatomía educaplus.org

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Scitable | Learn Science at Nature


A free science library and personal learning tool brought to you by Nature Publishing Group, the world’s leading publisher of science.

Scitable currently concentrates ongenetics, the study of evolution, variation, and the rich complexity of living organisms. As you cultivate your understanding of modern genetics on Scitable, you will explore not only what we know about genetics and the ways it impacts our society, but also the data and evidence that supports our knowledge.

Scitable | Learn Science at Nature

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RUBBER FLUBBER

Receta de Flubber

  • 2 cucharadas de agua
  • 2 cucharadas de plasticola blanca o transparente
  • 2 cucharadas de solución de borax
  • colorante de alimentos

Solución de borax: mezclar en 16 cucharadas de agua caliente 1/4 de cucharada de borax y mezclar.

Table of Contents

Experiment

  • Summary
  • Investigative Question
  • Hypothesis
  • Procedures
  • List of Materials
  • Observation
  • Science terms
  • Science behind the experiment
  • Resources

Conclusions

  • Answer to Investigative Questions
  • Hypothesis comparison
  • Final reflection

The Experiment

Summary: Our experiment was to mix a monomer of glue and water and a catalyst of borax and water to create a polymer.

Investigative Question: What is a polymer?

Hypothesis: We think a polymer is slimy and sticky like a thick gel.

List of Materials:

2 teaspoons Elmer’s glue

¼ teaspoon 20 Mule Team Borax
4 teaspoons very warm water divided

2 small plastic cups
Stir stick

Procedures:

  1. Measure 2 teaspoons of water in another small plastic cup.  Add 2 teaspoons of Elmer’s glue.  Stir until monomer is mixed.
  2. Measure 2 teaspoons of water in small plastic cup.  Add ¼ teaspoon of borax and stir until catalyst is dissolved
  3. Slowly mix the catalyst into the monomer.
  4. When the polymer becomes too stiff to stir, knead with hands.
  5. Examine and observe the polymer
Observations:
  • We added the borax to hot water, it took 1 minute of stirring to get all the borax to dissolve.
  • Next we added glue to hot water in another cup, this took ½ minute to mix.
  • We added the borax solution to the glue solution and when we started stirring it became thick and sticky within ½ minute.
  • The flubber separated from some of the water in the cup.
  • We removed the flubber from the cup and kneaded it until most of the liquid was mixed in.
  • There is very little smell (slight white glue, bleach smell)
  • It is white and shiny lump
  • The texture is smooth and rubbery feeling
  • The flubber could flow downward when held, but would break if pulled or stretched.
  • It could be rolled into a ball, but would not keep its shape.
  • The flubber could be broken into smaller pieces and then be molded back together with no evidence of seams.
  • It bounces, but it since it is not round (or a symmetrical shape, it moves at an unpredictable angle from the surface.
  • The flubber eventually dries to a firm rubbery texture.

Borax and Water

The Catalyst – Borax & Water

The Monomer- Glue & water Mixing the catalyst into the monomer

Mixing them together

The flubber!

Marker on flubber

See the flubber stretch!

table of contents

Research

Science Terms & Concepts

Borax – A hydrated sodium borate, Na2B4O7·10H2O, an ore of boron that is used as a cleaning compound.

Catalyst – A substance, usually used in small amounts relative to the reactants, that modifies and increases the rate of a reaction without being consumed in the process.

Compound – A substance made of more than one element

Elastic – capable of resuming former size and shape after being stretched

Molecule – the smallest bit of a substance that still ahs all the properties of the substance.  Molecules have one or more atoms.

Monomer – A molecule that can combine with others to form a polymer

Polymer – compounds consisting of repeated linked molecules.  They tend to be dense, strong, and flexible.  Examples are plastic bottles, styrofoams, latex paints, and chewing gum.

Polyvinyl acetate – A vinyl resin, that it is available in the form of an emulsion that is readily diluted with water, is easily applied, and is safe to use because it contains no flammable solvents.

Science Behind the Experiment

Poly + Meros  = Polymer Polymers are composed of many individual units called monomers.  These monomers are linked together with chemical bonds to form long chains.  The word polymer comes from the Greek words poly: “many” and meros: “parts”.    Polymers are composed of many individual units called monomers.  These monomers are linked together with chemical bonds to form long chains.  A typical polymer is made of 1,000 to 10,000 monomers linked together.

White glue is a water-soluble polymer.    Borax is a cross-linker.

