Answers:
1. Fe + S → FeS
2. H₂ + Cl₂ → 2 HCl
3. 2 Mg + O₂ → 2 MgO
4. O₂ + 2 H₂ → 2 H₂O
5. 2 HgO → 2 Hg + O₂
6. Ca + 2 H₂O → Ca(OH)₂ + H₂
7. CH₄ + 2 O₂ → CO₂ + 2 H₂O
Step by step solution:
1. Fe + S → FeS
In this chemical equation we have:
On the left side: On the right side:
Fe: 1 atom Fe: 1 atom
S: 1 atom S: 1 atom
We have the same quantity of atoms on both sides of the equation, then the equation is balanced.
2. H₂ + Cl₂ → HCl
In this chemical equation we have:
On the left side: On the right side:
H: 2 atoms H: 1 atom
Cl: 2 atoms Cl: 1 atom
The equation is not balanced.
If we multiply the molecule of HCl on the right side of the equation by 2, we would get 2 H atoms and 2 Cl atoms on the right side:
H₂ + Cl₂ → 2 HCl
3. Mg + O₂ → MgO
In this chemical equation we have:
On the left side: On the right side:
Mg: 1 atom Mg: 1 atom
O: 2 atoms O: 1 atom
The equation is not balanced.
To get 2 O atoms on the right side of the equation, we must multiply the molecule of MgO by 2:
Mg + O₂ → 2 MgO
Now we have 2 Mg atoms on the right side, then we must multiply by 2 Mg on the left side of the equation:
2 Mg + O₂ → 2 MgO
4. O₂ + H₂ → H₂O
In this chemical equation we have:
On the left side: On the right side:
O: 2 atoms O: 1 atom
H: 2 atoms H: 2 atoms
The equation is not balanced.
To get 2 O atoms on the right side, we must multiply the molecule of H₂O
by 2:
O₂ + H₂ → 2 H₂O
Now we have 2(2)=4 H atoms on the right side and only 2 H atoms on the left side, then we must multiply the molecule of H₂ on the left side by 2:
O₂ + 2 H₂ → 2 H₂O
5. HgO → Hg + O₂
In this chemical equation we have:
On the left side: On the right side:
Hg: 1 atom Hg: 1 atom
O: 1 atom O: 2 atoms
The equation is not balanced.
To get 2 O atoms on the left side, we must multiply the molecule of HgO
by 2:
2 HgO → Hg + O₂
Now we have 2 Hg atoms on the left side and only 1 Hg atom on the right side, then we must multiply Hg on the left side by 2:
2 HgO → 2 Hg + O₂
6. Ca + H₂O → Ca(OH)₂ + H₂
In this chemical equation we have:
On the left side: On the right side:
Ca: 1 atom Ca: 1 atom
H: 2 atoms H: 2+2=4 atoms
O: 1 atom O: 2 atoms
The equation is not balanced.
To get 2 O atoms on the left side, we must multiply the molecule of H₂O by 2:
Ca + 2 H₂O → Ca(OH)₂ + H₂
And we get 2(2)=4 H atoms on the left side. The equation is balanced.
7. CH₄ + O₂ → CO₂ + H₂O
In this chemical equation we have:
On the left side: On the right side:
C: 1 atom C: 1 atom
H: 4 atoms H: 2 atoms
O: 2 atoms O: 2+1=3 atoms
The equation is not balanced.
To get 4 H atoms on the right side, we must multiply the molecule of H₂O by 2:
CH₄ + O₂ → CO₂ + 2 H₂O
Now we have 2 O atoms on the left side, and 2+2=4 O atoms on the right side, then we must multiply the molecule of O₂ on the left side by 2:
CH₄ + 2 O₂ → CO₂ + 2 H₂O
