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General Inorganic Chemistry - Tay Do University - 14



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Because Na and K easily react violently with water, they are usually kept in oil.


General Inorganic Chemistry - Tay Do University - 14

Reaction with acid:

+ With dilute acids such as HCl, H 2 SO 4 : The reaction occurs vigorously and releases


H 2 SO 4 + 2M M 2 SO 4 + H 2

+ With acid radicals that have oxidizing properties such as H 2 SO 4 (above,n), HNO 3 , the element is reduced to form

acid to lowest value


c. State of nature


K + 10HNO 3 8KNO 3 + NH 4 NO 3 + 3H 2 O


Because of their high chemical activity, alkali metals do not exist in a single state.

substance that exists only in the compound state

- NaCl is abundant in seawater or in salt mines.

- NaCl. KC1 in the mineral silvinite.

- KCl.MgCl 2 .6H 2 O is a component of the mineral Carnallite.

- KNO 3 and NaNO 3 in saltpeter mine.

- Na 3 AlF 6 in cryolite

d. Preparation

- Electrolysis of molten chloride or hydroxide salts:

2NaCl 2Na + Cl 2 4KOH 4K + O 2 + 2H 2 O

- Today, sodium and potassium hydroxides are prepared by electrolysis (with

chloride salt solution, for example:

2NaCl + 2H 2 O 2NaOH + Cl 2 + H 2

e. Applications and roles of potassium and sodium compounds

Application:

NaOH is widely used in the production of soap, paper, sugar...

- NaHCO 3 is used in food and beverage processing... Na 2 CO 3 in the production of glass, ceramics, porcelain...


- Sodium is also used to prepare some metals that are difficult to melt such as titanium, zirconium and some other metals. Alloys of sodium and potassium are widely used in organic synthesis reactions... Alloys of lead with sodium and calcium are used as lubricants for train bearings.

- Potassium salts such as KNO 3 , KC1... are used as fertilizers for plants.

Role:

- Sodium is absorbed into the body mainly in the form of NaCl salt.

- Sodium exists in the body mainly in the form of chloride, bicarbonate and phosphate, partly combined with organic acids and proteins. Sodium also exists in intercellular spaces and in body fluids such as blood, lymph, etc.

- Plays a vital role: maintaining the concentration and volume of extracellular fluid. Na+ is the main ion outside the cell, so Na + disorders are always accompanied by water disorders.

- Potassium salt is often found in plant foods.

- In the body, K exists mainly inside glandular tissues, nerve tissues, and bone tissues.

bones and muscles in the form of chloride and bicarbonate salts

- Potassium plays an important role in metabolic processes, participating in the buffer system that regulates cell pH. Potassium helps regulate water and electrolyte balance, helping to maintain normal functioning, especially of the cardiovascular, muscular, digestive, and urinary systems.

- Potassium also helps the body produce protein from amino acids and convert glucose into glycogen (the body's main reserve polysaccharide), a major source of energy for all body activities.

B. MAGNESIUM (Mg), CALCIUM (Ca) AND BARIUM (Ba)

a. Structural characteristics

Elements: Mg, Ca, Ba are elements in group IIA.

The atomic radius is quite large and the nuclear charge is relatively small.

Atoms with 2 outer electrons: ns 2 (Mg 3s 2 , Ca 4s 2 and Ba 6s 2 ) so easily lose 2 electrons showing oxidation number +2.

M - 2e → M +2

They are highly active metals and have strong reducing properties (Only after group IA).

Atoms or compounds that burn to give characteristic colored flames: Mg – color

white, Ca - orange red, Ba - green.


b. Chemical properties

Reaction with oxygen: At room temperature creates a durable protective oxide layer.

2M + O 2 2MO

2Mg + O 2 2MgO

2Ca + O 2 2CaO

Ba when burned can give BaO2 .


Reaction with non-metals


Ba + O 2 BaO 2


+ With halogens (Cl 2 , Br 2 ) at room temperature:

M + Cl 2 MC1 2

+ With other non-metals such as S, C, P when heated, for example:

Ca + 2C CaC 2 (calcium carbide or calcium carbide) Reacts with water

- Ca and Ba easily react with water at room temperature:

M + 2H 2 O M(OH) 2 + H 2

- Mg reacts slowly with hot water to form a protective layer of slimy hydroxide:

Mg + 2H 2 O Mg(OH) 2 + H 2

However, this hydroxide layer can be dissolved if a little concentrated NH 4 C1 is added: Mg(OH) 2 + 2NH 4 Cl MgCl 2 + 2NH 3 + 2H 2 O

