ENVIRONMENT

SUBSTANCES IN THE ENVIRONMENT

Introduction

Earth, our globe, is the living of all living creatures we know, including man, you for example.
Do not neglect your own house! Take care of a good maintenance; your existence depends on it.
We, men and women have the capacities and responsibilities to do so; we are no reasonless animals; we have got brains. Common sense too! And that sense should be based on knowledge, also knowledge about nature.
There is nothing in small stupid talk.

In this module you can collect some basic knowledge of the substances in our environment. We will treat only some substances in your environment and some of their properties, including substances that should not be there.
In another mudule we will talk about all kind of reactions that take place in our environment.

It is nice to include the old Greek division of substances on earth. They thought that all substances were composed of four elements: earth (solid), water (liquid), air (gas) and fire (spirit).
Enything solid, hard, contains lots of 'earth'.
Anything liquid must contain lots of water.
anything gaseous / thinny must contain air.
And yes, if you set fire to one or another substance, fire comes out! You can notice that. So fuel must contain lots of fire.
Funny yes, but modern science has complete different ideas.

Content

5. Cleaning substances

6. Saving energy

6.1 White roofs

1. EARTH

Geography gives answers to the question: from where come earth and earth layers? How did they occur? What are vulcanos? Why is there erosion? Where to oil and gas come from, and what is chalk?

1.1 The composition of the earth crust

Our earth is mainly composed of two components:

Organic material (humus with all kinds of nutrients)
Inorganic material; the various kinds of stone (like sand; they contain minerals)

The pH-value can vary: stone of the type of 'granite' has a bit lower pH, is a bit more acid, while Calcium carbonate layers are more basic, so with a bit higher pH value.

The upper layer of earth where we find rivers, seas and oceans, mountains and living creatures, has the following composition:

ELEMENTS	PERCENTAGES
Oxygen	47
Silicium	28
Aluminium	8
Iron	5
Calcium	3,5
Sodium	3
Potassium	2,5
Magnesium	2
Other elements	1

The very dominating presence of Oxygen and Silicium in eart layers is due to the sand that is highly built up of SiO₂ and its derivates.

Question 1
What kind of ground could be below your house?

1.2 (Artificial) Fertilizer

The ground on which we live serves for walking, building houses, but in particular: to grow food in agriculture.

Normally, plants can find all needed substances and minerals out of the ground on which they are growing, but agriculture of farmers is using so many substances, that the ground gets exhausted, has no longer all needed stuff for plants.
So we fertilize the earth with extra substances. We use natural fertilizer (manure), but also artificial manure, like Potassium phosphate, ammonium nitrate, ureum, minerals with Potassium-, Magnesium-, Sodium- and Copper or Iron-ions.

Nitrate is important and contains the element Nitrogen. 80% of the air is Nitrogen, so you would suggest: Nitrogen in abundance. But a problem is that this is Nitrogen in the air (N₂) that not easy transfers to Nitrate.
Some plants are capable to change (N₂) into nitrates.

Plants receive most Nitrogen from (artificial) manure, like added ureum and nitrates.

In nature we have a so called Nitrogen cycle:

Artificial fertilizer of course does not only provide nitrates.
The choice of fertilizer depends also on the desired pH in the ground.

Question 2
Nitrogen in the air reacts difficultly with any other element or with any other compound. That's why Nitrogen sometimes is called an 'inert' substance.
It is special that certain plants can break the N₂-molecule to form nitrate.
Animal and men cannot do so.
Explain why it is difficult to break, to open the Nitrogen molecules.

2. WATER

The biggest part of water on earth is salty water, in the oceans and seas. They occupy the biggest part of our planet.
The water molecule, H₂O, is a tiny, light and rather polar molecule, and it is an important dipole. The fact of being a dipole molecules corresponds with the fact that the two H atoms make an angle to the O atom. Both OH-bonds are polar covalent bonds with a large difference in Electronegativity (ΔE).
This dipole character is responsible for the important characteristics of water, like boiling point and melting point.

Sea water contains about 35 milligram solid per liter:

ELEMENT	AMOUNT mg/l
Chlorine	19,2
Sodium ions	10,7
Magnesium ions	1,3
Sulfite-, Potassium-, Calcium- ans Bromide-ions	±1,8
Other elements	±1,4
TOTAL:	±35 mg/liter

2.1 The water cycle

Salts do not evaporate. So, rain water, even if that comes from the (salty) oceans, does not take salt with it; it is 'sweet' water and therefore suitable as drinking water for men, animal, plant.
But during the process of flowing back, via rivers, to the sea, that water absorbs small amounts af different salts and that's how the sea collects every time more salt.
Lots of rain water does not enter the rivers at all, but remains in the bottom of the earth. There people find most drinking water today.
This is normal; it goes that way for millions of years.
But something becomes disturbingly when rivers do not longer transport natural salts to the sea, but also polluting salts, mostly caused by fertilizers and insecticides. Nitrates, ammonium salts, etc are very well soluble in water, and difficult to filter out. If that comes into the rivers, it is transported to the oceans.
Even worse when it enters the sweeet water stock for drinking water.
Apart from artificial manure, there are many other sources of water pollurion: industrial waist, wrong substances that through the air enters the water, like Sulphur dioxyde, etc.
To clean all this, we have different methods, for example the precipitation, filtration, treatment with Chlorine, etc.

Question 3
Certain agricultural fiels recieve so much of fertilizer that there is a problem with the drinking water.
What could be that problem?

Question 4
The ground under a garage can contain lots of mineral oil + its derivates.
What could be the danger of this situation?

Question 5
What is the most important property of the water molecule, responsible for being liquid at normal temperatures (knowing that water molecules are as light as natural gas molecules.)?

