Chemistry 12 help, ++ MAD KARMA

popNfresh44

popNfresh44

Active member
so i'm trying to do questions for my chem lab, and its hard to do them when i dont know what is actually happening.

its equilibrium.

(Fe3+) + (SCN-) FeSCN2+

i need to know which way the equilibrium shifts and why when these stresses are added:

1. Fe(NO3)3

2. KSCN

3. NaOH
 
I would think in the first two, the reaction would shift to the right (toward the product) because the original compounds would disassociate, producing more reactants (Fe in the first and SCN- in the second) which would cause more products to spontaneously form.

I don't know about the last one, though - either it would have no effect, or it would shift it to the left by increasing synthesis in alternate pathways (for example, forming NaSCN or something instead). That might be wrong, though
 
Think of Le Chatelier's Principle: when you apply a stress on a system it will naturally shift in a direction opposite that stress. So, if you add products to a reaction at equilibrium, it will shift back towards the reactants. If you add reactants, it will shift towards the products. Think of that.
 
I'm pretty sure the addition of Na+ drives the reaction towards the reactants side because it effectively lowers the concentration of SCN- by forming NaSCN.
 
No, Na+ is always soluble so it does not form a compound that would affect equilibrium, because the compound would simply dissociate. However, OH is insoluble and will bind with the free Fe3+, which then decreases the available reactant, which shifts equilibrium towards the reactants. As for the other two they both increase available reactant, shifting equilibrium towards the products.
 
and KooDellKah was right about the third one, it reacts with Fe3+ to form Fe(OH)3, which decreases the concentration of Fe3+ which makes it shift to the left.
 
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