Carbon and Its Compounds | Chemistry Form 2

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Carbon and Its Compounds - Chemistry Form 2

CARBON AND ITS COMPOUNDS

In this lesson, we will discuss properties of carbon and carbon (IV) oxide.

Pure carbon exists in two forms diamond and graphite. The existence of an element in more than one form in the same state is called allotropy.Allotropes are different forms of the same element that exist in the same state such as graphite and diamond.Carbon also exists in impure form. These include: Charcoal, soot, coal and coke.

By the end of the lesson, you should be able to:

Define allotropy and allotropes.

Describe laboratory preparation of carbon (IV) oxide .

State the properties of carbon (IV) oxide and state uses of carbon (IV) oxide.


Burning magnesium continues to burn in a gas jar of carbon (IV) oxide forming a white powder and black solid. The white powder is magnesium oxide while the black solid is carbon. Burning magnesium produces a lot of heat which splits the carbon (IV) oxide to carbon and oxygen. The oxygen gas supports burning of magnesium.


Carbon (IV) oxide reacts with sodium hydroxide solution to form sodium hydrogen carbonate and solution rises up in the inverted gas jar.The gas reacts with sodium hydroxide solution to form sodium carbonate.

Equation

2NaOH(aq) + CO2(g) w Na2CO3(s)

Similarly, carbon (IV) oxide dissolves in water to form weak carbonic acid.

Equation

CO2(g) + H2O(l) w H2CO3(aq)

Carbon (IV) oxide turns moist blue litmus paper to red while red litmus does not

change.The gas is acidic. Burning magnesium continues to burn in a gas jar of

carbon (IV) oxide forming a white powder and black solid. Carbon (IV) oxide

reacts with sodium hydroxide solution to form sodium hydrogen carbonate

and solution rise up in the inverted gas
jar.Similarly, carbon (IV) oxide

dissolves in water to form weak carbonic acid.

The following are some of the uses of carbon (IV) oxide.

In refrigeration:solid carbon (IV) oxide (dry ice) sublime and causes cooling.


Used in carbonated drinks


Making of baking powder (sodium hydrogen carbonate)

Used in the solvay process to manufacture sodium carbonate

Carbon (IV) oxide is used in fire extinguishers. This is because it does not support combustion.

Fire extinguisher

CARBON (II) OXIDE

In this lesson, we will discuss preparation, properties of carbon (II) oxide and the solvay process.

Carbon (II) oxide is a poisonous gas therefore it should be prepared in a fume chamber.



Fume chamber

By the end of the lesson, you should be able to

i) Describe laboratory preparation of carbon (II) oxide

ii) State the properties of carbon (II) oxide

iii) Describe the manufacture of sodium carbonate by solvay process


Carbon (II) oxide can be prepared by dehydrating sodium methanoate and by concentrated sulphuric acid .Arrange the apparatus as shown.

The flow chart shows the solvay process. Click on each of the towers to understand the processes which take place.

Carbon (II) oxide burns with a blue flame forming carbon (IV) oxide gas as shown.

2CO(g) + O2(g) w2 CO2(g)

When charcoal burns in a Jiko, there are three reactions which occur.


Carbon (II) Oxide reduces heated Copper (II) oxide to Copper metal while it is oxidized to Carbon (IV) oxide.

CuO(g) + CO(g) w Cu(s) + CO2(g)


Carbon (II) Oxide also reduces oxides of Zinc, Lead and Iron to their respective metals and is itself oxidized to Carbon (IV) oxide.Carbon (II) Oxide cannot reduce oxide of Magnesium and Aluminium because they are higher in the reactivity series.Carbon (II) oxide is therefore a strong reducing agent. The following equations shows the products formed.

ZnO(s) + CO(g) w Zn(s) + CO2(g)

PbO(s) + CO(g) wPb(s) + CO2(g)

Fe2O3(s) + 3CO(g) w 2 Fe(s) + 3CO2(g)



Manufacture of Sodium Carbonate

Sodium carbonate can be manufactured industrially in two ways:-
i) Extraction from trona
ii) Solvay process


ACTIVITY

Manufacture of glass

Water treatment



Treated water

Refining of metals



Jewellery from refined metals

Manufacture of soap

Manufacture of paper.


Step1:Sources of carbon (IV) oxide


A mixture of carbon and calcium carbonate is roasted in kiln to produce calcium Oxide and carbon (IV) oxide.

CaCO3(s) w CaO(s) + CO2(g)

Step 2 :sources of ammonia
Ammonia is obtained from the haber process.Calcium oxide produced in the limestones kiln is combined with water (slaked) and mixed with the filtrate of ammonium chloride to produce ammonia gas ,water and calcium chloride.

Ca(OH)2(aq)+2NH4Cl2(aq)w CaCl2(aq)+H2O(l)+2NH3(g)

 

Step3
Ammonia is dissolved in brine in the Solvay tower to produce ammoniated brine in the Solvay tower to produce ammoniated brine .The reaction is very exothermic. The ammoniacal brine is then pumped into the carbonator from the top while carbon (IV) oxide is pumped from the base. Sodium hydrogen carbonate is filtered off.

NH3(g)+CO2(g)+NaCl(aq)+H2O(l)wNaHCO3(aq)+NH4Cl(aq)

Step 4

Sodium hydrogen carbonate is filtered off, dried and heated to form sodium carbonate.

NaHCO3(s) w Na2CO3(s) + CO2(g) + H2O(l)

The Carbon (IV) oxide and water produced is recycled

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