Answers:
8. Na₂O₂ + H₂(SO₄) → Na₂(SO₄) + H₂O₂
9. N₂ + 3 H₂ → 2 NH₃
10. 4 Al + 3 O₂ → 2 Al₂O₃
11. 4 KMnO₄ → 2 K₂O + 4 MnO + 5 O₂
Step by step solution:
8. Na₂O₂ + H₂(SO₄) → Na₂(SO₄) + H₂O₂
In this chemical equation we have:
On the left side: On the right side:
Na: 2 atoms Na: 2 atoms
O: 2+4=6 atoms O: 4+2=6 atoms
H: 2 atoms H: 2 atoms
S: 1 atom S: 1 atom
We have the same quantity of atoms on both sides of the equation, then the equation is balanced.
9. N₂ + H₂ → NH₃
In this chemical equation we have:
On the left side: On the right side:
Na: 2 atoms Na: 1 atom
H: 2 atoms H: 3 atoms
The equation is not balanced.
We need to multiply the molecule of NH₃ on the right side of the equation by 2 to get 2 Na atoms on the right side:
N₂ + H₂ → 2 NH₃
Now, we have 2(3)=6 H atoms on the right side of the equation, then we must multiply the molecule of H₂ on the left side by 3 to get 3(2)=6 H atoms on the left side of the equation:
N₂ + 3 H₂ → 2 NH₃
10. Al + O₂ → Al₂O₃
In this chemical equation we have:
On the left side: On the right side:
Al: 1 atom Al: 2 atoms
O: 2 atoms O: 3 atoms
The equation is not balanced.
The least common multiple between the quantity of atoms of O of the left side (2) and the right side (3) is 2*3=6, then let's multiply the molecule of O₂ on the left side by 3 and the molecule of Al₂O₃ on the right side by 2 to get 6 O atoms on both side of the equation:
Al + 3 O₂ → 2 Al₂O₃
Now we have 2(2)=4 Al atoms on the right side of the equation and only 1 Al atom on the left side, then let's multiply the Al atom on the left side by 4:
4 Al + 3 O₂ → 2 Al₂O₃
11. KMnO₄ → K₂O + MnO + O₂
In this chemical equation we have:
On the left side: On the right side:
K: 1 atom K: 2 atoms
Mn: 1 atom Mn: 1 atom
O: 4 atoms O: 1+1+2=4 atoms
The equation is not balanced
If we suppose that the coefficients are:
a KMnO₄ → b K₂O + c MnO + d O₂
We have on the left side "a" Mn atoms and on the right side "c" Mn atoms, and they must be equal then a=c:
a KMnO₄ → b K₂O + a MnO + d O₂
We have "a" K atoms on the left side and b(2)=2b K atoms on the right side, then a=2b
And we have on the left side a(4)=4a O atoms and on the right side
b+a+d(2)=b+a+2d O atoms, and they must be equal, then:
4a=b+a+2d
and a=2b, replacing in the equation above:
4(2b)=b+2b+2d
8b=b+2b+2d
Adding like terms on the left side of the equation:
8b=3b+2d
Solving for d: Subtracting 3b from both sides of the equation:
8b-3b=3b+2d-3b
5b=2d
Dividing both sides of the equation by 2:
5b/2=2d/2
5b/2=d
d=5b/2
Then b must be an even number to get a whole number for d, using the least even number for b=2
d=5(2)/2→d=5
and a=2b=2(2)→a=4
Then the equation balanced is:
4 KMnO₄ → 2 K₂O + 4 MnO + 5 O₂
Now we have:
On the left side: On the right side:
K: 4 atoms K: 2(2)=4 atoms
Mn: 4 atoms Mn: 4 atoms
O: 4(4)=16 atoms O: 2+4+5(2)=2+4+10=16 atoms
The equation is balanced
