This is an oxidation-reduction (redox) reaction:
2 HI + 2 e- → 2 H0 (reduction)
Ca0 - 2 e- → CaII (oxidation)
HClO4 is an oxidizing agent, Ca is a reducing agent.
Word equation
calcium + perchloric acid → calcium perchlorate + hydrogen
Input interpretation
Ca + HClO4 → Ca(ClO4)2 + H2
Calcium perchloric acid calcium perchlorate hydrogen
Balanced equation
Balance the chemical equation algebraically:
Ca + HClO4 → Ca(ClO4)2 + H2
Add stoichiometric coefficients, c, to the reactants and products:
c1Ca + c2HClO4 → c3 Ca(ClO4)2 + c4 H2
Set the number of atoms in the reactants equal to the number of atoms in the products for Ca, Cl, H and O:
Ca: c1 = c3
Cl: c2 = 2c3
H: c2 = 2c4
O: 4c2 = 8c3
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 + HClO4 → Ca(ClO4)2 + H2
Word equation
calcium + perchloric acid → calcium perchlorate + hydrogen
