MYTUTOR SUBJECT ANSWERS

194 views

Using chemical reagents in test tubes, distinguish between isomers: A CH3CO(CH2)2CHOH, B CH3CH(OH)(CH2)2CHO and C C(CH3)2OHCOCH3

Answer:

*First draw out each compounds' structural formula (an image of the "shape and arrangement of the atoms in space"), then identify all functional groups in each compound.

*Add Tollens' reagent to all three, the compound which provides a silver mirror / precipitate, is compound B. This is because B is the only one to have an aldehyde group, which is oxidised by Tollens and gives a positive result. Ketones are NOT oxidised by Tollens and so give a negative result (no mirror).

*Next, add acidified potassium dichromate, formula Cr2O72-, to all three. A and B give a positive result for this test, a colour change from orange to green, as they both have either primary or secondary alcohols. C gives a negative result, no colour change, as it has a tertiary alcohol which won't be oxidised by the dichromate.

So:

Tollens = X, Cr2O= ✓ -> Compound A

Tollens = ✓ -> Compound B

Tollens = X, Cr2O7 = X -> Compound C

Conor M. A Level Chemistry tutor, A Level Biology tutor, A Level Math...

4 months ago

Answered by Conor, an A Level Chemistry tutor with MyTutor


Still stuck? Get one-to-one help from a personally interviewed subject specialist

71 SUBJECT SPECIALISTS

£20 /hr

Alexandra L.

Degree: Aeronautical and Aerospace Engineering (Bachelors) - Leeds University

Subjects offered: Chemistry, Physics+ 2 more

Chemistry
Physics
Maths
Further Mathematics

“About Me I’m an Aerospace Engineering student at Leeds University. I have long loved tinkering and seeing how things work; to me, science is just the formal extension of this curiosity. Throughout sixth form I helped run the school ...”

£20 /hr

Chris M.

Degree: MChem (Masters) - Oxford, St Catherine's College University

Subjects offered: Chemistry, Biology

Chemistry
Biology

“Hey,You've made it this far, now read a little about me and what you can expect, and hopefully get in touch.About me:I am reading chemistry at Oxford University and am currently working on a project to design a new type of spectr...”

MyTutor guarantee

£26 /hr

Sarah T.

Degree: PGCE (Masters) - Durham University

Subjects offered: Chemistry, Psychology+ 1 more

Chemistry
Psychology
Maths

“About me: In 2015 I graduated from Durham University. Whilst there I had the most amazing time studying Psychology, Chemistry and Education. Science has always interested me and I find it fascinating how we can use scientific methods ...”

About the author

Conor M.

Currently unavailable: for regular students

Degree: Biochemistry with a year in industry (Bachelors) - York University

Subjects offered: Chemistry, Maths+ 1 more

Chemistry
Maths
Biology

“About me: Hello! I'm Conor, a second year Biochemistry student at the University of York, with a fascination for all things to do with science! My broad degree course means I cover all sorts of interesting topics, ranging from Genetic...”

MyTutor guarantee

You may also like...

Other A Level Chemistry questions

What factors affect the equilibrium position and in what way?

Can you explain what stoichometry actually is and why the ratio is not the same as the number of moles?

What's the difference between an electrophile and a nucleophile?

The ratio between the molar mass of an alkene(A) and an alkyne(B) with the same number of carbon atoms is 1.05. Find the molecular formulas of the two hydrocarbons then write the reaction for how we can obtain the alkene A from the alkyne B.

View A Level Chemistry tutors

Cookies:

We use cookies to improve our service. By continuing to use this website, we'll assume that you're OK with this. Dismiss

mtw:mercury1:status:ok