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About me

Who am I?

I am a French PhD student in chemistry at the university of Bristol. As far as I remember I have always been fascinated by sciences and I ldo ove sharing this passion by helping students.

Tutoring is to my eyes extremely rewarding. I have been teaching for many years, first horse-riding to beginners, and later science to GCSE to 1st academic year students.

I graduated in France with both a M.Sc in chemistry and in biochemistry - drug development and I had various experience in English-speacking environment, including an Erasmus semester in Belfast and my Master thesis at the University of Cambridge.

What does a tutorial look like?

Who knows better than you what needs to be covered! I have always oriented the sessions according to the students need. All I ask my students is to let me know what topic they would like to work on and what they want to do: coming to the basics, looking for exercises or exams done in class, or going further with more complex problems. this method has been very successful sofar, with happy students and good marks.

Willing to pursue your studies in France, or just to travel there?

As a native speacker I would be more than happy to help you with discussion sessions in French on various topics according to your needs. I can also teach any scientifical subject in French to ensure you won't get lost once in your french university!

Any question?

You are very welcome to contact me by intern mail if you have any special inquiry or availabilities, I will always do my best to find a solution.

Subjects offered

SubjectLevelMy prices
Chemistry A Level £20 /hr
French A Level £20 /hr
Maths A Level £20 /hr
Chemistry GCSE £18 /hr
Maths GCSE £18 /hr
Science GCSE £18 /hr
Chemistry IB £20 /hr

Qualifications

QualificationLevelGrade
Chemistry & Drug Development (BioChemistry)Masters Degree1st
Drug Development - BiochemistryMasters Degree1st
ChemistryBachelors Degree1st
ScienceBaccalaureate1st
Disclosure and Barring Service

CRB/DBS Standard

No

CRB/DBS Enhanced

No

Ratings and reviews

5from 82 customer reviews

Darren (Parent) October 11 2016

great lesson,thanks Sarah

Ash (Parent) October 4 2016

After second tutorial with Sarah our daughter began to enjoy studying Chemistry.

Arshad (Parent) October 10 2016

Hi Sarah, Please could you give a review of how Saaliha's tuition is going. Regards Arshad

Rosanna (Parent) September 3 2016

Thanks again Sarah for your clear explanations, friendly and professional approach.
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Questions Sarah has answered

How to choose a pH indicator for a titration?

Although it can seem a unusual question it simply requires to have understood the basis of a titration. First of all, what is a pH indicator? It is simply an acid-base compound whose acid and base form present different colours. This makes these compounds often used to determine the pH of a s...

Although it can seem a unusual question it simply requires to have understood the basis of a titration.

First of all, what is a pH indicator? It is simply an acid-base compound whose acid and base form present different colours. This makes these compounds often used to determine the pH of a solution - and to determine the concentration of an unknown acid or basic solution.

Let’s take an example: the titration of a hydrochloric acid solution by a sodium hydroxide solution with BBT (bromothymol blue). A few drops of BBT are added to the acid solution which takes the colour of the BBT acid form – ie yellow. The hydroxide sodium solution is then added dropwise to the acid solution. The hydroxide ions reacts with the oxonium ions of the acid solution to give water according to the equation: H3O+ + HO- = 2 H2O.  As long as there are H3O+ ions in the reaction mixture the hydroxide ions will be neutralized: the solution will stay acidic and keep the yellow colour of the BBT. However oxonium ions are also consumed, and the reaction basicity increases slowly, until all the oxonium ions have been consumed: the equivalence is reached. Now what is the consequence on the solution colour? The acid and basic forms of the colour indicator are in equilibrium, therefore the colour is in-between the acid and the basic colours. In the case of BBT the solution will turn green. If hydroxide ions are added beyond this moment, there won’t be any more acid species to react with them and the pH of the solution will increase. It will therefore takes the colour of the basic form of the pH indicator – in this case blue.

Now why is BBT a good pH indicator for this titration? The key point is that the colour change occurs when the equivalence is reached. The colour depends on the dominance of either the acid or the basic form of the indicator at a given pH. This information is given by the pKa of the acid-base couple. It is usually assumed that at pH = pKa – 1 the acid form dominates whereas at pH = pKa + 1 the basic form dominates. Therefore to have the colour change when the equivalence is reached the pH then must be as close as possible of the pKa of the indicator. Going back to the example, the pH of the titration of a strong acid by a strong base is 7 – which is also the pKa of BBT.

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1 year ago

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