2.3 Balancing reaction equations

• Scheikunde
• Middelbare school
• vwo
• Leerjaar 3

What do you know about balance?

Learning goals

At the end of the lesson you can:

• Balance a chemical equation

Balance

Atoms

left and right

index not, coëfficiënt yes

don't write 1

Step 1 Reaction equation

Aluminiumoxide -> aluminium + oxygen

Al₂O₃ -> Al + O₂

Step 2 Count atoms

Aluminiumoxide -> aluminium + oxygen

Al₂O₃ -> Al + O₂

Al	2		Al	1
O	3		O	2

Step 3 Right and left equal (1)

Aluminiumoxide -> aluminium + oxygen

Al₂O₃ -> 2 Al + O₂

Al	2		Al	2
O	3		O	2

Step 3 Right and left equal (2)

Aluminiumoxide -> aluminium + oxygen

Al₂O₃ -> 2 Al + 1.5 O₂

Al	2		Al	2
O	3		O	3

Stap 3 Whole numbers

Aluminiumoxide -> aluminium + oxygen

2 Al₂O₃ -> 4 Al + 3 O₂

Al	4		Al	4
O	6		O	6

phet.colorado.edu

Is this reaction balanced?

1. Yes
2. No

Make the reaction equation balanced.

2P+3Cl​2​​→......PCl​3​​

1. 1
2. 2
3. 3
4. 4

What is the balanced equation?

1. CH​4​​(g)+O​2​​(g)→CO​2​​(g)+H​2​​O(l)
2. CH​4​​(g)+O​2​​(g)→CO​2​​(g)+2H​2​​O(l)
3. CH​4​​(g)+2O​2​​(g)→CO​2​​(g)+H​2​​O(l)
4. CH​4​​(g)+2O​2​​(g)→CO​2​​(g)+2H​2​​O(l)

What is the balanced equation?

1. Fe2O3(s) + C(s) --> Fe(l) + CO2(g)
2. Fe2O3(s) + 2 C(s) --> 2 Fe(l) + 2 CO2(g)
3. 2 Fe2O3(s) + 3 C(s) --> 4 Fe(l) + 3 CO2(g)
4. 3 Fe2O3(s) + 4 C(s) --> 6 Fe(l) + 4 CO2(g)

Making exercise

Make 34a-c (10 min in silence)

Finished? Make 27, 28, 29, 34d - l

Making exercise

Make 34d - l (10 min in silence)

Finished? Make 27, 28, 29

Reflection

At the end of the lesson you can:

• Balance a chemical equation