Chem幾條 balancing equation

1. 2C2H­6 + 7O2 → 4CO2 + 6H2O

Steps:
(1) Write all reactants and products as chemical formulae:
C2H­6 + O2 → CO2 + H2O
(2) Make 2 C on both sides:
1C2H­6 + O2 → 2CO2 + H2O
(3) Make 6 H on both sides:
1C2H­6 + O2 → 2CO2 + 3H2O
(4) Make 7 O on both sides:
1C2H­6 + (7/2)O2 → 2CO2 + 3H2O
(5) Multiply each side by 2:
2C2H­6 + 7O2 → 4CO2 + 6H2O


2. CaO + H2O → Ca(OH)2

Steps:
(1) Write all reactants and products as chemical formulae:
CaO + H2O → Ca(OH)2
(2) Make 2 Ca on both sides:
1CaO + H2O → 1Ca(OH)2
(3) Make 2 H on both sides.
1CaO + 1H2O → 1Ca(OH)2


3. 2Pb(NO3)2 → 2PbO + 4NO2 + O2

Steps:
(1) Write all reactants and products as chemical formulae:
Pb(NO3)2 → PbO + NO2 + O2
(2) Make 1 Pb on both sides.
1Pb(NO3)2 → 1PbO + NO2 + O2
(3) Make 2 N on both sides.
1Pb(NO3)2 → 1PbO + 2NO2 + O2
(4) Make 6 O on both sides.
1Pb(NO3)2 → 1PbO + 2NO2 + (1/2)O2
(5) Multiply each side by 2:
2Pb(NO3)2 → 2PbO + 4NO2 + 1O2


4. 2Na + 2H2O → 2NaOH + H2

(1) Make 1 Na on both sides.
1Na + H2O → 1NaOH + H2
(2) Make 1 O on both sides.
1Na + 1H2O → 1NaOH + H2
(3) Make 2 H on both sides.
1Na + 1H2O → 1NaOH + (1/2)H2
(4) Multiply each side by 2:
2Na + 2H2O → 2NaOH + 1H2


5. 2KClO­3 → 2KCl + 3O2

(1) Make 6 O on both sides:
2KClO­3 → KCl + 3O2
(2) Make 2 K on both sides.
2KClO­3 → 2KCl + 3O2


6. 2NaHCO3 + H2SO4 → Na2SO4 + 2H2O + 2CO2

Steps:
(1) Write all reactants and products as chemical formulae:
NaHCO3 + H2SO4 → Na2SO4 + H2O + CO2
(2) Make 2 Na on both sides:
2NaHCO3 + H2SO4 → 1Na2SO4 + H2O + CO2
(3) Make 1 S on both sides:
2NaHCO3 + 1H2SO4 → 1Na2SO4 + H2O + CO2
(4) Make 4 H on both sides:
2NaHCO3 + 1H2SO4 → 1Na2SO4 + 2H2O + CO2
(5) Make 2 C on both sides:
2NaHCO3 + 1H2SO4 → 1Na2SO4 + 2H2O + 2CO2