Question

practice: balancing equations #1
show all work on a separate sheet of paper. place coefficients (not exponents) in the blanks provided. you can have coefficients of 1 if needed.

1. 4 h₂ + 2 o₂ → 2 h₂o
2. 1 h₃po₄ + 3 koh → 1 k₃po₄ + 3 h₂o
3. 6 k + 1 b₂o₃ → 3 k₂o + 2 b
4. 3 hcl + 1 naoh → 1 nacl + 1 h₂o
5. 10 na + 2 nano₃ → 6 na₂o + 1 n₂
6. c + s₈ → __ cs₂
7. na + o₂ → __ na₂o₂
8. n₂ + o₂ → __ n₂o₅
9. h₃po₄ + mg(oh)₂ → mg₃(po₄)₂ + h₂o
10. naoh + h₂co₃ → na₂co₃ + h₂o
11. koh + hbr → kbr + h₂o
12. h₂ + o₂ → __ h₂o₂
13. na + o₂ → __ na₂o
14. al(oh)₃ + h₂co₃ → al₂(co₃)₃ + h₂o
15. al + s₈ → __ al₂s₃
16. ca + n₂ → __ ca₃n₂
17. mg + cl₂ → __ mgcl₂
18. rb + rbno₃ → rb₂o + n₂
19. c₆h₆ + o₂ → co₂ + h₂o
20. n₂ + h₂ → __ nh₃

Explanation:

Step1: Balance equation 6

For $C + S_2
ightarrow CS_2$, the number of atoms of each element is already the same on both sides. So the coefficients are 1, 1, 1.

Step2: Balance equation 7

For $Na+O_2
ightarrow Na_2O_2$, to balance sodium and oxygen, we need 2 Na on the left - hand side. So the coefficients are 2, 1, 1.

Step3: Balance equation 8

For $N_2 + O_2
ightarrow N_2O_5$, we need 5 oxygen atoms on the right - hand side. Multiply $O_2$ by $\frac{5}{2}$ and $N_2O_5$ by 1, $N_2$ by 1. To get whole - number coefficients, multiply all by 2. So the coefficients are 2, 5, 2.

Step4: Balance equation 9

For $H_3PO_4+Mg(OH)_2
ightarrow Mg_3(PO_4)_2 + H_2O$, balance magnesium first. We need 3 $Mg(OH)_2$. Then balance phosphorus, which is already balanced. For hydrogen and oxygen, we need 2 $H_3PO_4$ and 6 $H_2O$. So the coefficients are 2, 3, 1, 6.

Step5: Balance equation 10

For $NaOH + H_2CO_3
ightarrow Na_2CO_3+H_2O$, balance sodium first. We need 2 $NaOH$. Then the equation is balanced. So the coefficients are 2, 1, 1, 1.

Step6: Balance equation 11

For $KOH + HBr
ightarrow KBr + H_2O$, the equation is already balanced with coefficients 1, 1, 1, 1.

Step7: Balance equation 12

For $H_2+O_2
ightarrow H_2O_2$, the equation is balanced with coefficients 1, 1, 1.

Step8: Balance equation 13

For $Na + O_2
ightarrow Na_2O$, we need 4 Na on the left - hand side to balance sodium and oxygen. So the coefficients are 4, 1, 2.

Step9: Balance equation 14

For $Al(OH)_3+H_2CO_3
ightarrow Al_2(CO_3)_3 + H_2O$, balance aluminum first. We need 2 $Al(OH)_3$. Then balance carbonate and hydrogen - oxygen. We need 3 $H_2CO_3$ and 6 $H_2O$. So the coefficients are 2, 3, 1, 6.

Step10: Balance equation 15

For $Al+S_8
ightarrow Al_2S_3$, balance sulfur first. We need 8 $Al_2S_3$ and 3 $S_8$. Then balance aluminum, we need 16 $Al$. So the coefficients are 16, 3, 8.

Step11: Balance equation 16

For $Ca + N_2
ightarrow Ca_3N_2$, we need 3 Ca on the left - hand side. So the coefficients are 3, 1, 1.

Step12: Balance equation 17

For $Mg+Cl_2
ightarrow MgCl_2$, the equation is balanced with coefficients 1, 1, 1.

Step13: Balance equation 18

For $Rb+RbNO_3
ightarrow Rb_2O + N_2$, balance nitrogen first. We need 2 $RbNO_3$. Then balance oxygen and rubidium. We need 10 $Rb$, 2 $RbNO_3$, 5 $Rb_2O$ and 1 $N_2$. So the coefficients are 10, 2, 5, 1.

Step14: Balance equation 19

For $C_6H_6+O_2
ightarrow CO_2 + H_2O$, balance carbon first. We need 6 $CO_2$. Then balance hydrogen, we need 3 $H_2O$. Then balance oxygen, we need $\frac{15}{2}O_2$. Multiply all by 2 to get whole - number coefficients. So the coefficients are 2, 15, 12, 6.

Step15: Balance equation 20

For $N_2+H_2
ightarrow NH_3$, we need 2 $NH_3$ to balance nitrogen and 3 $H_2$ to balance hydrogen. So the coefficients are 1, 3, 2.

Answer:

1. 1, 1, 1
2. 2, 1, 1
3. 2, 5, 2
4. 2, 3, 1, 6
5. 2, 1, 1, 1
6. 1, 1, 1, 1
7. 1, 1, 1
8. 4, 1, 2
9. 2, 3, 1, 6
10. 16, 3, 8
11. 3, 1, 1
12. 1, 1, 1
13. 10, 2, 5, 1
14. 2, 15, 12, 6
15. 1, 3, 2