• Carbohydrates are • Green plants contain a
special pigment called
compounds made of CHLOROPHYLL which traps
Carbon, Hydrogen and sunlight. Plants use this
Oxygen. energy along with CO2 gas
and Water to make food –
• They are made in Glucose (sugar), Oxygen is
PHOTOSYNTHESIS also released.
• This process is carried • CO2 + H2O —>O2 + C6H12O6
out in the leaves of • Light and Chlorophyll must
be present for the reaction to
Green Plants. take place.
Examples of Carbohydrates
• Carbohydrates contain the elements C.H. and O.
• There are twice as many H in the molecules as C and
• They can be split into 3 main groups: monosaccharides,
disaccharides and polysaccharides.( saccharide =
• Monosacharides – formula C6H12O6 e.g. glucose,
fructose and galactose. They are isomers.
• Disaccharides – formula C12H22O11 e.g.. Lactose,
maltose, sucrose. They are isomers
• Polysaccharides – (C6H10O5)n e.g.. Cellulose, starch,
• Respiration is when • When we eat food the energy
Carbohydrates are trapped in the food is
broken down to release
energy. Oxygen must be • We can show that energy is
contained in food in the lab.
• CO2 and H2O are • Exploding custard tin.
produced. • When we burn sugar in the
• C6H12O6 +O2 —>CO2 + lab we can test the products.
H2O ( energy is released) • We use lime water and
collect the colourless liquid
produced in a U tube. (CO2 +
The Carbon Cycle
• These 2 reactions working • Photosynthesis and
together make part of the respiration are the chemical
Carbon Cycle. opposites of one another.
• Humans can destroy the When they work together
balance by: without intervention they
Burning – CO2 is produced. ensure the correct balance of
gases in the air.
• Chopping down trees/plants-
less photosynthesis therefore • We breathe out CO2. Plants
too much CO2 and less O2 in use this in Photosynthesis.
the atmosphere. They give out O2. We require
this for respiration.
• When any C compound is
burned CO2 is produced • Plants go through respiration
when there is no sunlight.
( Fossil Fuels)
Testing for Carbohydrates
• Iodine test • Benedict’s Test
• Starch will turn Iodine (Fehling’s)
solution from brown to • Monosaccharides and
blue/black. disaccharides – except
sucrose will turn
Benedict's reagent from
blue to orange.
Properties of Carbohydrates
• Mono and disaccharides • Starch is not sweet
are usually soluble in tasting. It forms a colloid
water. If you shine a in water – it looks as if it
beam of light through it, has dissolved but if you
the light will pass strait shine a beam of light
through. through it you can see
• They are sweet tasting. the particles. The
molecules are too big to
Making long chain Carbohydrates
• Disaccharides and polysaccharides are made
when monosaccharides undergo condensation
polymerisation. 1 water molecule is released for
every two monomers joined.
• Glucose +Glucose —> maltose + water
• C6H12O6 + C6H12O6 —> C12H22O11 + H2O
Breaking Long Chain Carbohydrates
• Hydrolysis is the break down of Carbohydrates into
smaller molecules. E.g. Starch being broken down into
Glucose. This is the opposite of polymerisation. A
water molecule has to be added back – hydrolysis.
• An acid or enzyme has to be present for this to happen.
• Sucrose breaks down to give 1 fructose molecule and 1
• Sucrose —> glucose + fructose
C12H22O11 Acid/enzyme C6H12O6 + C6H12O6
• When we eat starchy food our bodies break it down into
smaller molecules so they can pass through the gut wall
into the blood.
• This is another example of Hydrolysis.
• It starts off in the mouth. Saliva contains an enzyme,
amylase, which starts to break down the starch.It
continues in the stomach, where acid is found.
Digestion in the lab
• Place starch solution in 3 different test-tubes
• To one add amylase
• To another add acid
• Add nothing to the third
• Place all 3 in water bath at 37C ( body T)
• Test each test-tube with Benedict’s solution after a few
• The test-tubes with the acid and amylase will turn
orange – proving the starch has been broken down into
Identifying the products of
• Look at how far each • We can use
spot has travelled. CHROMATOGRAPHY
• Spot the paper with:the
• Compare the spots of the
products of hydrolysis of
mono and disaccharides starch(H1) and sucrose(H2)
with H1 and H2. and mono and disaccharides.
• Match up the spots at • Do not mix the spots.
same level to identify the • Let the chromatography run.
which type of sugar is • Look at results
produced in Hydrolysis.
• Equation • This is the process of
• C6H12O6 →C2H5OH making Alcohol from
+CO2 • Small sugar molecules
can be converted to
• C2H5OH is ethanol. alcohol, using the
• It is part of the Alkanols. enzyme Zymase, which
• This is another is found in yeast.
homologous series. • Carbon dioxide is also
• Alcohol slows down our • You can make alcohol
reactions. from any carbohydrate
• Too much can damage source.
our livers. • Source Alcohol
• It can also be used as a • Barley Beer/Whiskey
fuel. • Apples Cider
• Grapes Wine/Sherry
• Potatoes Vodka
• We place the impure alcohol • WE can increase the
in the distillation flask with
antibumping granules. strength of alcohol by
• Heat up the mixture. distilling it. This removes
• Ethanol has BP of is 78C, any impurities.( normal
water is 100C. alcohol concentration in
• The alcohol will boil first, fermentation is 15% -
pass along delivery tube and any stronger and the
condense back to liquid.
enzyme is destroyed –
• WE can repeat this process
to purify it even more. DENATURED)
• Spirits are distilled.
• Step 3 Fermentation • Step 1 – Malting
• Yeast added – Glucose
brakes down into ethanol and • Barley is Hydrolysed into
Carbon dioxide Maltose (uses enzyme in
• Step 4 – Distilling Barley) – Green Malt
• To purify whisky – increase • Step 2 – Mashing
• Step 5 – Blending • Green Malt roasted on
• Mix different whisky’s then peat fire and Mashed
bottle them( malt whisky - not