Question

In the equation PbO2 + 4HCl → 2H2O + PbCl2 + Cl2, how many electrons are transferred?

Answer 1

redox equations have a lot of steps but I'll try and break them down one by one

1. balance all the atoms except oxygen and hydrogen (to save some time, your equation is already balanced this way, so move on to step 2)

2. assign oxidation numbers for every atom in each compound (if you need me to explain this I am happy to). then determine which compound is being oxidized and which is being reduced.

Answer 2

\(\color{#0cbb34}{\text{Originally Posted by}}\) @Michael
Check that that the equation is balanced for charge and mass - it is.
Assign the oxidation number of each element:

\[\rm\stackrel{\color{red}{+4}}{Pb}\stackrel{-2}O_2 + 4\stackrel{+1}{H}\stackrel{\color{green}{-1}}{Cl}\,\,\,\rightarrow\,\,\,\stackrel{\color{red}{+2}}{Pb}\stackrel{-1}{Cl}_2\,\,\,+\,\,\,\stackrel{\color{green}0}{Cl}_2\,\,\,\,+\,\,\,2\stackrel{+1}{H}_2\stackrel{-2}{O}\]

You can see that Pb has gone from +4 to +2 so it has been reduced.

Two Cl have gone from -1 to zero so have been oxidised.

You can see that 2 electrons must have been transferred to effect this change.
\(\color{#0cbb34}{\text{End of Quote}}\)