Reaction with acids

- Reaction with HCl, dilute H 2 SO 4 :

M + 2HC1 MC1 2 + H 2

- Reacts with concentrated HNO 3 and H 2 SO 4

With dilute HNO 3 : 4M + 10HNO 3 4M(NO 3 ) 2 + NH 4 NO 3 + 3H 2 O

With concentrated HNO3: M + 4HNO 3 M(NO 3 ) 2 + 2NO 2 + 2H 2 O

With concentrated H 2 SO 4 : M + 2H 2 SO 4 MSO 4 + SO 2 + 2H 2 O

c. State of nature

Exists in nature as minerals:


- Limestone CaCO 3 , gypsum CaSO 4 . 2H 2 O, apatite Ca 5 (PO 4 ) 3 F

- Magnesite MgCO 3 , carnalite KC1. MgCl 2 , MgCl 2 in sea water and in potassium salt mines.

- Dolomite CaCO 3 . MgCO 3 .

- Baritin BaSO 4 , Viterit BaCO 3 ...

d. Preparation

Simple

- Alkaline earth metals can be prepared by electrolysis of molten chloride salts:

MC1 2 M + Cl 2

- In addition, Mg can be prepared by the reaction using C to reduce MgO at 2000°C:

MgO + C Mg + CO

or use Fe - Si alloy to reduce MgO from dolomite at 1500°C

CaCO 3 . MgCO 3 → CaO, MgO → Mg + CaO. SiO 2

- Among the group IIA metals, magnesium is the most widely used, especially in the field of metallurgy. Mg is an important component of duralumin (alloy of Al and Mg) magnalium (alloy of Al, Mg and Mn) which is light and has very high mechanical strength.

Compound

Oxides of Mg, Ca, Ba are obtained by thermal decomposition of carbonate salts. Since ancient times, people have known how to burn limestone (CaCO 3 ) to obtain quicklime (CaO):


build

CaCO 3 → CaO + CO 2

When slaked with water, lime (Ca(OH) 2 ) is an important ingredient in construction.


e. Applications and roles of alkaline earth metal compounds Applications

- BaCl2 is easily soluble and is used as a reagent in qualitative and quantitative ion analysis.

SO 4 2- , CO 3 2- and preparation of some other salts of barium. Due to its strong toxicity, BaCl 2 is also

used as a pesticide.

- Anhydrous CaCl2 has the ability to absorb moisture so it is used to dry gases and organic liquids.

bases such as ether, benzene... However, do not use with alcohol because it dissolves in alcohol.


- BaSO 4 is a poorly soluble substance so it is non-toxic. It has a radiopaque effect due to its ability to

absorbs a lot of x-rays so it is used in X-ray technology.

- Burnt gypsum (CaSO 4 .H 2 O) when mixed with water has the ability to harden, so

used as molds, statues, and orthopedic plasters in medicine.

- MgSO4 is also known as acrid salt, easily soluble in water. In medicine it is used as a laxative.

- BaCO 3 and BaS salts are also insoluble salts but are very toxic to the body.

probably because it is dissolved by hydrochloric acid which is abundant in the stomach and intestines.

Biological meaning and role

- Ca2 + ions are of great importance to the body, especially in bone formation.

Animal bones contain about 80% Ca 3 (PO 4 ) 2 , 13% CaCO 3 .

- Calcium exists in serum in the form of phosphate and citrate salts. Ca 2+ ions stimulate heart activity and blood clotting.

- Calcium is introduced into the body through plant foods and milk.

Mg2 + ion is present in the composition of some enzymes and in the chlorophyll of green plants.

In natural water (groundwater, rivers, streams...) there are Ca 2+ and Mg 2+ ions.

is called hard water. Hard water causes great harm to technology and life.

7.1.2 NON-METALLIC ELEMENTS

A. HYDRO

a. Location and characteristics

- In the periodic table hydrogen can be classified into group IA or VIIA

- Hydrogen has 3 isotopes

1 2 3

1 H Protium 1 H deutterium 1 H Tritti

In which P accounts for a very large percentage

b. Chemical properties

Reducing properties of molecular hydrogen

- Molecular hydrogen is quite stable under normal conditions, it only decomposes into atoms at 5000°C.

H 2 2H

- Except for fluorine, the reactions of hydrogen with non-metals or compounds


All require heat, or light, or a catalyst.

For example:

H 2 + F 2 2HF (in the dark) H 2 + Cl 2 2HC1 (t° or as)

2H 2 + O 2 2H 2 O (t° or xt) 3H 2 + N 2 3NH 3 (with xt)

H 2 + CuO Cu + H 2 O (t°c ) H 2 + RCHO R'OH (with xt)

Reducing properties of atomic hydrogen

Atomic hydrogen (nascent hydrogen) is very chemically active. It can reduce many substances even at room temperature.

