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24.01.2017


Case-lesson “Secrets of water”
Case-lesson “Secrets of water”

Category: Science, nature and man

Level (grade): 8 - 11

Subject: Natural phenomena

Objective: Find out what properties of water make it an abnormal substance in terms of physics and chemistry but absolutely indispensable in terms of biology and health.

What information is waiting for me here?

  • What are the properties and characteristics of water of a living organism?
  • Why water is considered an abnormal substance?
  • What fundamental and practical knowledge will I need?
  • Is it possible to paint on water and create sculptures of it?
  • Why is water beneficial not only for the human body but also for psyche?
6 scans of the subjects, phenomena and practices:
Introduction

While we are not thirsty, we do not even think about the importance of water in our life. The human body is largely composed of water, but we rarely perceive the aquatic environment as “ours”. So what is the difference between the water of the body, the water in a glass, in a rain drop, in a river? Which water is “right” for us? Why do some scientists call water an abnormal substance? Let’s try to reach the heart of the matter.

 

Physics

Ordinary water still supplies scientists with complicated issues to solve.

Which water freezes faster: hot or cold?

The obvious answer – cold – is incorrect!

Erastus Mpemba has noticed that, in fact, hot water freezes faster than cold water when two water masses are exposed to the same conditions with temperature below zero. And no one knows why. The only assumption is that Mpemba effect appears as a result of the heat circulation process called convection. In the container hot water rises, displacing cold water and creating a “heated top”. Scientists assume that convection can somehow speed up the cooling process, allowing hotter water to freeze faster than cooler, despite the distance on a mercury column that it needs to overcome on the way to the freezing point.

 

Half a century of research hasn’t given an answer yet regarding why people can fall on ice. Scientists are unanimous in the suggestion that a thin layer of liquid water on the surface of solid ice causes slipping, and fluid mobility makes it difficult to move, even if the ice is thin. But there is no clear answer as to why ice, unlike most solids, has this layer. Some believe that the process of sliding itself makes the surface meld. Others believe that the liquid layer exists before the appearance of a sliding object, and that it is formed through the internal motion of the surface molecules. How does water boil in space? On Earth, boiling water creates thousands of tiny bubbles of steam. But in space a giant oscillating bubble is created. In 1992 an experiment aboard the spacecraft was conducted. After that physicists decided that a simplified type of boiling in space is obviously associated with the lack of convection and lifting force as far as both of these phenomena are created by gravity. On Earth, these effects cause seething that we see in a kettle:

Why are some items able to keep afloat, although they are clearly heavier than it and should sink? The reason is the force of surface tension – the property which makes the outer layer of water mass (and some other liquids) behave like flexible shell. Surface tension appears due to the fact that water molecules are weakly bonded with each other. Thus surface molecules undergo internal efforts of molecules under them. Water will remain intact until the force that breaks it exceeds the force of these weak bonds and breaks through the surface:

 

For example, the photo above demonstrates a paperclip on the surface of water. Although metal is denser than water and therefore must drown, surface tension doesn’t allow the paperclip to break the surface.

Why is snow capable of boiling in seconds? When there is a huge difference in water and air temperatures an impressive effect occurs: if you splash a pan of boiling water (100°С) into the air with the temperature of -34°С, the boiling water will instantly turn into snow:

The explanation is the following: extremely cold air is very dense; the distance between its molecules is so small that there is not enough space for the transfer of water vapor. At the same time, boiling water actively produces steam. When it is thrown into the air, it breaks up into droplets, which is why even more room for spreading of the steam is created. This is a problem. More steam than the air can hold is released and, therefore, it spreads, embodies itself in microscopic particles in the air, like soda or calcium, and forms crystals. This is just how snowflakes are formed.

In addition, water can exhibit “anomalous” properties, since many physical and chemical parameters of water fall out the general laws for substances of its type (water row):

 

Pure water without additives has become a benchmark, a reference point for scales of color, turbidity, scent and transparency:

 

Chroma scale of natural water

Pure water lacks taste. Its taste if formed of impurities and solutes.

Water has a triple point – a condition under which all three phases (liquid water, steam and ice) can exist simultaneously. Conditions for this are the temperature of 273.16 K and the pressure of 610 Pa.

Some scientists follow the cluster theory to explain the anomalous properties of water. It states the next: because the water molecule is a polar one, the individual molecules can organize themselves into clusters (ordered structure of several molecules of the same substance). Clusters, in their turn, provide a pseudo-crystalline structure, which explains the abnormal for liquid properties.

 

Cluster theory is the basis of the explanation of the phenomenon of water memory. But these studies are “at the peak” of science, and they are largely discussable.

Question:


Have you ever encountered water in all three conditions simultaneously (triple point of water)?

Chemistry

What kinds of water are there? The answer “soft and hard” is sometimes surprising. But these are the conventional names of water that contains impurities of a definite composition.

