notes on metals and reactions with water_acid_and_steam

7/30/2019 Notes on Metals and Reactions With Water_acid_and_steam

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An oxide layer is formed at the surface of these metals when exposed to air.

Metals in their pure state have a shiny surface and are good reflectors of light.

This property of metals is called metallic luster. Since metals have luster, they

are used to make jewellery.

Gold, in its pure form is the most lustrous metal since it is not affected by air andmost reagents. Heat, moisture, oxygen, and most corrosive agents have very

little chemical effect on gold, making it well-suited for use in jewellery.

Metal that will melt in your hands Gallium: Gallium has a melting point of 30

degrees. Gallium is a liquid over a wide range of temperature that is why gallium

has found use in thermometers and manometers for high temperature

measurements

Tungsten melts at a very high temperature of 2400 degrees Celsius: Metals tendto have high melting point because of the strength of the metallic bond. The

strength of the bond varies from metal to metal and depends on the number of

electrons, which each atom can contribute during bond formation. Because of

high melting point, tungsten is used as filaments in light bulb and cathode ray

tube

Metallic Lattice; The force of attraction between the sea of electrons and

positive metal ions is termed as metallic bonding.

Metals are good conductors of electricity. Among the metals silver has the

highest electrical conductivity, but due to its high cost and tarnish-ability it hasnot been widely used for electrical purposes. This explains why wires are usually

made of metals.

Vessels made of aluminum are more popularly used than that made of copper as

aluminium is light and inexpensive in comparison to copper.

Why are metals good conductors of heat and have high melting pointheat

transfer works on the same principle as that of electricity conduction. Heat

energy is picked up by the electrons as additional kinetic energy. The energy is

transferred throughout rest of the metal by the moving electrons. This is the

reason why metallic vessels have wooden handles.

*Usually, good conductors of heat are good conductors of electricity. For

example, the metal copper is both a good conductor of heat and electricity.

However, diamonds are different. In spite of being a god conductor of heat,

diamonds are non-conductors of electricity. This is because, unlike metals,

diamonds do not have mobile electrons which are required to transfer electricity.

The rion and aluminium pieces can be flattened, because metals are malleable

but the coal block and pencil lead broke down since they are brittle. Malleability

is the ability of metals to deform and flatten upon the application of compressiveforce. It is because of the property of malleability that metals can be beaten into


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sheets. An aluminium foil is one of the most common examples that exhibit the

property of malleability in metals.

Gold, most ductile.

Metals react differently with different reagents. Degree of reactivity varies with

different metals.

Potassium being the most reactive reacts violentsly with water. Sodium being

less reactive than potassium reacts less violently with water. The next in order

are Calcium and magnesium. Zinc and Iron does not react with water, but they

react readily when exposed to steam. Leader, copper and silver are the least

reactive metals.

IN DILUTE HYDROCHLORIC ACID

Potassium and sodium reacts explosively in dilute hydrochloric acid.

2K (s) + 2HCl (aq) 2KCl (aq) + H2 (g)

2Na (s) + 2HCl (aq) 2NaCl (aq) + H2 (g)

Calcium reacts vigorously to give calcium chloride and hydrogen gas.

Ca(s) +2HCl(aq) CaCl2 (aq) + H2 (g)

Magnesium reacts to form magnesium chloride and hydrogen gas.

Mg(s)+2HCl(aq)MgCl2(aq)+H2(g)

Zinc reacts moderately fast to give zinc chloride and hydrogen gas.

Zn(s)+2HCl(aq)ZnCl2 (aq) +H2 (g)

Iron reacts slowly to give iron (ii) chloride and hydrogen gas.

Fe(s) +2HCl (aq) FeCl2 (aq) + H2 (g)

Lead, copper and silver show no reaction.

Reactivity series

When you dip an iron nail into aqueous copper (ii) sulphate, a displacement

reaction takes place whereby a more reactive metal, in this case, iron displaces

the less reactive metal, copper from its salt, copper sulphate. Fe(s) +CuSO4 (aq)

FeSO4 (aq) +Cu(s)

KNaCaMgZnFePbCuAg (Please stop calling my zebra in laters

class + Gold)


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In a metal displacement reaction, the more reactive metal is oxidized while the

less reactive metal is reduced.

E.g. Mg(s) + Cu (II) 2+ (aq) Cu(s) + Mg2+ (aq)

E.g. Cu (s) + 2Ag+ 2Ag (s) + Cu2+ (aq)

Displacement reactions help in forming a protective layer on the surface of more

reactive metals to help prevent it from corrosion.

Thermit process

E.g. 2Al (s) + Fe2O3 (s) Al2O3 (s) + 2Fe (I)

Aluminium is more reactive than iron. It takes away the oxide ion, O2-, form iron

three (III) oxide to form aluminium oxide. Iron three (III) oxide is thus reduced to

molten iron. Since the iron formed is in the molten state, it can be used to weld

pieces of metal together.

The more reactive a metal is, the more likely it is to form positively charged ion.

This reaction shows that Aluminium is more reactive than iron.

Most metals react with dilute acids to form salts and hydrogen gas

A metal which is higher in reactivity series has a greater tendency to form its

positive ions.

The thermal stability of metal carbonates is related to the position of the metal in

the reactivity series. By comparing the speed at which the metal carbonates

decompose under strong heating, the reactivity of the metals can be

determined.

Na2CO3 does not decompose on heating, and thus it undergoes no reaction.

Same is the case with K2CO3.

CaCO3 decomposes into metal oxide and formed CO2 on heating, which turnslimewater chalky. Similarly, CaCO3, MgCO3, ZnCO3, PbCO3 and CuCO3

decompose into their respective metal oxides and form CO2 on heating, which

turns limewater chalky.

Ag2CO3 decomposes into silver and forms CO2 on heating, which turns

limewater milky.

Pure metals are soft, corrode easily and are brittle.

In order to overcome these disadvantages, metals are mixed with other metals

or non-metals to put them into use. ALLOYS!!! XD


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notes on metals and reactions with water_acid_and_steam

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