The third unit of natural water
subject 1
a composition of water. The physical properties of hydrogen:
hydrogen is a colorless, odorless,
soluble in water, density is < br> gas.
II. hydrogen chemical properties:
1. Hydrogen is flammable and can burn in air or oxygen, emitted blue flames.
chemical reaction equation:
use of the properties of hydrogen use:
2. hydrogen with reduction:
example: hydrogen reduction of copper oxide:
an indication of the reaction oxidants, reducing agents:
hydrogen reduction of iron oxide:
use of the properties of hydrogen use:
3. mixed with air or oxygen, hydrogen fire may encounter an explosion. the use of hydrogen, we should pay attention to safety, fire the former must
.
hydrogen test purity of the force method is: to collect a small test tube of hydrogen, with the thumb block the tube mouth, closer to the alcohol lamp flame, remove the ignition thumb. If you hear a sharp burst song to that of hydrogen impurities; If the sound is very small, compared to that of pure hydrogen.
III. hydrogen laboratory system of law:
1. Principle:
2. experimental device (drawing):
3. as you know, from the acid the replacement of the metal in the What are the characteristics of hydrogen:
IV. elemental and compound
1. simple substance is formed by the same elements of impurities. such as hydrogen (H2), oxygen (O2), nitrogen (N2), etc. .
2. compounds are formed by different elements of impurities. such as carbon dioxide (CO2), water (H2O), phosphorus pentoxide (P2O5), etc..
compared
elemental and compound concepts
For example
same point difference
elemental composition by the same elements of impurities of hydrogen (H2) oxygen (O2) of impurities the same elemental composition of different types of
compounds
pure material elements of water (H2O), carbon dioxide (CO2) elements of different kinds of impurities
3. one of quality and distinction between the most direct method of compounds from the composition of the distinction between elements only by a pure material is a single quality such as iron, aluminum, carbon, sulfur, etc.; by two or more elements of the pure material is a compound. or come from the name of the point of view, such as carbon dioxide, potassium permanganate. In addition, the single quality generally can not decomposition, while compound under certain conditions, may be decomposed into two or more substances.
subject 2
molecules and atoms
1. substance is invisible by the many tiny particles mm
,
,
composition.
2. molecular properties: molecular mass and volume are very small molecules are constantly in motion, the higher the temperature, molecular energy increases, the movement rate faster, have a certain interval between molecules.
same molecule of the same nature, different kinds of molecules of a different nature.
3. by the molecules of the material in the physical changes, the molecule itself
change, but the molecular The interval between changes, so that changed the state of matter.
by the molecules of the substance in a chemical change, the original molecular
material changes, other new elements generated.
4. molecule is
; molecule is formed by the
.
in a chemical change, change is
,
not changed.
no longer in a chemical change into smaller particles.
5. atom is the smallest particles of chemical change. metal, noble gas, diamond, silicon, etc. directly from the atomic composition.
6. atomistic point of view of molecular interpretation of pure mm materials and mixtures: molecular composition of the material by the
is pure quality, from
material is a mixture of molecules; and mixtures of various substances in the sub-sub-
chemical changes do not occur with each other.
water purification project 3
1. filter is separated from the liquid in the method of insoluble solids, the use of it can be water-insoluble solids and water left.
�� filtering you want to be
b. funnel below the filter surface by the edge of
three: a. the dumping of liquid, the beaker with a glass rod glass rod
b. contact with the end of the filter paper and funnel at the three exposure
c . funnel beaker bottom wall of the filtrate and undertake contacts
�� turbidity by filtering the filtrate is still possible reasons: �� damaged filter paper; �� filtrate was higher than the edge of the edge of the filter paper; �� equipment is not clean and so on. of the filtrate is still cloudy and then one at a time should be until clear so far.
following items can be used in daily life instead of the laboratory filter to filter the liquid. If gravel filter layer, carbon layer, fluffy cotton, gauze, etc..
2. activated carbon filter both to the liquid in the insoluble material, but also can absorb some of the dissolved impurities out.
3. methods of water purification:
and other methods.
if a single operation, the relative degree of purification from low to high order is :
4. contain more soluble calcium and magnesium compounds in water is called
water; containing or containing less soluble calcium and magnesium compounds in water is called
water.
�� the distinction between hard water and soft water Methods:
�� place long after the heating or the water produced is
scale water.
�� add soap to the water, little water is
bubble of water, a large number of bubbles is the emergence of water
water.
�� hard water to the life and production of the harm:
�� a waste of laundry soap with hard water, and washing dirty clothes, clothing, a long time will harden.
�� Boiler, with hard water boiler furring easy to make, not only a waste of fuel, in severe cases may cause an explosion.
�� water softening method:
�� life by boiling water or exposure.
�� Laboratory Preparation of distilled water in the methods used.
issue 4
love water
1. the total amount of water on the planet is large, but rarely available fresh water resources.
2. the nature of water, including marine water (of the total water storage golf ball
, and the water is rich in chemical resources, according to the current measurement, seawater contains a variety of chemical elements
), lake water, river water, groundwater, atmospheric water, biological water other.
3. the world is facing many countries and regions due to water crisis:
freshwater resources are not abundant, fresh water reserves of only about global
, available only about one of the
,
less than 1% of the total amount of water, but uneven distribution, more and more serious pollution.
of total water resources 2.8X1012m3, the world's No.
place. but only 2300m3 of water per capita is about, about water per capita for the world
, the world's No.
bit.
4. the main source of water pollution: industrial production wastewater discharge standards are not; agriculture, fertilizers, irrational use of pesticides; any sewage emissions.
5. love one hand, water is water conservation measures to improve water use efficiency; the other hand, to prevent water pollution.
6. to prevent and eliminate water pollution measures are:
( 1) reduce the production of pollutants.
(2) on the treatment of contaminated water to conform to emission standards.
(3) promote the use of manure in agriculture, rational use of fertilizers and pesticides.
( 4) centralized sewage treatment before discharge.
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