Hardness of water depends on the content of alkaline earth metal salts (mainly calcium and magnesium) in it. Have you noticed that sometimes you wash your hands for longer than usual but they still seem soapy? And sometimes you wash them quickly but feel that they are clean already:

 

Water enters into virtually all types of chemical reactions. It can act as a reagent and even as a catalyst. Some chemical reactions can occur only in the presence of “water traces”, i.e. start with very small quantities of this extraordinary substance.

Let’s examine successively these basic types of reactions in which water can participate:

1. Interaction with metals. This is a fairly tempestuous type of reactions that occurs with the release of hydrogen:

 

An example of the reaction of sodium with water:

2. Interaction with nonmetals. Since these are the substances with less activity, heating is necessary for occurrence of reactions. For instance, the reaction with formation of carbon monoxide:

 

3. Interaction with oxides of metals and nonmetals. It should be noted that these are reactions of bonding, not redox reactions. For example, the reaction with the formation of sulfuric acid:

 

Those oxides that don’t react with water have become the basis for waterproof paints: chromium oxide, zinc oxide.

4. Interaction with electricity. During this reaction water breaks down into hydrogen and oxygen; an internal redox reaction occurs (oxidation and reduction processes occur only because of the hydrogen ions and oxygen of water):

 

5. The formation of hydrates and crystalline hydrates:

 

6. Another important type of interaction is biosynthesis with formation of oxygen:

 

This reaction is an element of photosynthesis.

There are also reversible reactions when certain substances interact, and one of the products of the reaction is water. For example, the interaction of chalk (calcium carbonate) and hydrochloric acid:

 

In the reaction between alkali metal hydroxides and strong acids one of the products will also be water:

 

Biology
What is the amount of water in the human body? This childish question has quite adult and science intensive answer. Body fluids differ in water content, as well as intracellular and intercellular fluid do. What are these indicators?

 

60% of weight of an adult, weighing 70 kg, is a liquid. This is about 42 liters, 28 of which is intracellular fluid. All living organisms have the identical composition of this fluid. It is necessary for execution of the basic life processes:

• transformation, storage and usage of energy;

• homeostasis (the relative independence of the internal environment from the external environment);

• replication (the process of reproduction (synthesis) of deoxyribonucleic acid (DNA). Thus from one DNA molecule, as a result of its doubling, two new molecules, which are the exact copies of the original DNA, are formed);

• performance of specific functions by living structures.

Intracellular fluid consists of water with dissolved ions and small molecules: salts, sugars, amino acids, fatty acids, nucleotides, vitamins and gases.

Extracellular fluid is represented by intercellular fluid and plasma. There are 14 liters of this fluid (for 70 kg of body weight).

In a separate cell intracellular fluid is a soluble portion of the cytoplasm (cytosol), its “basic substance” that fills the space between cell organelles.

Cytosol is a part of the active environment for cell elements (structures). In the cytosol various metabolic reactions – the basis of all cell functions except for the synthesis of nucleic acids performed in the nucleus – occur. Various substances are reserved in the cytosol. For a living cell active cytosol streaming is typical. It is clearly visible on the movement of organelles. The fraction of water in the cytosol is almost 90%.

The ionic composition of intracellular fluid on average is quite different from the composition of extracellular fluid. The first contains much more potassium and magnesium ions, and the basic anion is phosphate. Concentration of glucose inside the cell is lower and concentration of protein is higher. There are membranes between the intracellular and extracellular fluids. Membranes are complex structures that carry out two-way exchange of substances and energy (information) between cells and the environment (extracellular fluid). According to tryphonov.ru/tryphonov2/terms2/intrac.htm the fluid composition is the following:

 

Therefore, it is important for humans not only to drink clean water, but drink water with the right balance of solutes, because we receive a part of necessary substances and elements specifically with water.

Health

Distilled water is unsavory or rather tasteless. Is it beneficial to drink water of this type of purification? At the first glance it seems that the answer is yes. But this is not completely true. People receive solutes through water and distilled water, in contrast, “washes” these substances out of the body. That’s why hygienists around the world insist on balanced composition of water additives, calling it physiological or biological usefulness of water. Often these requirements are the basis of national and international standards of drinking water quality.

People have long noticed that many diseases are associated with the lack of revenue and content of certain macro and micronutrients in the human body. Unlike vitamins which can be synthesized in the body, macro- and micronutrients come only from the outside. To ensure the body’s physiological needs of macro and micronutrients people must receive them in this proportion (out of 2.5 liters of water per day):

 

Example of a standard of physiological usefulness of water:

 

Question:


What kind of water you like the most: boiled water, bottled water, spring water or well water? What do you think, what kind of water is the safest? What kind is the healthiest for your organism? Present a few arguments.

Psychology/Relaxation

Everyone has their secrets of relaxation. Once armed with the most effective methods of relaxation, you can receive maximum benefit and satisfaction.

