I used to stay up at Oxford and Cambridge during the interview period, when the colleges were awash with nervous-looking interviewees. Most asked me what they needed to do to win a place at the college, like there was a big secret that we all knew or a special handshake to use. I understand why they thought that way, even if you make it to interview, and most do not, the chances of being offered a place are slim. The truth is, there is no special handshake - every choice you have taken, every sacrifice you have made to study a little bit more than most has either prepared you for interview day or it hasn’t - once you are there in college, the best you can do is be yourself and hope that is what the tutors see.
Of course, before I went up for interview I had heard a few horror stories too, from the opening command ‘Impress me’ through to being quizzed about the identity of the tutor. Most of them are just stories, but I was asked ‘Who am I?’ in a Chemistry interview at Newcastle, so that one is true I suppose. I never found out what the interviewer thought he was, the obvious answer of ‘a Chemist’ didn’t work and I didn’t want to offend with ‘out of good questions?’ So yes, regarding the interview they could indeed ask anything, but don’t worry - there are some common themes that you might want to prepare for.
Firstly, the questions are not random
The first point to make is that the interviewers don’t ask you anything they fancy on the day. You have in fact already got an idea of the opening questions, these are likely to come from the content in your personal statement. The tutors and interviewers are genuinely keen to set you at ease at the beginning of the interview, so expect a few questions on anything you have done in relation to your subject and perhaps some of your extracurricular interests.
If you are applying to any top university, it is highly likely that they will also ask some stretch questions that either test your ability to solve problems (a core skill for a budding Chemist) or to see if you can cope with degree-level material. So, in this part of the interview, where they are asking things beyond A-level, what might come up?
Common topics for Chemistry interview questions
The universities are looking to replace their current first year undergraduates with students of similar capabilities. Because of this, they often choose topics that are covered early in the first term because this makes a direct comparison to their existing students very easy. They also like questions that can start with some A-level material and then be expanded or applied to novel situations. Popular topics for questions include:
- Anything mentioned explicitly on your personal statement
- Anything you bring in to the discussion during the interview
- Stereochemistry
- Shapes of molecules
- Organic mechanisms
- Kinetics and Energetics
- Lattice, ionisation and hydration enthalpies
- Chemistry in everyday phenomena
- Problem solving using moles
- Maths involving logs, calculus, and graphical interpretation of data
This isn’t an extensive list. You may also get some brain teasers or other mental agility problems, these were a particular favourite of my supervisor at Cambridge. It is still worth making sure you are competent and confident in the above areas though, as they are frequently probed at interview. You can prepare for this by reading some introductory undergraduate material or by having a few sessions with me to improve your subject knowledge. I have some suggested reading and example questions below.
Suggested reading
I have listed some good popular science books and magazines on this page. I suggest you read one or two of these before your interview, you might get the opportunity to weave a few anecdotes in to your answers and demonstrates that your interest in the subject is genuine.
For general chemistry, read through the introductory chapters on sterochemistry and physical chemistry from either the ‘Foundation’ editions of the Oxford Chemistry Primers or from Chemistry cubed. Stick with the first chapters and you will be well-equipped to answer some of the stretch questions.
Example questions
Here is a brief selection of (old) Oxford interview questions, with some suggested responses.
1. Explain why blowing on a hot drink makes it cool down faster.
At first glance, this is not a chemistry question, it is a physics question! Physical chemistry is a signifcant part of the course, and what the tutors are looking for here is depth of knowledge and your ability to use what you know to solve a new problem (also known as conceptual problem solving.)
The rate of evaporation of a liquid depends on the surface area of the liquid, the atmospheric pressure, and it's boiling point. Whilst you could mention blowing across the surface changes the surface area or pressure, what the interviewers really want you to talk about is what happens on the microscopic scale.
The key to solving the problem is using the Maxwell-Boltzmann distribution - evaporation happens when some of molecules have a kinetic energy exceeding that required to break the intermolecular forces between the particles in the liquid. Blowing on the surface removes molecules that have the highest kinetic energy, those that are in the right-hand tail of the Maxwell-Boltzmann distribution. Removing them drops the overall kinetic energy of the liquid and cools it down.
2. The rate of hydrolysis of (CH3)3CBr with hydroxide is ten thousand times faster in a mixture of ethanol and water than just with water. Why do you think that is the case?
This is an organic chemistry question on nucleophilic substituition. Some of the A-level specifications make the distinction between two different substition mechanisms (e.g. Edexcel) and the others generally don't, at least so far as examinations are concerned. It doesn't matter too much though, this question is probing whether you read further than your specification and if you can puzzle-out the answer.
The organic molecule will react via a SN1 mechanism, which happens through a series of steps including a cation intermediate. The formation of this intermediate is the rate-determining step of the reaction, and it can be shown using a simple reaction profile that anything that lowers the energy of the intermediate will reduce the activation energy of the rate-determining step, making the whole reaction faster.
All that remains is to explain how water stabilises the carbocation intermediate, which can be described in two ways: Firstly, the dielectric constant for water is higher than for ethanol, so water is better at stabilising emerging charges on a molecule. Secondly, water is more polar than ethanol and therefore water is better at stabilising the positive charge on the carbocation intermediate.
What are Oxford and Cambridge looking for in a future undergraduate?
Keith, my Physical Chemistry tutor, used to sum up what he was looking for in a candidate as ’the right attitude and aptitude’. I realise that isn’t particularly helpful, unless of course you already know an Oxbridge alumnus and therefore have some idea of what those two terms mean. So, it is better to look for the qualities that make for an impressive candidate at interview; for the common traits that the vast majority of students who get selected have in abundance. These are:
- Clear evidence of independent thinking
- Perseverance
- Enthusiasm for the subject and learning in general
In many ways, you prepare for Oxford or Cambridge from very early in life. Candidates that have thought about the links and deeper meaning of the ideas in their studies perform well at interview. Indeed, when answering an A-level question is it clear that students that think for themselves could easily go a step further in complexity. They have the spare mental capacity and have arranged their thoughts in a way they can be quickly accessed when approaching such problems.
All three qualities are synergistic, so you can’t really be weak in any of them without weakening the others. Perseverance is more than just keeping going, you need a thinking mind to try alternate approaches and the enthusiasm to do this regularly. Studying at Oxbridge means that there are no easy days, just easier days, so showing some grit isn’t something you can just do occasionally. Grit is really crucial in the eyes of the interviewers to demonstrate that you are likely to last the full three or four years required to graduate. With only a few places available at each college and increasingly tight budgets, they don’t want to take on a quitter or subject-switcher when they have to turn down so many others for each place.
As a final note, if you do get the opportunity to have an interview, make sure to be yourself. Don’t pretend to have knowledge or abilities you don’t actually have, the interviewers are experts and will quickly find you out! There were tales each year at the annual Chemistry dinner of candidates who made bold claims that evaporated with the first follow-up question - those guys were easy to reject. If you have the qualities that they are looking for, all you need to do is be relaxed and comfortable enough to show them. Do that and you stand an excellent chance of getting an offer.
Good luck!