Need help! onnnnnncceee againnn (1 Viewer)

[mkv_86]

'Explain the difference between starch and cellulose, provide equations to support your answer' (3 marks)

What should I write about to earn 3 marks?


Much thanks

 

[supR]

Both starch and cellulose are made of glucose monomers through condensation polymerisation. Each monomer for starch is in the same orientation whilst cellulose has each second monomer rotated 180 degrees. That’s the main difference I can find, and the equations should show this I guess. Not entirely sure how to help for 3 marks, sorry :/


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[jazz519]

The structure (describe them as condensation polymers define that):

Cellulose is formed from reaction of beta glucose monomers (with every second molecule inverted), which form a 1,4 -glycosidic linkage and in the process results in the elimination of a small molecule (water). Hence it is a condensation polymer. Similarly, starch is also a condensation polymer, however it is formed from the linking of alpha glucose monomers that combine in the same orientation.

An equation showing formation (structural is probably best)

Now for the last mark consider what this difference in structure means in terms of physical properties (i.e. Cellulose molecules are linear, unbranched and have hydrogen bonds so can align side by side into high density crystalline fibres.

However, the strong array of hydrogen bonds between hydroxyl (OH) groups which holds strands together is much stronger than the interactions between water and cellulose, and thus cellulose is insoluble in water.

While starch is less stronger than cellulose in terms of IMFs, allowing it to dissolve in water

 

[mkv_86]

The structure (describe them as condensation polymers define that):

Cellulose is formed from reaction of beta glucose monomers (with every second molecule inverted), which form a 1,4 -glycosidic linkage and in the process results in the elimination of a small molecule (water). Hence it is a condensation polymer. Similarly, starch is also a condensation polymer, however it is formed from the linking of alpha glucose monomers that combine in the same orientation.

An equation showing formation (structural is probably best)

Now for the last mark consider what this difference in structure means in terms of physical properties (i.e. Cellulose molecules are linear, unbranched and have hydrogen bonds so can align side by side into high density crystalline fibres.

However, the strong array of hydrogen bonds between hydroxyl (OH) groups which holds strands together is much stronger than the interactions between water and cellulose, and thus cellulose is insoluble in water.

While starch is less stronger than cellulose in terms of IMFs, allowing it to dissolve in water

Thanks again jazz!

 

[jazz519]

Both starch and cellulose are made of glucose monomers through condensation polymerisation. Each monomer for starch is in the same orientation whilst cellulose has each second monomer rotated 180 degrees. That’s the main difference I can find, and the equations should show this I guess. Not entirely sure how to help for 3 marks, sorry :/


Sent from my iPhone using Tapatalk

Be careful with this you have to say beta glucose (cellulose) and alpha glucose (starch)