Question

balance the equations by adding whole numb

1. h₂ + o₂ → h₂o
2. n₂ + h₂ → nh₃
3. c₃h₈ + o₂ → co₂ + h₂o
4. fe + o₂ → fe₂o₃
5. al + hcl → alcl₃ + h₂
6. kclo₃ → kcl + o₂
7. na + h₂o → naoh + h₂

Explanation:

Step1: Balance hydrogen and oxygen in $H_2 + O_2

ightarrow H_2O$
There are 2 oxygen atoms on the left - hand side and 1 on the right - hand side. Multiply $H_2O$ by 2 to get 2 oxygen atoms on the right. Then multiply $H_2$ by 2 to balance hydrogen. The balanced equation is $2H_2+O_2 = 2H_2O$.

Step2: Balance nitrogen and hydrogen in $N_2 + H_2

ightarrow NH_3$
There are 2 nitrogen atoms on the left - hand side, so multiply $NH_3$ by 2. Then there are 6 hydrogen atoms on the right - hand side, so multiply $H_2$ by 3. The balanced equation is $N_2 + 3H_2=2NH_3$.

Step3: Balance carbon, hydrogen and oxygen in $C_3H_8 + O_2

ightarrow CO_2 + H_2O$
First, balance carbon. Since there are 3 carbon atoms in $C_3H_8$, multiply $CO_2$ by 3. There are 8 hydrogen atoms in $C_3H_8$, so multiply $H_2O$ by 4. The number of oxygen atoms on the right - hand side is $3\times2 + 4\times1=10$. So multiply $O_2$ by 5. The balanced equation is $C_3H_8+5O_2 = 3CO_2 + 4H_2O$.

Step4: Balance iron and oxygen in $Fe + O_2

ightarrow Fe_2O_3$
The least common multiple of 2 (oxygen atoms in $O_2$) and 3 (oxygen atoms in $Fe_2O_3$) for oxygen is 6. Multiply $O_2$ by 3 and $Fe_2O_3$ by 2. Then multiply $Fe$ by 4. The balanced equation is $4Fe+3O_2 = 2Fe_2O_3$.

Step5: Balance aluminum, chlorine and hydrogen in $Al + HCl

ightarrow AlCl_3 + H_2$
To balance chlorine, since there are 3 chlorine atoms in $AlCl_3$, multiply $HCl$ by 3. But then hydrogen is unbalanced. Multiply $HCl$ by 6, $AlCl_3$ by 2, $H_2$ by 3 and $Al$ by 2. The balanced equation is $2Al + 6HCl=2AlCl_3+3H_2$.

Step6: Balance potassium, chlorine and oxygen in $KClO_3

ightarrow KCl + O_2$
The least common multiple of 2 (oxygen atoms in $O_2$) and 3 (oxygen atoms in $KClO_3$) for oxygen is 6. Multiply $KClO_3$ by 2 and $O_2$ by 3. Then multiply $KCl$ by 2. The balanced equation is $2KClO_3=2KCl + 3O_2$.

Step7: Balance sodium, hydrogen and oxygen in $Na + H_2O

ightarrow NaOH + H_2$
Multiply $Na$ by 2, $H_2O$ by 2, $NaOH$ by 2. The balanced equation is $2Na+2H_2O = 2NaOH + H_2$.

Answer:

1. $2H_2+O_2 = 2H_2O$
2. $N_2 + 3H_2=2NH_3$
3. $C_3H_8+5O_2 = 3CO_2 + 4H_2O$
4. $4Fe+3O_2 = 2Fe_2O_3$
5. $2Al + 6HCl=2AlCl_3+3H_2$
6. $2KClO_3=2KCl + 3O_2$
7. $2Na+2H_2O = 2NaOH + H_2$