Question

When calcium and chlorine react to form calcium chloride, which substance is reduced? *

Answer 1

Answer:-

When the reaction takes place Ca is reduced or is an oxidizing agent.

Reaction:

Ca + 2Cl =CaCl2

Note: There is a +2 charge on Ca(Calcium) and -1 charge on each Cl-atom(Chlorine atom) hence the charges are cancelled. Therefore, the total charge on the whole compound is zero.

Explanation:-

• Reduction: gain of electron/electrons

gain of hydrogen

loss of oxygen

Oxidation: gain of oxygen

loss of hydrogen

loss of electron/electrons.

• Oxidizing agent/reduced

Reducing agent/oxidized

• The molecule that is oxidized loses an electron and the molecule that is reduced gains the electron that was lost by the oxidized molecule.

Answer 2

Answer:

$\boxed{\text{Chlorine}}$

Explanation:

We must use oxidation numbers to decide which substance is reduced.  

$\rm \stackrel{\hbox{0}}{\hbox{Ca}} + \stackrel{\hbox{0}}{\hbox{ Cl}_{2} }\longrightarrow \stackrel{\hbox{+2}}{\hbox{Ca }}\stackrel{\hbox{-1}}{\hbox{Cl}_{2}}$

The oxidation number of Ca increases from 0 in Ca to +2 in CaCl₂.

The oxidation number of Cl decreases from 0 in Cl₂ to -1 in CaCl₂.

$\text{A decrease in oxidation number is reduction, so } \boxed{\textbf{Cl _{2} is the substance reduced.}}$