Question

zn + hcl → zncl₂ + h₂
secl₆ + o₂ → seo₂ + cl₂
fe + h₂so₄ → fe₂(so₄)₃ + h₂
agi + na₂s → ag₂s + nai
nabr + h₃po₄ → na₃po₄ + hbr
ca(oh)₂ + al₂(so₄)₃ → caso₄ + al(oh)₃
me + fe₂o₃ → fe + mgo
nh₃ + i₂ → ni₃ + h₂
secl₆ + o₂ → seo₂ + cl₂

Explanation:

Step1: Balance Zn + HCl reaction

Balance Zn, Cl, H atoms.
$\boldsymbol{1Zn + 2HCl
ightarrow 1ZnCl_2 + 1H_2}$

Step2: Balance SeCl₆ + O₂ reaction

Balance Se, Cl, O atoms.
$\boldsymbol{1SeCl_6 + 2O_2
ightarrow 1SeO_2 + 3Cl_2}$

Step3: Balance Fe + H₂SO₄ reaction

Balance Fe, S, O, H atoms.
$\boldsymbol{2Fe + 3H_2SO_4
ightarrow 1Fe_2(SO_4)_3 + 3H_2}$

Step4: Balance AgI + Na₂S reaction

Balance Ag, S, Na, I atoms.
$\boldsymbol{2AgI + 1Na_2S
ightarrow 1Ag_2S + 2NaI}$

Step5: Balance NaBr + H₃PO₄ reaction

Balance Na, P, Br, H atoms.
$\boldsymbol{3NaBr + 1H_3PO_4
ightarrow 1Na_3PO_4 + 3HBr}$

Step6: Balance Ca(OH)₂ + Al₂(SO₄)₃ reaction

Balance Ca, SO₄, Al, OH atoms.
$\boldsymbol{3Ca(OH)_2 + 1Al_2(SO_4)_3
ightarrow 3CaSO_4 + 2Al(OH)_3}$

Step7: Balance Mg + Fe₂O₃ reaction

Balance Mg, Fe, O atoms.
$\boldsymbol{3Mg + 1Fe_2O_3
ightarrow 2Fe + 3MgO}$

Step8: Balance NH₃ + I₂ reaction

Balance N, H, I atoms.
$\boldsymbol{2NH_3 + 3I_2
ightarrow 1N_2I_6 + 3H_2}$

Step9: Balance SeCl₆ + O₂ (duplicate) reaction

Balance Se, Cl, O atoms.
$\boldsymbol{1SeCl_6 + 2O_2
ightarrow 1SeO_2 + 3Cl_2}$

Answer:

1. $\boldsymbol{1Zn + 2HCl

ightarrow 1ZnCl_2 + 1H_2}$

1. $\boldsymbol{1SeCl_6 + 2O_2

ightarrow 1SeO_2 + 3Cl_2}$

1. $\boldsymbol{2Fe + 3H_2SO_4

ightarrow 1Fe_2(SO_4)_3 + 3H_2}$

1. $\boldsymbol{2AgI + 1Na_2S

ightarrow 1Ag_2S + 2NaI}$

1. $\boldsymbol{3NaBr + 1H_3PO_4

ightarrow 1Na_3PO_4 + 3HBr}$

1. $\boldsymbol{3Ca(OH)_2 + 1Al_2(SO_4)_3

ightarrow 3CaSO_4 + 2Al(OH)_3}$

1. $\boldsymbol{3Mg + 1Fe_2O_3

ightarrow 2Fe + 3MgO}$

1. $\boldsymbol{2NH_3 + 3I_2

ightarrow 1N_2I_6 + 3H_2}$

1. $\boldsymbol{1SeCl_6 + 2O_2

ightarrow 1SeO_2 + 3Cl_2}$