This is an oxidation-reduction (redox) reaction:
2 HI + 2e- → 2 H0 (reduction)
Ca0 - 2 e- → CaII (oxidation)
H2O is an oxidizing agent, Ca is a reducing agent.
Word equation
calcium + water → calcium hydroxide + hydrogen
Input interpretation
Ca + H2O → Ca(OH)2 + H2
Calcium water calcium hydroxide hydrogen
Balanced equation
Balance the chemical equation algebraically:
Ca + H2O → Ca(OH)2 + H2
Add stoichiometric coefficients, c, to the reactants and products:
Ca + H2O → Ca(OH)2 + H2
Set the number of atoms in the reactants equal to the number of atoms in the products for Ca, H and O:
Ca: c1 = c3
H: 2c2 = 2c3 + 2c4
O: c2 = 2c3
Since the coefficients are relative quantities and underdetermined, choose a coefficient to set arbitrarily. To keep the coefficients small, the arbitrary value is ordinarily one. For instance, set c1 = 1 and solve the system of equations for the remaining coefficients:
c1=1
c2=2
c3=1
c4=1
Substitute the coefficients into the chemical reaction to obtain the balanced
equation:
Answer:
Ca + H2O → Ca(OH)2 + H2