Elmer’s glue has a chemical in it called polyvinyl acetate.  This is a very long and flexible molecule.  Borax solution has a chemical in it called boron. When the borax solution is added to the glue solution, the boron atoms help link the long polyvinyl acetate molecules to each other so they cannot move and flow as easily. When enough polyvinyl acetate molecules get hooked together in the right way, the glue solution changes from being very liquidy to a rubbery kind of stuff!

Principles:
  • Polymers are stretchable, pliable, and flexible (not brittle, hard, or rigid)
  • When cross-links are formed in a polymer, its chains of molecules are connected in several places, production a stronger and more elastic polymer
  • The elasticity of some polymers is affected by temperature.
Facts:
  • Some polymers occur naturally, as in the juice of rubber or aloe plants, and some are manmade.
  • Polymers tend to be dense, strong, and flexible. Examples are plastic bottles, styrofoams, latex paints, and chewing gum.

Single Chain Polymer
The chain is really flexible!
Cross-linked Polymer
The group is not as free to move around!

Resources

Playing with Polymers – http://www.eecs.umich.edu/~coalitn/sciedoutreach/funexperiments/agesubject/lessons/polymer.html,
University of Michigan, June 2000

Flubber, A Lesson In Polymer Chemistry –
http://www.knownet.net/users/Ackley/flubber.html, The Teacher’s Desk, Dec. 21, 1997

Fabulous Flubber!
http://chemistry.org/portal/Chemistry?PID=wondernetdisplay.html&DOC=wondernet\activities\art\flubber.html, Wondernet, American Chemical Society, December 13, 2001

Table of contents

Conclusion



Answer to Investigative Question:

What is a polymer?  A polymer is a chemical compound that is stretchy, flexible and elastic.  It is created is unique because it has qualities of both a solid and a liquid. It can take the shape of its containers like a liquid does, yet you can hold it in your hand and pick it up like a solid. Polymer molecules chain themselves together (they can stretch and bend like chains) and that makes them special. Jell-O, rubber bands, plastic soda bottles, sneaker soles, even gum are all forms of polymers.

Hypothesis comparison:

We thought a polymer would be slimy and sticky like a thick gel and found that it was moist but rubbery, and strong but flexible.

Final Reflections:

We think this was a very interesting experiment to perform.  Everyone enjoyed playing with the flubber and noticed that it got a lot of attention from everyone in the school. We made a lot of batches of flubber during the day and once people started playing with it it was hard to stop.The elastic quality of the flubber was probably the best part. The flubber could be allowed to stretch slowly until it was like spaghetti and then formed back into a soft ball. It had the properties of a thick liquid when it spread, but still maintained its shape when moved. W feel that we gained some knowledge about why polymers are commonly used because of their strength and flexibility.

RUBBER FLUBBER

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¿Cómo hacer Flubber | How To Do Things.com

¿Cómo hacer Flubber

Step 1:

El material que se requiere.

  • A 4 oz botella de pegamento Elmer’s-Todos
  • Alimentos para colorear
  • 1 cucharadita de 20 de MULE Equipo de Bórax
  • Agua caliente
  • 2 tazones de mezcla
  • Cuchara de madera o espátula
  • Cartel de pintura, brillo (opcional)
Step 2:

Preparar la cola. Vierta el contenido de la botella de pegamento en un recipiente vacío; enjuagar el frasco con agua tibia para limpiar la cola de la botella. Añadir diez gotas de colorante de alimentos – de color verde o de cualquier otro color que te gusta y mezclar la cola para colorear y así utilizar la cuchara de madera. Opcionalmente, puede utilizar pinturas cartel en el lugar de los alimentos para colorear, pero recuerde que la pintura puede ser tóxico. Añadir dar brillo a la flubber interesante textura.

Step 3:

Preparar el bórax. En otro tazón, añadir una cucharadita de 20 de MULE Equipo de bórax y disolver en una taza de agua tibia. Revuelva cuidadosamente hasta que el polvo no deje residuos.

Step 4:

Mezcle el pegamento y soluciones de bórax. Revolviendo continuamente con la cuchara de madera, la cola para la mezcla en el recipiente que contiene la mezcla de bórax. Una vez que ambos ingredientes son mezclados adecuadamente, que se convertirá en un espeso globalización. La globalización amasar hasta que sea suave y seco. El flubber ya está listo. Si desea flubber espesa, agregar más bórax, disminuir la cantidad de bórax si usted lo desea slimier y más fluido.cs naturales

¿Cómo hacer Flubber | How To Do Things.com

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Construyendo átomos | Microsiervos (Ciencia)


Build an Atom es una preciosa forma de visualizar cómo son los átomos y cómo van creciendo y organizándose los electrones en las órbitas según se van haciendo más y más complejos.

Construyendo átomos | Microsiervos (Ciencia)

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