For example: 5H + MnO 4 - + 3H + Mn 2+ + 4H 2 O C 6 H 5 NO 2 + 6H C 6 H 5 NH 2 + 2H 2 O

Oxidation

Hydrogen reacts with active metals to form hydrides.

For example: H 2 + Na 2NaH

c. Water

Characteristics of water

- Has an angular structure (HOH angle = 104°30') O has sp 3 hybridization .

- Polar molecule (dipole moment μ = 1.84D), is a solvent that can dissolve many substances.

- Has the ability to form hydrogen bonds. Therefore, it has some different properties in terms of boiling point, melting point, heat capacity... compared to similar compounds such as H 2 S, H 2 Se...

- At 4°C, water has the highest density, while ice has the lowest density. That's because ice crystals have a rather hollow structure due to the combination of 4 molecules.

Chemical properties of water

Chemically, water is a very reactive substance. It can react with many oxides, non-metals and metals. In these reactions, water can play different roles.


- Water is both an acid and a base according to Bronsted (hydrolysis reactions) Acid: H 2 O + CH 3 COO - CH 3 COOH + OH -

Base: H 2 O + NH 4 + H 3 O + + NH 3

- Water is both an oxidizing agent and a reducing agent.

+ Oxidizing agent: 2H 2 O + 2Na 2NaOH + H 2

+ Reducing agent: 2H 2 O + 2F 2 4HF + O 2

- In many reactions, water acts as a catalyst. For example, the reaction between H 2 and O 2 hardly occurs, but if a trace of water is present, it will occur immediately. The reaction between Fe and Cl 2 only occurs clearly when H 2 O is present as a catalyst.

d. Natural state and preparation

Natural state

- Hydrogen is found in free form in the atmosphere.

- A large amount is in the form of inorganic and organic compounds

Preparation

Hydrogen is prepared by several methods :

Reaction of alkali metals and alkaline earth metals with water

2Na + 2H 2 O 2NaOH + H 2 Ca + 2H 2 O Ca(OH) 2 + H 2

Reaction between active metal and acid

Mg + 2H + H 2 + Mg 2+

Reaction of metals with alkalis

Zn + 2NaOH H 2 + Na 2 ZnO 2

Deoxygenation reaction of steam with red hot C or CO.

H 2 O + C H 2 + CO

H 2 O + CO H 2 + CO 2 xt: Fe 2 O 3

Electrolysis of aqueous solutions of acids or alkalis, of salts between strong acids and strong bases, is essentially the process of water electrolysis.

2H 2 O 2H 2 + O 2


In industry, large amounts of hydrogen are prepared by the reaction between CH 4

and steam at 1100°C in the presence of Ni catalyst.

CH 4 + H 2 O CO + 3H 2

H 2 O 2 is prepared from the peroxides of alkali or alkaline earth metals.

BaO 2 + H 2 SO 4 H 2 O 2 + BaSO 4

e. Some applications of H 2 , H 2 O 2 and the role of water

Application

- A large amount of hydrogen is used to synthesize NH 3 in the production of chemical fertilizers and

for catalytic hydrogenation of organic compounds such as fatty acids.

- Today H2 is still loaded into meteorological balloons.

Molecular hydrogen is not a poisonous gas, but it does not support life.

Role

- In compound form, hydrogen is present in the composition of organic compounds that create and maintain life, proteins, fats, and carbohydrates.

- Water is an important compound of hydrogen that is indispensable for life.

flora and fauna on the planet.

- Water used for daily life must be clear, colorless, odorless and tasteless, and must contain dissolved oxygen from the air.

- One liter of water must not contain more than 0.5 grams of mineral salts, heavy metals, nitrates (signs of rotting animals), sulfides or H2S , or microorganisms.

Ca2 + content must be low.

- Groundwater often meets these standards but is not sufficient. Therefore, in cities or residential areas, people have to use river water that has been treated in many steps. To disinfect water, people often use chlorine at a certain dose.

- H 2 O 2 has the ability to decompose into atomic oxygen which has strong oxidizing properties, so in medicine it is used to wash wounds. In industry, H 2 O 2 is used to bleach wool, silk, paper... without damaging the material.

- On the other hand, H 2 O 2 also has toxic effects on the body. Oxidation reactions

in the body is always accompanied by the production of a certain amount of H 2 O 2. The toxic effects of this H 2 O 2 are eliminated by the enzyme catalase present in the blood and some body fluids.

catalase

animal.

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