Lesson 1.2. Chemical properties of ​carbon 

Lesson learning objectives 

  Explain the  reactions of carbon with different elements and compounds.

Activity 1.2.1 

1. After watching the video, answer the questions ​that follows. 

a) What type of reaction burning charcoal is?

b) What are the products of the above reaction?

c) Beside the yellow color of burning charcoal, which  ​

   other color observed on the top of charcoal stove? 

1. Complete the following equation: 

C + ZnO → 

Key question 

What are the reactions of carbon? 

click here to watch the video 

Burning Charcoal 

ANSWER

a) What type of reaction is burning charcoal?

Burning charcoal is a combustion reaction. Combustion reactions typically involve a substance reacting with oxygen to produce heat and light.

b) What are the products of the above reaction?

The primary product of burning charcoal (carbon) in the presence of sufficient oxygen is carbon dioxide (CO₂). If the oxygen supply is limited, carbon monoxide (CO) can also be produced.

c) Besides the yellow color of burning charcoal, which other color is observed on the top of the charcoal stove?

Besides the yellow color, you might observe a blue flame on the top of the charcoal stove. The blue flame indicates the presence of carbon monoxide (CO) burning to form carbon dioxide (CO₂).

Complete the following equation:

C+ZnO→CO+Zn

Activity 1.2.2  

Study of carbon reactions 

1. By using the appropriate symbols complete  
   ​the following reactions. Discuss your findings with  
   ​another pair.                                                                                                                                                                                                                             a) Carbon + oxygen→                                                                                                                                                                                                         b) Carbon + copper (II) oxide→

          c) By the help of chemical equations and using carbon as a fuel differentiate between complete and ​incomplete combustion. 

          d)  Why carbon is a reducing agent?  

Possible Answer

a) Carbon + Oxygen → Carbon Dioxide

The chemical equation for this reaction is: C+O2→CO2C + O_2 rightarrow CO_2C+O2​→CO2​

b) Carbon + Copper (II) Oxide → Carbon Dioxide + Copper

The chemical equation for this reaction is: C+CuO→CO2+CuC + CuO rightarrow CO_2 + CuC+CuO→CO2​+Cu

c) Complete vs Incomplete Combustion with Carbon as Fuel:

Complete Combustion:

• Involves burning carbon (C) in excess oxygen (O2).

• Equation: C+O2→CO2C + O_2 rightarrow CO_2C+O2​→CO2​

• Products: Carbon dioxide (CO2) only.

• Occurs with sufficient oxygen supply, resulting in maximum energy release and clean burning.

Incomplete Combustion:

• Occurs when there’s insufficient oxygen supply.

• Equation: 2C+O2→2CO2C + O_2 rightarrow 2CO2C+O2​→2CO

• Products: Carbon monoxide (CO) and carbon (soot).

• Results in less energy release compared to complete combustion and can produce harmful carbon monoxide gas.

d) Why Carbon is a Reducing Agent:

Carbon acts as a reducing agent because it has a tendency to donate electrons or reduce the oxidation state of other elements in reactions. In combustion and other chemical processes, carbon can reduce metal oxides (like copper oxide in part b)) by donating electrons to them, thereby reducing them to their elemental form (e.g., copper from copper oxide). This ability to donate electrons makes carbon useful in various industrial processes and metallurgy where reduction reactions are crucial.

c) Reaction with metal oxides

Carbon reduces metal oxides below it in the reactivity series. 

The reducing property of carbon is used in the extraction of metals such as iron, lead and zinc from their oxides. 

For example, carbon reacts with iron (III) oxide as follows: 

This is a redox reaction where carbon reduces iron from its oxide and is itself oxidised to carbon dioxide. The ​reaction is exothermic and hence continues even after ​heating is stopped. 

a) Reaction with oxygen (combustion)

All forms of carbon react with the oxygen in the air to form oxides. 

• In plenty of oxygen, carbon burns to form carbon dioxide. 

Carbon + Oxygen → Carbon dioxide + heat 

C (s)      +  O2 (g)     →      CO2 (g)        + heat 

• In limited supply of air, carbon burns forming carbon monoxide gas. 

Carbon + Oxygen → Carbon monoxide + heat 

2C (s)      +  O2 (g)     →      2CO (g)         + heat 

Carbon dioxide is an acidic gases while carbon monoxide is a neutral gas. 

1. b)Reaction with carbon dioxide

Carbon dioxide reacts with heated charcoal to form carbon ​monoxide gas. Carbon monoxide in turn burns with blue ​flame.  

CO2 (g)      +  C (s)     →      2 CO (g) 

1. d) Reaction with concentrated nitric acid and concentrated sulphuric acid

Carbon does not react with dilute acids. However,  

• Carbon reacts with concentrated sulphuric acid to form carbon dioxide, sulphur dioxide and water.  

• With concentrated nitric acid, it forms carbon dioxide, nitrogen dioxide and water as shown below: 

Carbon + Sulphuric acid →Carbon dioxide + Sulphur dioxide + water 

C(s)       + 2 H2SO4 (aq)     → CO2 (g)              + 2 SO2 (g)        + 2 H2O (l) 

Carbon + nitric acid →Carbon dioxide + nitrogen dioxide + water 

C(s)       + 4 HNO3 (l) → CO2 (g)              + 4 NO2 (g)             + 2 H2O (l) 

Activity 1.2.3 

Sodium readily reacts with oxygen to form sodium oxide while carbon reacts with oxygen upon heating. 

1. Write chemical equations for the reactions described ​above. 
2. Is it a good idea to extract sodium from its oxide using ​carbon as a reducing agent? Explain 

      Formative assessment 

1. Carbon reacts with oxygen according to the  
   ​equations below: 

1. C (S) + O2 (g) → CO2 (g) + heat 
2. 2C (S) + O2 (g) → 2CO (g) + heat 

(a) What condition is required in (i) and (ii) above? 

(b) What does heat in the equations indicate ​about  

      the two  reactions above? 

Lesson summary 

• Carbon burns in plentiful and limited supply of oxygen to produce carbon dioxide and carbon monoxide ​respectively. 
• Carbon reduces carbon dioxide to carbon monoxide. 
• Carbon reduces oxides of metals below it in reactivity ​series. 
• Carbon reacts with concentrated nitric acid and  
  ​concentrated sulphuric acid but not dilute acids. 
•  Carbon is a reducing agent. 

Homework 

Carbon reacts with carbon dioxide according to the equation below. 

CO2 (g) + C(s)  → 2CO (g) 

1. Identify the substance that loses oxygen and the one that gains oxygen from the reaction above  
2. Which one among CO2 and C is a reducing agent? 

xxx