MYTUTOR SUBJECT ANSWERS

1058 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...

11 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

154 SUBJECT SPECIALISTS

PremiumOliver B. GCSE Chemistry tutor, GCSE Biology tutor, GCSE Geology tuto...
£36 /hr

Oliver B.

Degree: Medicine (PhD) (Doctorate) - Bristol University

Subjects offered:Chemistry, Science+ 5 more

Chemistry
Science
Physics
Geology
Extended Project Qualification
Biology
-Personal Statements-

“I have been teaching here since 2013 and use various teaching styles depending on what helps you to learn best!”

PremiumFerdinand B. A Level Biology tutor, A Level Chemistry tutor, GCSE Che...
£30 /hr

Ferdinand B.

Degree: Medical Sciences (Bachelors) - Exeter University

Subjects offered:Chemistry, Maths+ 2 more

Chemistry
Maths
French
Biology

“Currently studying Medical Sciences. Very sporty, very sociable, and also a very supportive tutor! ”

£30 /hr

Vicky H.

Degree: Dentistry (Masters) - Leeds University

Subjects offered:Chemistry, Science+ 12 more

Chemistry
Science
Maths
Mandarin
Human Biology
English Literature
English Language
.UKCAT.
.BMAT (BioMedical Admissions)
-Personal Statements-
-Oxbridge Preparation-
-Medical School Preparation-

“Hi I'm Vicky, I'm a 2nd year dental student at the University of Leeds. I am friendly and patient and have a love for science, maths and teaching.”

About the author

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

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

How can I improve my exam technique?

Write an expression and units for equilibrium constant for this reaction: 2SO2(g)+O2(g)<-->2SO3(g)

Why does ice float on water?

What are the different forms of elemental carbon?

View A Level Chemistry tutors

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

mtw:mercury1:status:ok