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### ICE tables for reverse rxns

Posted: Sun Jan 19, 2020 10:50 pm
Should we know how to use ice tables for when the reverse reaction occurs in certain reactions? In what conditions can we tell that the reaction will shift left instead of right?

### Re: ICE tables for reverse rxns

Posted: Sun Jan 19, 2020 10:58 pm
You would treat the reverse reaction just how you treated the front reaction. You have initial concentrations and the only difference is that you minus x from the products and add x to the reactants, and then use the equallibrum concentrations and your K to solve for x.

### Re: ICE tables for reverse rxns

Posted: Sun Jan 19, 2020 11:01 pm
The reason we haven't dealt with reverse reactions in class is because usually we assign the chemical that we start with to be the reactant, so the reaction will go mostly in the forward direction and we can assume that the initial concentration will decrease be some amount (x).

### Re: ICE tables for reverse rxns

Posted: Sun Jan 19, 2020 11:04 pm
For some problems (i.e. 5I.25), you have to calculate the Q value first and then compare it with K. If Q<K, the reaction will move forward, and if the Q>K, the reactions will move in reverse. This is all relative to how the chemical reaction is written. Then, set up your Ka expression and ICE table accordingly, add x to the side of formation.

### Re: ICE tables for reverse rxns

Posted: Sun Jan 19, 2020 11:04 pm
You should be able to employ ICE table on reverse rxns the same way as you do it on rxns. Since products formation and reactants formation take at the same time as the reaction goes on, under the same temperature, you should get the same concentration result, whether you use reaction or its reverse reaction.

When the reaction quotient(Q) is bigger than K, which means that the concentration of products are higher than equilibrium concentration, to reach the equilibrium constant, more reactants must be produced. So you can say that the reaction is "shift" to the right, favoring reactants formation.

Hope this can help!