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- Metals under hydrogen do not react with water or acids. They are extracted by heat or physically.
- Metals above carbon will react with water and they are extracted using electrolysis.
- Metals in between hydrogen and carbon react with acids to form a salt and hydrogen.
- Going from bottom to top, the metals will tarnish more easily, lose electrons more readily to form positive ions, and increase in reactivity.
Reduction and Oxidation
When substances react with oxygen, they form new substances called oxides. These reactions in which a substance gains oxygen is called oxidations.
Sometimes, it is possible to remove oxygen from an oxide. For example, if mercury oxide is heated strongly, it will decompose to mercury and oxygen.
Mercury oxide -> mercury + oxygen
Reactions like this in which a substance loses oxygen are called reductions.
Reduction is the loss of oxygen. Oxidation is the gain of oxygen. Also, reduction is the gain of electrons. Oxidation is the loss of electrons.
How do metals react with water?
Reactive metals take oxygen from water to form their oxides. Hydrogen is also a product.
Example: Sodium + Water -> Sodium oxide + Hydrogen
The oxides of reactive metals react further with water forming the metal hydroxide.
Example: Sodium oxide + water -> sodium hydroxide
Types of reactions according to metals
Sinks in the water. Stream of hydrogen is produced. The solution become alkaline and cloudy.
Tiny bubbles of hydrogen appear on the surface of the magnesium. The solution becomes alkaline.
A violent reaction occurs. The potassium skates over the surface. It then burns with a flame. Hydrogen and potassium hydroxide form.
A vigorous reaction occurs. It skates about the water surface. Hydrogen and sodium hydroxide form.
Reaction of metals (equation)
Metal + water (hydrogen oxide) -> metal oxide + hydrogen.
In these reactions, the metal is oxidised to metal oxide. The water is reduced to hydrogen.
Reaction of metals in dilute acid
Solution boils with fast production of bubbles
Steady formation of bubbles
Therefore, magnesium is most reactive and copper is the least reactive.
Displacement of metals
zinc + sulphuric acid -> zinc sulphate + hydrogen.
In this case, zinc has displaced hydrogen from the sulphuric acid.
A more reactive metal displaces less reactive metals from their compounds.
Example: Zinc can displace lead, copper, and silver, but not magnesium.
These reactions in which one metal displaces another is called displacement reactions.
Reduction in extraction of metals
Obtaining the metal involves converting the metal ions (M2+) to metal atoms (M). This process involves the gain of electrons which is reduction.
M2+ 2e- -> M
Metals in the middle of the reactivity series are obtained by reducing their oxides with carbon (coke) or carbon monoxide. In these cases, carbon/monoxide are more reactive than the metals, thus they can remove oxygen from the metal oxide, leaving metal.
Metals at the top of the reactivity series cannot be obtained by reduction. These metals are obtained from their ores using electricity. The process is called electrolysis.
Reactive metals are extracted by electrolysis of their molten (melted) compounds.
1) The ore is melted and electrodes are placed
in the liquid.
2) The ions are free to move in the liquid and
are attracted to either the negative or
3) The electrons are either taken or provided
and the metal is collected.
Extracting iron from iron ore
Iron is obtained from impure iron oxide. The process of extraction is carried out in blast furnaces.
1) Ore, coke (carbon), and limestone is put in the furnace.
2) Blasts of hot air are blown in the bottom of the furnace.
3) Oxygen in the blasts of the air reacts with coke to form carbon monoxide.
Carbon + oxygen -> carbon monoxide
4) As the carbon monoxide rises up the furnace, it reacts with the iron ore to form iron.
Iron oxide + carbon monoxide -> iron + carbon dioxide
Limestone breaks down sandy deposits and forms slag. The slag cleans iron, forming cast iron (pure iron.)
Solutions formed by nonmetal and metal oxides
Non metal oxides give acidic solution.
Metal oxides give alkaline solution.
Reactive metals in nature
They contain higher than normal amounts of nitric and sulfuric acids. They are caused by pollution and natural sources such as volcanoes. They accelerate the decay of buildings, causes acidification of lakes and contributes to the damage of trees, and harm public health.
If one substance loses electrons in a reaction, then another substance must gain them. These reactions are called redox reactions (reduction + oxidation)
All the reactions of metals with non-metals are redox reactions. In these reactions, the metal (M) is always oxidized to form positive metal ions and the non-metal (X) is reduced to form negative ions.
Example: M + X -> M2+ + X2-.
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