Physical and chemical changes

• Chemistry
• Secondary Education
• Age 12,13

Physical and Chemical Changes

Topic 6. Chemical Energetics 

26 February 2024

Our Learning Map

Our Learning Map

exercise mentally by completing classwork 6 to describe the extraction of iron in the blast furnace

- State the symbol equations for the extraction of iron from hematite

(a) C + O₂ → CO₂

(b) C + CO₂ → 2CO

(c) Fe₂O₃ + 3CO → 2Fe + 3CO₂

(d) CaCO₃ → CaO + CO₂ 

(e) CaO + SiO₂ → CaSiO₃

Recall

• (a) What are the three raw materials added to the top of the blast furnace?
• (b) What chemical reactions are involved in iron extraction from hematite?

Extraction of iron from hematite

• Coke burns in the hot air, forming carbon dioxide. The reaction is exothermic, giving off heat and heating the furnace.
•  At the high temperatures in the furnace, more coke reacts with carbon dioxide, forming carbon monoxide. Carbon dioxide has been reduced to carbon monoxide.
•  Carbon monoxide reduces the iron(III) oxide in the iron ore to form iron. This will melt and collect at the bottom of the furnace, where it is tapped off.  
• Limestone (calcium carbonate) is added to the furnace to remove impurities in the ore. The calcium carbonate in the limestone thermally decomposes to form calcium oxide. 
• The calcium oxide formed reacts with the silicon dioxide, an impurity in the iron ore, to form calcium silicate. This melts and collects as a molten slag floating on the molten iron tapped off separately. 

Classwork 6 - Extraction of iron

• Goal - Write the three raw materials added to the top of the blast furnace. Sequence (arrange) the steps in extracting iron from hematite by numbering them correctly. Write the word/symbol equations for the reactions in the arranged steps.
• Product/Output - Completed worksheet
• Standards - Correct responses.

Plenary Discussion

Physical and Chemical Changes

Topic 6. Chemical Energetics 

26 February 2024

Our Learning Map

Our Learning Map

exercise mentally by completing classwork 6 to describe the extraction of iron in the blast furnace

create a poster to show examples of physical and chemical changes and provide an explanation for your choice

Our Learning Map

analyse a video about the complete extraction process of iron from hematite in the blast furnace

discuss further the differences between physical and chemical changes during the hinge-point discussion

create a poster to show examples of physical and chemical changes and provide an explanation for your choice

Physical and Chemical Changes

Topic 6. Chemical Energetics 

26 February 2024

Chemical or Physical Change?

Correcting Misconception

All changes involving substances are chemical changes.

Correcting Misconception

All changes involving substances are chemical changes.

Physical and Chemical Changes

Topic 6. Chemical Energetics 

26 February 2024

Collaborative work - Physical and Chemical Changes Poster

• Goal and output - Create a poster (using colouring and art materials) to show examples of physical and chemical changes; include at least 2 reasons why your examples show physical and chemical changes
• Standards - examples of changes, artistic expression, reasons provided, neatness and presentation

Hinge-point discussion

• What have you learned from the activity?

Physical and Chemical Changes

Topic 6. Chemical Energetics 

26 February 2024

Closing: Lesson Key Points

Demo: Physical vs Chemical Change

• Observe.
• Write your observations.
• Share.