Bromine water – this is liquid bromine dissolved in
Acidified potassium dichromate – H+/Cr2O72-
water – written as Br2(aq).
It’s ORANGE in colour & an OXIDISING AGENT
 Reacts rapidly (virtually instantly) if shaken with an alkene/alkyne);
bromine water is decolourised (orange to colourless). (ADDITION
REACTION)
 Reacts VERY VERY slowly with alkane and only in UV light and/or heat.
(SUBSTITUTION REACTION). Bromine water is decolourised very slowly
(orange to colourless) PLUS makes some HBr gas.
It oxidises a primary alcohol to an aldehyde and then to a
All sorts of stuff
that’s useful for
detecting a carboxylic
acid.
HEAT with conc.
Dilute NaOH (aq)
It oxidises a secondary alcohol to a ketone (same colour change).
sulfuric acid –
Acid-base reaction
with RCOOH to
make the salt
RCOONa
Tertiary alcohols aren’t oxidised by it.

Conc. H2SO4 (as




Litmus paper (blue to
red)
UI paper / solution
(green to orange)
Add a reactive metal
eg Mg or Zn – see
bubbles of gas (H2 gas)
Add a ___ carbonate
or ____ hydrogen
carbonate eg NaHCO3
– see bubbles of gas
(CO2 gas).
Has a “sharp” smell or
has an “acidic smell” or
a “vinegary smell”
dehydrating agent.
Turns an alcohol
into an alkene.
catalyst) and heat
with ROH + RCOOH
makes an ester –
esterification
Heat with dilute
sulfuric acid H+/H2O
– is ACID hydrolysis
of an ester – to
produce ROH &
RCOOH.
HEAT with dilute
NaOH (aq)
Alkaline hydrolysis
if ester – to produce
ROH & RCOONa ;
when this is with a
fat/oil to make soap
we call it
saponification
carboxylic acid!
RCH2-OH
H+/Cr2O72heat
RCHO
Heat alkene with dilute sulfuric acid H+/H2O
to add water across C=C and make an alcohol.
heat
RCOOH.
Orange dichromate ion is REDUCED to green chromium(III) ion Cr3+
Heat with acidified
potassium permanganate –
another oxidising agent
H+/MnO4- It’s purple
It will also oxidise a primary
alcohol to an aldehyde and a
carboxylic acid eg propan-1ol to propanal to propanoic
And the “odd” reaction of acidified
potassium permanganate ….. another
OXIDATION reaction & a test for
unsaturation / C=C double bond. Does
NOT need heat.
alkene  diol : yes – it has TWO
alcohol groups. Colour change purple
MnO4- to colourless Mn2+
Eg CH3CH=CH2  CH3CH(OH)CH2OH
acid. Colour change as purple
Mn2+ Secondary alcohol is
oxidised to a ketone.
propan-1,2-diol
H
H
H
H
H
MnO4- is reduced to colourless

H+/Cr2O72-
H
C
C
C
H
H
H
H
C
H
C
C
O
O
H
H
H
Tollens reagent, [Ag(NH3)2]+ ; warm with Tollens reagent
– a silver mirror shows aldehyde; Ag+ + e-  Ag . No
silver mirror with a ketone.
BIG HINT: “Has a characteristic smell” or “has a pleasant fruity smell” –
chances are it is an ESTER. Esters also insoluble in water – get 2 layers.
Fehlings solution or Benedicts
solution – contain Cu2+ ion; warm
with Fehlings / Benedicts solution –
an orange precipitate shows an
aldehyde; Cu2+ + e-  Cu. No change
with a ketone.
SOLUBILITY: Only the small polar molecules (C 1 to 3 or 4) are
soluble in water – ALL others make 2 LAYERS with water or an (aq)
reagent eg Br2 water or NaHCO3(aq) as they are either non polar
molecules or have a large non polar portion.