Cell Diagram [ENDORSED]

[Mike Matthews 1D]

How does one determine which elements and or compounds are reactants and which are products from looking at a cell diagram? In other words, if you looked at the left (anode) side of a cell diagram, how do you know which are reactants and which are products in the oxidation half reaction?

[Chem_Mod]

You can determine products and reactants based on what type of reaction occurs at the anode and what occurs at the cathode. Remember that oxidation, in which an electron and ion are products, is always at the anode. Reduction, in which an electron and ion are the reactants, is always at the cathode.

A useful mnemonic is REDCAT and ANOX!

[Ozhen Atoyan 1F]

When you look at the cell diagram whichever comes first from the left is the reactant and as you go to the right they are the products. If you see Pt(s) or C(graphite) those are not a part of the reaction.

[Ryan Neis 2L]

Visually, at the cathode, since the metal ions are being reduced, there will be an increase in the solid metal, that's how you know that the solid metal at the cathode is a product, and the metal ions are the reactants. In the anode, the opposite process occurs making the metal ions at the anode the products and the solid metal the reactant.

[Curtis Tam 1J]

Sometimes the only species are available as ions and are separated by commas on one side of the cell diagram. Does it need to be in any particular order? I feel like there are some inconsistencies in the book problems in regards to how they order the ions

[Chem_Mod]

For cell diagram, within each half part, electrode and solids are written far away from the salt bridge, followed by liquid, gas and aqueous solution. Within each phase, orders are not strictly defined, but people tend to put in the order of reactant to product.