Question

1. tell type of eqn (s=synthesis, d=decomposition, sr=single replacement, dr=double replacement, c=combustion)
2. balance each of the following equations. show work!

remember — list the atoms, count, and solve!

1. \\(\ce{h2 + o2 -> h2o (5) 2) h2o2 -> h2o + o2 ( ) 3) na + o2 -> na2o ( )}
2. \\(\ce{n2 + h2 -> nh3 ( ) 5) p4 + o2 -> p4o6 ( ) 6) c + h2 -> ch4 ( )}
3. \\(\ce{al2o3 -> al + o2 ( )}
4. \\(\ce{fe + h2o -> fe3o4 + h2 ( )}
5. \\(\ce{c3h8 + o2 -> co2 + h2o ( ) 10) na2so4 + cacl2 -> caso4 + nacl ( )}

Explanation:

Step1: Balance equation 1 (Synthesis)

Count H: 2 on left, 2 on right; Count O: 2 on left, 1 on right. Multiply $\text{H}_2\text{O}$ by 2, then $\text{H}_2$ by 2.

$$2\text{H}_2 + \text{O}_2 ightarrow 2\text{H}_2\text{O}$$

Reaction type: Synthesis (S)

Step2: Balance equation 2 (Decomposition)

Count H: 2 on left, 2 on right; Count O: 2 on left, 1+2=3 on right. Multiply $\text{H}_2\text{O}_2$ by 2, $\text{H}_2\text{O}$ by 2.

$$2\text{H}_2\text{O}_2 ightarrow 2\text{H}_2\text{O} + \text{O}_2$$

Reaction type: Decomposition (D)

Step3: Balance equation 3 (Synthesis)

Count Na: 1 on left, 2 on right; Count O: 2 on left, 1 on right. Multiply $\text{Na}$ by 2, $\text{Na}_2\text{O}$ by 2, then $\text{O}_2$ by 1.

$$4\text{Na} + \text{O}_2 ightarrow 2\text{Na}_2\text{O}$$

Reaction type: Synthesis (S)

Step4: Balance equation 4 (Synthesis)

Count N: 2 on left, 1 on right; Count H: 2 on left, 3 on right. Multiply $\text{NH}_3$ by 2, $\text{H}_2$ by 3.

$$\text{N}_2 + 3\text{H}_2 ightarrow 2\text{NH}_3$$

Reaction type: Synthesis (S)

Step5: Balance equation 5 (Synthesis)

Count P: 4 on left, 4 on right; Count O: 2 on left, 6 on right. Multiply $\text{O}_2$ by 3.

$$\text{P}_4 + 3\text{O}_2 ightarrow \text{P}_4\text{O}_6$$

Reaction type: Synthesis (S)

Step6: Balance equation 6 (Synthesis)

Count C:1 on left,1 on right; Count H:2 on left,4 on right. Multiply $\text{H}_2$ by 2.

$$\text{C} + 2\text{H}_2 ightarrow \text{CH}_4$$

Reaction type: Synthesis (S)

Step7: Balance equation 7 (Decomposition)

Count Al:2 on left,1 on right; Count O:3 on left,2 on right. Multiply $\text{Al}$ by 2, $\text{O}_2$ by $\frac{3}{2}$, then multiply all by 2.

$$2\text{Al}_2\text{O}_3 ightarrow 4\text{Al} + 3\text{O}_2$$

Reaction type: Decomposition (D)

Step8: Balance equation 8 (Single Replacement)

Count Fe:1 on left,3 on right; Count H:2 on left,2 on right; Count O:1 on left,4 on right. Multiply $\text{H}_2\text{O}$ by 4, $\text{H}_2$ by 4, $\text{Fe}$ by 3.

$$3\text{Fe} + 4\text{H}_2\text{O} ightarrow \text{Fe}_3\text{O}_4 + 4\text{H}_2$$

Reaction type: Single Replacement (SR)

Step9: Balance equation 9 (Combustion)

Count C:3 on left,1 on right; Count H:8 on left,2 on right; Count O:2 on left,2+1=3 on right. Multiply $\text{CO}_2$ by 3, $\text{H}_2\text{O}$ by 4, $\text{O}_2$ by 5.

$$\text{C}_3\text{H}_8 + 5\text{O}_2 ightarrow 3\text{CO}_2 + 4\text{H}_2\text{O}$$

Reaction type: Combustion (C)

Step10: Balance equation 10 (Double Replacement)

Count Na:2 on left,1 on right; Count S:1 on left,1 on right; Count O:4 on left,4 on right; Count Ca:1 on left,1 on right; Count Cl:2 on left,1 on right. Multiply $\text{NaCl}$ by 2.

$$\text{Na}_2\text{SO}_4 + \text{CaCl}_2 ightarrow \text{CaSO}_4 + 2\text{NaCl}$$

Reaction type: Double Replacement (DR)

Answer:

1. $2\text{H}_2 + \text{O}_2

ightarrow 2\text{H}_2\text{O}$ (S)

1. $2\text{H}_2\text{O}_2

ightarrow 2\text{H}_2\text{O} + \text{O}_2$ (D)

1. $4\text{Na} + \text{O}_2

ightarrow 2\text{Na}_2\text{O}$ (S)

1. $\text{N}_2 + 3\text{H}_2

ightarrow 2\text{NH}_3$ (S)

1. $\text{P}_4 + 3\text{O}_2

ightarrow \text{P}_4\text{O}_6$ (S)

1. $\text{C} + 2\text{H}_2

ightarrow \text{CH}_4$ (S)

1. $2\text{Al}_2\text{O}_3

ightarrow 4\text{Al} + 3\text{O}_2$ (D)

1. $3\text{Fe} + 4\text{H}_2\text{O}

ightarrow \text{Fe}_3\text{O}_4 + 4\text{H}_2$ (SR)

1. $\text{C}_3\text{H}_8 + 5\text{O}_2

ightarrow 3\text{CO}_2 + 4\text{H}_2\text{O}$ (C)

1. $\text{Na}_2\text{SO}_4 + \text{CaCl}_2

ightarrow \text{CaSO}_4 + 2\text{NaCl}$ (DR)