Chemistry Personal Statementfor Oxford, Cambridge & Imperial

When the 2022 Nobel Prize in Chemistry was awarded for click chemistry and bioorthogonal chemistry, what held my attention was not the headline about targeted medicines, but a chemical idea: a reaction is valuable when it keeps doing the intended thing even in a crowded, messy system. Most of the chemistry I had met at school looked cleaner than this. Equations balanced, products appeared, and side reactions felt like something that happened off the page. Reading about Carolyn Bertozzi, Morten Meldal and K. Barry Sharpless made me realise that selectivity is not a decorative extra in chemistry; it is often the whole problem. I became interested in how chemists make one pathway dominate when several are possible, and why conditions that look minor on paper can completely change an outcome. That is why I want to study chemistry at university. I am drawn to areas where mechanism, kinetics and practical constraints meet, especially catalysis and synthesis, because they force you to explain not only whether a transformation is possible, but why one route wins over others. The question I keep returning to is still the one behind that Nobel Prize: how chemists make reactions selective enough to be useful.

That question became more concrete during organic chemistry. Halogenoalkanes first seemed predictable, but comparing substitution with elimination made me notice how unstable the word "favour" really is. The same starting material can give different major products depending on temperature, solvent, base strength and structure. That shifted mechanisms for me from something to memorise into something to reason with. James Keeler and Peter Wothers' Why Chemical Reactions Happen strengthened that shift. Their explanation of collisions, entropy and energy corrected my habit of treating enthalpy as the whole story. I started to think more carefully about why a reaction can be feasible overall yet still slow, or why the most stable product is not always the one formed first. Kinetic and thermodynamic control stopped being two terms to revise and became a useful way of understanding why synthesis is full of trade-offs rather than tidy certainties. My most detailed independent work came from wanting to test that habit against real data. In an EPQ-linked investigation, I studied the acid-catalysed iodination of propanone and used a colorimeter to track the decrease in iodine absorbance over time. I varied propanone, acid and iodine concentrations separately, plotted concentration-time graphs in Python and used initial rates to estimate the rate law. My first results looked neat, but the apparent order in iodine shifted between runs, which made the conclusion feel suspicious rather than impressive. After tracing this back to temperature drift, I repeated the method with a water bath, freshly prepared solutions and replicate trials. The improved data suggested dependence on propanone and acid concentration but much less on iodine itself, which pointed me towards enol formation as the slower step. What mattered most was not that the experiment "worked" in the end, but that it showed me how much chemical explanation depends on the quality of the measurements underneath it.