Following oxidation-reduction reaction by using the oxidation state method
a) O2+H2O+Pb=Pb(OH)2
basic solution.
Pb + 2OH^- ==> Pb(OH)2 + 2e
O2 + 4e + 2H2O ==> 2OH^- + 2OH^-
Multiply equation 1 by 2 and equation 2 by 1 and add. Cancel any ions/molecules common to both sides.
To determine the oxidation state of each element in the reaction, we can follow these steps:
1. Write the equation: O2 + H2O + Pb = Pb(OH)2
2. Identify the elements and assign oxidation states (OS) to each element. The oxidation state is a number that represents the charge an atom would have if electrons were transferred completely.
O2: Oxygen typically has an oxidation state of -2. In this case, since it is diatomic (O2), each oxygen atom has an OS of -1.
H2O: Hydrogen generally has an OS of +1, and oxygen has an OS of -2. Since the overall charge of a water molecule is neutral, the oxidation state of oxygen is -2 and hydrogen is +1.
Pb: Since we know the remaining oxidation states, we can calculate the oxidation state for lead. Oxygen has an OS of -2, and there are two OH groups, each with an overall charge of -1. Therefore, the oxidation state of lead must be +2 to balance the charges.
After assigning the oxidation states, we have:
Oxygen (O2): -1
Hydrogen (H2O): +1
Lead (Pb): +2
3. Determine the change in oxidation state for each element. To do this, we compare the oxidation states of each element on both sides of the equation.
Oxygen: The OS of oxygen changes from 0 to -1 on the left side because it is combined with another oxygen atom to form O2. On the right side, each oxygen is part of a hydroxide ion, so the OS is -1.
Hydrogen: The OS of hydrogen remains the same at +1 on both sides of the equation.
Lead: The OS of lead changes from 0 to +2 on the left side because it is combined with hydroxide ions.
4. Balance the equation by adjusting the coefficients for each species so that the total change in oxidation state is zero.
O2 + 2H2O + Pb = Pb(OH)2
This balanced equation represents the oxidation-reduction reaction using the oxidation state method.