Question

use with textbook pages 202 - 211.
word equations
write the skeleton equation for each of the following reactions. then balance each of the following chemical equations.

1. hydrogen + oxygen → water
2. iron(iii) oxide + hydrogen → water + iron
3. sodium + water → sodium hydroxide + hydrogen
4. calcium carbide + oxygen → calcium + carbon dioxide
5. potassium iodide + chlorine → potassium chloride + iodine
6. chromium + tin(iv) chloride → chromium(iii) chloride + tin
7. magnesium + copper(ii) sulphate → magnesium sulphate + copper
8. zinc sulphate + strontium chloride → zinc chloride + strontium sulphate
9. ammonium chloride + lead(iii) nitrate → ammonium nitrate + lead(iii) chloride
10. iron(iii) nitrate + magnesium sulphide → iron(iii) sulphide + magnesium nitrate
11. aluminum chloride + sodium carbonate → aluminum carbonate + sodium chloride
12. sodium phosphate + calcium hydroxide → sodium hydroxide + calcium phosphate

Explanation:

Step1: Write the skeleton equation

For each reaction, write the chemical formulas of the reactants and products. For example, for "hydrogen + oxygen → water", hydrogen is \(H_2\), oxygen is \(O_2\), and water is \(H_2O\). So the skeleton equation is \(H_2+O_2
ightarrow H_2O\).

Step2: Balance the equation

Use the method of balancing atoms. For \(H_2+O_2
ightarrow H_2O\):

• Count the number of each atom on both sides. On the left, \(H = 2\), \(O=2\); on the right, \(H = 2\), \(O = 1\).
• Multiply \(H_2O\) by 2 to get \(H_2+O_2

ightarrow 2H_2O\). Now \(H = 2\) (left) and \(H=4\) (right), \(O = 2\) (left) and \(O = 2\) (right).

• Multiply \(H_2\) by 2. The balanced equation is \(2H_2+O_2 = 2H_2O\).

Similarly for other reactions:

1. Skeleton equation: \(H_2+O_2

ightarrow H_2O\)

• Balanced equation: \(2H_2+O_2 = 2H_2O\)

1. Skeleton equation: \(Fe_2O_3+H_2

ightarrow H_2O+Fe\)

• Balanced equation: \(Fe_2O_3 + 3H_2=3H_2O + 2Fe\)

1. Skeleton equation: \(Na+H_2O

ightarrow NaOH+H_2\)

• Balanced equation: \(2Na+2H_2O = 2NaOH+H_2\)

1. Skeleton equation: \(CaC_2+O_2

ightarrow Ca+CO_2\)

• Balanced equation: \(CaC_2+2O_2 = Ca + 2CO_2\)

1. Skeleton equation: \(KI+Cl_2

ightarrow KCl+I_2\)

• Balanced equation: \(2KI+Cl_2 = 2KCl+I_2\)

1. Skeleton equation: \(Cr+SnCl_4

ightarrow CrCl_3+Sn\)

• Balanced equation: \(4Cr + 3SnCl_4=4CrCl_3+3Sn\)

1. Skeleton equation: \(Mg+CuSO_4

ightarrow MgSO_4+Cu\)

• Balanced equation: \(Mg+CuSO_4 = MgSO_4+Cu\) (already balanced)

1. Skeleton equation: \(ZnSO_4+SrCl_2

ightarrow ZnCl_2+SrSO_4\)

• Balanced equation: \(ZnSO_4+SrCl_2 = ZnCl_2+SrSO_4\) (already balanced)

1. Skeleton equation: \(NH_4Cl+Pb(NO_3)_2

ightarrow NH_4NO_3+PbCl_2\)

• Balanced equation: \(2NH_4Cl+Pb(NO_3)_2 = 2NH_4NO_3+PbCl_2\)

1. Skeleton equation: \(Fe(NO_3)_3+MgS

ightarrow Fe_2S_3+Mg(NO_3)_2\)

• Balanced equation: \(2Fe(NO_3)_3+3MgS = Fe_2S_3+3Mg(NO_3)_2\)

1. Skeleton equation: \(AlCl_3+Na_2CO_3

ightarrow Al_2(CO_3)_3+NaCl\)

• Balanced equation: \(2AlCl_3+3Na_2CO_3 = Al_2(CO_3)_3+6NaCl\)

1. Skeleton equation: \(Na_3PO_4+Ca(OH)_2

ightarrow NaOH+Ca_3(PO_4)_2\)

• Balanced equation: \(2Na_3PO_4+3Ca(OH)_2 = 6NaOH+Ca_3(PO_4)_2\)

Answer:

1. Skeleton: \(H_2+O_2

ightarrow H_2O\); Balanced: \(2H_2+O_2 = 2H_2O\)

1. Skeleton: \(Fe_2O_3+H_2

ightarrow H_2O+Fe\); Balanced: \(Fe_2O_3 + 3H_2=3H_2O + 2Fe\)

1. Skeleton: \(Na+H_2O

ightarrow NaOH+H_2\); Balanced: \(2Na+2H_2O = 2NaOH+H_2\)

1. Skeleton: \(CaC_2+O_2

ightarrow Ca+CO_2\); Balanced: \(CaC_2+2O_2 = Ca + 2CO_2\)

1. Skeleton: \(KI+Cl_2

ightarrow KCl+I_2\); Balanced: \(2KI+Cl_2 = 2KCl+I_2\)

1. Skeleton: \(Cr+SnCl_4

ightarrow CrCl_3+Sn\); Balanced: \(4Cr + 3SnCl_4=4CrCl_3+3Sn\)

1. Skeleton: \(Mg+CuSO_4

ightarrow MgSO_4+Cu\); Balanced: \(Mg+CuSO_4 = MgSO_4+Cu\)

1. Skeleton: \(ZnSO_4+SrCl_2

ightarrow ZnCl_2+SrSO_4\); Balanced: \(ZnSO_4+SrCl_2 = ZnCl_2+SrSO_4\)

1. Skeleton: \(NH_4Cl+Pb(NO_3)_2

ightarrow NH_4NO_3+PbCl_2\); Balanced: \(2NH_4Cl+Pb(NO_3)_2 = 2NH_4NO_3+PbCl_2\)

1. Skeleton: \(Fe(NO_3)_3+MgS

ightarrow Fe_2S_3+Mg(NO_3)_2\); Balanced: \(2Fe(NO_3)_3+3MgS = Fe_2S_3+3Mg(NO_3)_2\)

1. Skeleton: \(AlCl_3+Na_2CO_3

ightarrow Al_2(CO_3)_3+NaCl\); Balanced: \(2AlCl_3+3Na_2CO_3 = Al_2(CO_3)_3+6NaCl\)

1. Skeleton: \(Na_3PO_4+Ca(OH)_2

ightarrow NaOH+Ca_3(PO_4)_2\); Balanced: \(2Na_3PO_4+3Ca(OH)_2 = 6NaOH+Ca_3(PO_4)_2\)