Question

a) Rank the following according to the number of reducing groups in a 1% solution: maltose, sucrose, amylose, fructose and glucose.

b) How would your ranking change if you had 1M solution of each (instead of 1%)?

Answer 1

Compound	Molecular formula	Molar mass
Glucose	C6H12O6	180
Fructose	C6H12O6	180
Maltose	C12H22O11	342
Amylose	(C6H10O5)n	n x 162
Sucrose	C12H22O11	342

(a) Rank of reducing groups in 1% solution must be

Glucose = Fructose > Maltose > Amylose > Sucrose

Sucrose do not have reducing group. It is a non reducing sugar

One molecule of Glucose, Fructose, Maltose and Amylose have one reducing group each

but 1% solution conatin

  

  

Therefore higher the molar mass of a compound, lower the no. of molecules hence lesser the no. of reducing groups in 1% solution.

(b) Rank of reducing groups in 1 M solution should be Glucose = Fructose = Maltose = Amylose > sucrose

Because 1 mole of Glucose, Fructose, Maltose and Amylose contain some no. of molecules and reducing groups while sucrose do not have any reducing group.