Goto answer 06-05

3.1 The composition of air

The normal composition of dry and clean air in percentages (so without counting with humidity and pollution):

SUBSTANCE	PERCENTAGE
Nitrogen	78
Oxygen	21
Argon	1
Carbon dioxyde	0,04 (!)
other noble gases	0,003

You know that the air may contain a certain percentage of water vapor (humidity).
The humidity can vary from extremely dry (0%) to very humid (100%)

Question 6
The components of air - in general - are non polar substances.
Is that by accident, or could this have a reason?

Question 7
It is possible to separate the air components in a process of fractionated distillation.
But that is only possible with liquid air, and you must do that at very low temperatures.
Explain that process.

Ozon and Carbon dioxyde belong in the atmosphere. Carbon dioxyde is not poisonous, but may not increase to much (what unfortunatele happes the last hundred years). It is risky.
Ozon is located very high in the atmosphere (fortunately, because ozon is poisonous for living creatures). The Ozon above has an important function: it absorbs (holds) the ultra violet radiation from the sun.

Substances that do not belong to normal air, mostly are air polluters like (fine) dust, Carbon monoxyde, Sulphur dioxyde, the various Nitrogen oxydes, mostly coming from combustion processes.

Question 8
Describe a physical method to purify the air.

The last hundred year the amount of CO₂ in the air has increased to 0.04%. It never was that high since humans are on earth.
If CO₂-production continues, lot of sun heat will be absorbed on earth in stead of being reflected to space.
The earth can get hotter, the oceans fuller, climate changes.

Question 9
Which phenomena can be expected with climate change?

4. Fire

In the ancient times the Greek (phylosopher Aristotle) developed a theory that all matter should be built up of (four) elements; being:
earth, water, air and fire.
Att.: Those days they had a different concept of 'element' than we have in our modern society. But nevertheless, they found that matter is constitued of four elements.
Well burning matter, like wood, must contain lots of the element fire; isn't that what comes out when burning wood?!
Solids must contain lots of the element 'earth'. Liquids contain the water element.
If any matter start to bubble, that matter contained the element 'air'. etcetera.
It was the scientific way of thinking in those days.

Question 10
Do you know what fire is?
Is it a substance? Explain your answer.

Nowadays we know that fire is a form of heat energy that appears during exothermic chemical process; while that heat appears at one concentrated spot. Fire is a kind of high concentrated heat energy.
It is not really matter, although you may need particles to see the fire. In most cases, small particles are present in the hot spot; they start to glow and that causes the yellow color, sometime blueish. Also other colors can be observed.

The atoms of some substances involved in this high energy (substances that can be put into that fire) can - if not burned themselves - become 'excitated': electrons of those atoms receive temporarily some extra energy, and immediately donate again this extra energy. That outcoming energy often is radiation in the form of visual light, like blue, green, violet, yellow, etc. dependent on the character of the present atoms. (see module 1)

In the nineteenths century, European science knew a special theory about fire. They introduces a new concept: "phlogiston".

Phlogiston should be a volatile substance that escapes from a burning substance (a bit Greek thinking)

Below a chemical reaction that really takes place according to modern chemistry. It turns out that nothing comes out op a burning substance. on the contrary!
Later more about this.

This phlogiston theory was rejected, because nor with deduction nor with practical research the existance of phlogiston could be proven. Also they were able to measure that at burning an element, the product became heavier in stead of lighter. So what: something comes out?

Question 11
In those experiments they determinated the mass of substances before and after burning.
Observations do absolutely not confirm the existance of something like phlogiston.
Try to give that rational in your own words.
Goto answer 06-11

5. Detergents / cleaning materials

Cleaning means mostly: remove certain substances from where they should not be.
We clean dishes, we brush our teeths, we wash our hair, we clean the windows, etcetera.

How is that: removing dirt, unwanted substances?

Therefore we have lots of methods, but three are important categories:

The physical way
Weap and sand, like brushing teeths. Tooth-paste contains an amount of Calcium carbonate, a solid tiny divided substance that helps you to remove tooth absorbed substances. Brushing means simple: the tiny particles sand the dirt away, like you clean a pan. Nowadays very tiny plastic grains are used that are polluting drinking and other water.
Trouble water can be filtrated; also very physical.
Another physical way is the use of certain solvents: aceton is an example. It is used as nail polish remover. Nail polish dissolves in aceton. Such a process is sometimes consedered as a chemical process.
The chemical way
Chemical reactions are applied to clean matter. The chemical reaction will be treated in the following modules, but here already an example:
Cooking pans regularly used to boil water (it happens also in washing machines and kettles) show after some time a thin layer of Calcium carbonate (Calcite).
It is not easy to remove physically; sanding will damage the pan of kettle or the heating element.
In this case you can use a (not too strong) acid, like vinegar, that reacts with Calcite. the product is Calcium acetate that dissolves in water. So rinsing at the end takes the product and the dirty layer has gone.
Another example:
Chlorine can be used to clean water. The chlorine is an oxydator that reacts with some dirt that can be oxydated, like bacteria.
The physical-chemical way
The use of solvents is in fact not completely chemical, nor completely physical, but kind of mix: physical-chemical.
The use of soap is a mix of chemical and physical cleaning. In a way, soap reacts with the dirt, but is also 'sands'.

Question 12

Aceton is a non polar liquid that removes nail polish.
Normal nails contain a certain amount of natural fat.
What problem could have someone that ofter uses that remover?
Imagine and describe a method to remove dirt stains from cloths.
What to do if you have god Iodine stains on your skin?
your hands stick with wetty sugar. Do you need soap to remove that?
Some people have a bad smell in their mouth; how to prevent that?

Saving energy

White roofs

under construction