Psychologists often recommend turning on your imagination and imagining the sound of sea or waterfall in order to relax:

And the murmur of the water combined with birdsong:

Contemplation of water surface, glistening of water, shimmering colors of waves is also beneficial to our psyche, as well as the sound of quietly flowing water:

 

Perhaps this is a secret of aquariums and fountains popularity. A fountain or an aquarium can become a small home decoration. And they can also transform into a show that will attract thousands of exited tourists.

The combination of light, color, music and audio streams is able to both relax and inspire people.

For example, fountains show in Dubai:

Hence, we should learn to use the beauty of the world, the beauty of water for relaxation and finding harmony.

Art

Water is not only the basis for paints or an object for portraying. It can inspire a painter, photographer, sculptor, and, at the same time, become an instrument or canvas itself.

Water instead of canvas is the foundation of a modern painting direction called Ebru. In the beginning, this kind of art has just been a form of processing of paper, called “Turkish marbling”. Gradually it has gained popularity, taken the shape of an independent genre and even given impetus to the development of spectacular Ebru shows. Here are some examples of Ebru art:

 

Here’s how such works of art are created:

Water as a substitute for marble and sculptor’s cutter.

For instance, one sculptor – Markus Reugels – creates fragile and bizarre water sculptures:

 

 

Water is a model for a photographer.

Photographer Jack Long has become the author of a series of photos called “River”. He has used the water of a river near which he’s resided:

 

Also, using multiple cameras, he has created a series of 3D-images of water called “Gallery”. He has managed to capture the play of colored streams of small fountains, water movement, and to lock them into static photographs. Here are these “water sculptures”, caught and retained with the photographer’s talent:

 

Question:


Have you ever encountered any of the aforementioned kinds of art?

Accelerated and interactive methods
1. “The art of Ebru” (Case-lesson “Secrets of water”)

The essence of the game: It can be conducted both as a team game and an individual task. The game will require: liquid (thick starch solution mixed with office glue), acrylic paints, diluted with water, trays with low sides, paper, napkins, sticks and brushes.

Then children dribble droplets on the surface of the liquid, creating a pattern, background or some separate elements. The liquid, droplets, their transformation and imagination of kids themselves will inspire children.

After that a sheet of paper that fits the size of the tray is placed onto the surface and left alone for a few minutes. When the edges of the sheet begin to curl, you can carefully lift it and put on a clean horizontal surface to dry completely.

OBJECTIVE: To revitalize, mobilize children, “turn on” good mood and positive thinking.
Lesson’s summary:

   

1

The results of the case-lesson can be complemented with findings of students

 

2

What three websites have helped find important information

http://edufuture.biz/

https://ru.wikipedia.org/wiki/%D0%93%D0%B8%D0%B3%D0%B8%D0%B5%D0%BD%D0%B0 http://www.vodainfo.com/ru/about_water/types_water/hardsoft_water.html

3

To help student and couch:

http://edufuture.biz/

 

https://ru.wikipedia.org/wiki/%D0%92%D0%BE%D0%B4%D1%8F%D0%BD%D0%B0%D1%8F_%D0%BC%D0%B5%D0%BB%D1%8C%D0%BD%D0%B8%D1%86%D0%B0

 

http://vodamama.com/

 

https://ru.wikipedia.org/wiki/%D0%93%D0%B8%D0%B3%D0%B8%D0%B5%D0%BD%D0%B0 http://www.vodainfo.com/ru/about_water/types_water/hardsoft_water.html

 

4

Where can you get information for the case?

http://edufuture.biz/

 

http://meduniver.com/Medical/Physiology/684.html

 

http://www.tryphonov.ru/tryphonov2/terms2/intrac.htm

 

http://biolicey2vrn.ru/index/obmen_neorganicheskikh_veshhestv/0-392

 

http://www.argo-shop.com.ua/article-10025.html

 

5

           

Location of the lesson:

The case-lesson takes place in a classroom.

It is possible to conduct the lesson at a museum or library.

6

Contest:

Teams of boys and girls..

The score was:….

Tasks for them:

1. Which of the teams will name more substances – additives of the intracellular and extracellular fluids.

2. Write down the reactions of all types, presented in the “Chemistry” section.

The team that completes the tasks faster and more accurately wins.

7

Homework:

 Formulate five questions to the case-lesson (the individual task).

8

Duration:

90 minutes (double lesson)

9

Possibility to conduct the lesson with a student understudy: 

 

10

The acquired knowledge and developed competence:

Knowledge about peculiarities of freshwater distribution in the hydrosphere.

Knowledge about the history of development of water as a global resource and contemporary problems in this area.

Modern and prospective water architecture.

Practical skills in calculation of the movement on water with consideration of currents are acquired.

Gaining concrete geographical, historical, economical and other knowledge (given in the scans).

11

Tags:

Freshwater, lakes, rivers, underground waters, swamps, glaciers, water availability, stream speed, water intake, water clarification, plumbing, borehole, water wheel, well.

12

Authors:

 Hrabowska Larysa Leonidivna

13

Participated in the case upgrading:

 

 


The End

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