Table of contents

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