Hello! I was looking into haloalkane reactions and the factors which determine the proportion of nucleophilic substitution to elimination reactions. I read that ethanol is more conducive to elimination reactions than substitution reactions, it mentions it being less polar than water, which favours substitution. I also read that SN1 are favoured over SN2 reactions as the ethanol can stabilise the carbocation. However, I can't find a source that explains why ethanol favours elimination, it must be to do with the 'extent' of polarity of the molecule. Is it because the polarity of the molecule influences the stability of the carbocation, and as water is more polar, the carbocation is more stable and therefore substitution is favoured as the carbocation can exist for a longer period of time? I appreciate that is insufficient an explanation on it's own. So, taking in to consideration the activation energy, and that subsitiution has a lower activation energy, these two factors can be combined to produce an explanation: Subsitution is favoured in highly polar solvents as the carbocation is more stable and therefiore exists for longer, and as the ativaiton energy is lower, it is more likely to be achieved than elimination. In less polar solvents, the carbocation is less stable, and therefore elimination is more liekly to occur, even though it has a higher activation energy, the carbocation intermediate is going to be somewhat 'rare'. It seems confusing, as the classification (primary, secondary and tertiary) keeps popping up, and begs to be included! Any help appreciated, apologies that its quite long, an attempt seemed necessary. Many thanks, Nobahar.