The formula for glucose is C6H12O6. What is the formula for a polymer made by linking ten glucose molecules together by dehydration synthesis?

Question

A.  C60H111O51
B.  C60H120O60
C.  C60H100O50
D.  C60H102O51

Clarify Question
· What is the key concept addressed by the question?
· What type of thinking is required?
· What key words does the question contain and what do they mean?

Gather Content
· What do you know about dehydration synthesis? How does it relate to the question?

Consider Possibilities  
· What other information is related to the question? Which information is most useful?

Choose Answer
· Given what you now know, what information and/or problem solving approach is most likely to produce the correct answer?

Reflect on Process
· Did your problem-solving process lead you to the correct answer? If not, where did the process break down or lead you astray? How can you revise your approach to produce a more desirable result?


Answer 1

D.  C60H102O51

Clarify Question
· What is the key concept addressed by the question?
        o The question asks about the net reaction for a dehydration synthesis.
· What type of thinking is required?
        o You are being asked to analyze choices for the product of a dehydration synthesis reaction and choose the correct answer.
· What key words does the question contain and what do they mean?
        o Dehydration synthesis – a reaction used to join monomers together to form a polymer.  As each monomer is added, a molecule of water is lost, this is why it is considered a dehydration reaction.

Gather Content
· What do you know about dehydration synthesis? How does it relate to the question?
        o Dehydration synthesis is used to make polymers out of monomers.  If 10 glucose molecules are joined together then it would make sense to simply multiply the number of each atom in glucose by 10 to calculate how many would be present in the polymer.  Based on this you would obtain the answer C6H12O6 x 10 = C60H120O60.

Consider Possibilities  
· What other information is related to the question? Which information is most useful?
        o One additional thing to consider is that a water molecule is lost as each glucose is joined together.  If there are 10 glucoses joined together, there would be 9 total dehydration reactions that took place.

Choose Answer
· Given what you now know, what information and/or problem solving approach is most likely to produce the correct answer?
        o Water has the chemical structure H2O.  If a water molecule is lost in each dehydration reaction a total of 9 H2O would be lost for a total loss of H18O9.  The formula of the final polymer will then be C60H120O60 - H18O9 = C60H102O51

Reflect on Process
· Did your problem-solving process lead you to the correct answer? If not, where did the process break down or lead you astray? How can you revise your approach to produce a more desirable result?
        o This question asked you to analyze a dehydration synthesis reaction to determine the chemical formula of the final product. If you got the correct answer, great job! If you got an incorrect answer, where did the process break down? Did you realize that if there are 10 glucose molecules in the final polymer you would need to start by multiplying the formula of glucose by 10?  Did you realize that even though there were 10 glucose molecules there would only be 9 dehydration reactions?  Did you know to subtract the 9 water molecules from the formula to get the final answer?