Question

1. balance and label reaction types

$\ce{c3h8}$ + $\ce{o2}$ $\
ightarrow$ __ $\ce{co2}$ + __$\ce{h2o}$

$\ce{n2}$ + $\ce{h2}$ $\
ightarrow$ __$\ce{nh3}$

$\ce{na3(po4)}$ + $\ce{k(oh)}$ $\
ightarrow$ __ $\ce{na(oh)}$ + __$\ce{k3(po4)}$

$\ce{mg}$ + $\ce{ag(no3)}$ $\
ightarrow$ __ $\ce{mg(no3)2}$ + __ $\ce{ag}$

Explanation:

Step1: Balance \( \boldsymbol{\ce{C3H8 + O2 -> CO2 + H2O}} \)

• Start with \( \ce{C3H8} \): 3 C, 8 H. So \( \ce{CO2} \) needs 3 (for C), \( \ce{H2O} \) needs 4 (for H: \( 8/2 = 4 \)).
• Now O: \( \ce{CO2} \) has \( 3\times2 = 6 \), \( \ce{H2O} \) has \( 4\times1 = 4 \), total O on right: \( 6 + 4 = 10 \). So \( \ce{O2} \) needs \( 10/2 = 5 \).
• Balanced: \( \boldsymbol{1}\ce{C3H8} + \boldsymbol{5}\ce{O2}

ightarrow \boldsymbol{3}\ce{CO2} + \boldsymbol{4}\ce{H2O} \) (Combustion reaction)

Step2: Balance \( \boldsymbol{\ce{N2 + H2 -> NH3}} \)

• N: 2 on left, 1 on right. So \( \ce{NH3} \) needs 2. Then H: \( 2\times3 = 6 \), so \( \ce{H2} \) needs \( 6/2 = 3 \).
• Balanced: \( \boldsymbol{1}\ce{N2} + \boldsymbol{3}\ce{H2}

ightarrow \boldsymbol{2}\ce{NH3} \) (Synthesis reaction)

Step3: Balance \( \boldsymbol{\ce{Na3(PO4) + K(OH) -> Na(OH) + K3(PO4)}} \)

• \( \ce{Na3(PO4)} \): 3 Na, so \( \ce{Na(OH)} \) needs 3. \( \ce{K3(PO4)} \): 3 K, so \( \ce{K(OH)} \) needs 3.
• Balanced: \( \boldsymbol{1}\ce{Na3(PO4)} + \boldsymbol{3}\ce{K(OH)}

ightarrow \boldsymbol{3}\ce{Na(OH)} + \boldsymbol{1}\ce{K3(PO4)} \) (Double - displacement reaction)

Step4: Balance \( \boldsymbol{\ce{Mg + Ag(NO3) -> Mg(NO3)2 + Ag}} \)

• \( \ce{Mg(NO3)2} \): 2 \( \ce{NO3^-} \), so \( \ce{Ag(NO3)} \) needs 2. Then Ag: 2 on left, so Ag on right needs 2.
• Balanced: \( \boldsymbol{1}\ce{Mg} + \boldsymbol{2}\ce{Ag(NO3)}

ightarrow \boldsymbol{1}\ce{Mg(NO3)2} + \boldsymbol{2}\ce{Ag} \) (Single - displacement reaction)

Answer:

1. \( 1\ce{C3H8} + 5\ce{O2}

ightarrow 3\ce{CO2} + 4\ce{H2O} \) (Combustion)

1. \( 1\ce{N2} + 3\ce{H2}

ightarrow 2\ce{NH3} \) (Synthesis)

1. \( 1\ce{Na3(PO4)} + 3\ce{K(OH)}

ightarrow 3\ce{Na(OH)} + 1\ce{K3(PO4)} \) (Double - displacement)

1. \( 1\ce{Mg} + 2\ce{Ag(NO3)}

ightarrow 1\ce{Mg(NO3)2} + 2\ce{Ag} \) (Single - displacement)