Write the reactants and products of the reaction between zinc and oxygen. Include the half-reactions. What type of reaction is this?
I know the reaction is 2Zn + O2 -> 2ZnO
I am not really sure where to go from here.
Your full equation is ok.
The half equations are
Zn ==> Zn^2+ + 2electrons
O2 + 4 electrons ==> 2O^2-
For the full equation you multiply equation 1 by 2 and add to equation 2.
To determine the half-reactions of a reaction, you need to examine the oxidation states and balance the charges on both sides. Let's break down the reaction and determine the half-reactions:
The reaction is: 2Zn + O2 -> 2ZnO
First, let's assign oxidation states to each element.
Zinc (Zn) is a metal and has an oxidation state of 0 since it is the element by itself in its standard state.
Oxygen (O2) has an oxidation state of 0 since it is the element by itself.
In zinc oxide (ZnO), each oxygen atom has an oxidation state of -2. Since there are two oxide (O) atoms in ZnO, the overall oxidation state for oxygen is -4. To balance the charge, the oxidation state of zinc (Zn) in ZnO is +2.
Now, let's write the half-reactions:
1) Oxidation half-reaction:
Zinc (Zn) is oxidized from an oxidation state of 0 to +2. Therefore, the half-reaction for the oxidation of zinc is: Zn -> Zn2+ + 2e-
2) Reduction half-reaction:
Oxygen (O2) is reduced from an oxidation state of 0 to -2. Therefore, the half-reaction for the reduction of oxygen is: O2 + 4e- -> 2O2-
Now, let's combine the two half-reactions to balance the charges:
2Zn + O2 + 4e- -> 2Zn2+ + 2O2-
Finally, we can cancel out the electrons (e-) that appear on both sides of the equation to get the balanced overall reaction:
2Zn + O2 -> 2Zn2+ + 2O2-
The overall reaction is a combination reaction, specifically a synthesis reaction, where two substances (Zn and O2) combine to form a single compound (ZnO).