1.1 Flashcards
What is a monomer? (1)
What is a polymer? (1)
(1) 1 individual molecule
(1) a LONG CHAIN of MANY REPEATED molecules/units
What does a glucose molecule do (structure-wise) since it’s a long chain? (2)
(1) it closes up on ITSELF
(2) to form a MORE STABLE RING
What is the structure & properties of monosaccharides? (5)
(1) they’re SIMPLE sugars
(2) they DISSOLVE in water easily
(3) has the formula = (CH2O)n
(4) & (5) they LINK TOG by CONDENSATION to FORM disaccharides & polysaccharides
What is the difference between a-glucose & B-glucose? (4m)
(2) a-glucose’s OH molecule is BELOW C1
(2) B-glucose’s OH molecule is ABOVE C1
What are isomers? (3)
(1) organic molecules…
(2) that have the SAME CHEM formula…
(3) but DIFFERENT STRUCTURAL formula
What are reducing sugars? (2)
What type of carbs are reducing sugars? (2)
(1) sugars that DONATE ELECTRONS…
(2) to REDUCE ANOTHER chemical
(1) ALL monosaccharides
(2) SOME disaccharides
What is the chemical in Benedict’s reagent? (1)
What pH is it? (1)
What colour is it? (1)
(1) Copper (ll) sulfate
(1) alkaline
(1) blue
What are the 2 aims of the Benedict’s test? (2)
(1) to test for the presence of a reducing sugar
(2) to approximately test for the conc. of a reducing sugar in a sample
What is the procedure of the Benedict’s test? (5)
(1) Add 2cm. of food sample
(2) Add 2cm. of Benedict’s reagent
(3) Heat the mixture…
(4) in a boiling water bath…
(5) for 5 minutes
What is the reduction word equation of the Benedict’s reagent? (3)
(1) copper (ll) sulfate —> copper (l) oxide
(2) using heat..
(3)..& using a reducing sugar
What type of test is the Benedict’s test? Why? (2)
(1) semi-quantitative
(2) because the colour of the precipitate can be used to estimate the approx. conc./amount of reducing sugar
What colour proves that the reducing sugar is highly conc. in the Benedict’s reagent? (1)
(1) red/orange/brown
“Suggest a way, other than comparing colour change, in which diff. conc. of reducing sugar could be estimated in Benedict’s test. & state what the result would be.” (3)
(1) dry the precipitate in each sample…
(2) & weigh it…
(3) the heavier the precipitate, the more reducing sugar is present.
“Explain why it’s not possible to distinguish between very conc. samples, even though their conc. are diff.?” (2)
(1) once all the reagent has been reduced, further amounts of reducing sugar can’t make a difference
(2) so the reducing sugar would be in excess
“Why does Benedict’s reagent turn red when heated with a reducing sugar?” (2)
(1) reducing sugar = donates electrons
(2) which reduces copper (ll) sulfate
