Question

activity b: dehydration synthesis
get the gizmo ready

• select the dehydration tab.

question: what occurs when two glucose molecules bond?

1. infer. glucose is an example of a monosaccharide, the simplest type of carbohydrate. a disaccharide is made from bonding two monosaccharides together.

what do you think the prefixes mono - and di - mean? mono - __________ di - __________

1. predict: turn on show description. drag both glucose molecules into the building region. observe the highlighted region. what do you think will happen to the atoms in this region when the glucose molecules bond?

1. run gizmo. click continue and watch the animation.

a. what happened? ____________
b. what was removed from the glucose molecules when they bonded to form maltose?

1. infer. based on what you have seen, create a balanced equation for the dehydration synthesis reaction. (recall that the formula for glucose is c₆h₁₂o₆.) you will have to determine the formula of maltose yourself.

turn on show current formula/equation to check your answer.

1. summarize: use what you have observed to explain what occurs during a dehydration synthesis reaction.

1. apply: a trisaccharide is a carbohydrate made of three monosaccharides. what do you think would be the chemical formula of a trisaccharide made of three bonded glucose molecules?

Explanation:

Step1: Define prefixes

Mono - means one. Di - means two.

Step2: Predict atom changes

When two glucose molecules bond in dehydration synthesis, an -OH (hydroxyl) group from one glucose and an -H (hydrogen) from the other combine to form water ($H_2O$). The remaining atoms form a covalent bond to create a disaccharide (maltose).

Step3: Analyze Gizmo results

A. Two glucose molecules bonded to form maltose and a water molecule was produced.
B. A water molecule ($H_2O$) was removed.

Step4: Create balanced equation

The formula for glucose is $C_6H_{12}O_6$. When two glucose molecules undergo dehydration synthesis to form maltose ($C_{12}H_{22}O_{11}$) and water ($H_2O$), the balanced equation is $2C_6H_{12}O_6
ightarrow C_{12}H_{22}O_{11}+H_2O$.

Step5: Summarize dehydration synthesis

In a dehydration synthesis reaction, two smaller molecules (such as monosaccharides) bond together. A water molecule is removed as a by - product as a result of the formation of a covalent bond between the two molecules.

Step6: Determine trisaccharide formula

Each glucose is $C_6H_{12}O_6$. When three glucose molecules bond through two dehydration synthesis reactions (removing two $H_2O$ molecules), the formula for the trisaccharide is $3C_6H_{12}O_6 - 2H_2O=C_{18}H_{32}O_{16}$.

Answer:

1. Mono - one; Di - two
2. An - OH from one glucose and an - H from the other combine to form water; remaining atoms bond to form maltose.
3. A. Two glucose molecules formed maltose and a water molecule was produced. B. A water molecule ($H_2O$)
4. $2C_6H_{12}O_6

ightarrow C_{12}H_{22}O_{11}+H_2O$

1. Two smaller molecules bond, and a water molecule is removed as a by - product due to covalent bond formation.
2. $C_{18}H_{32}O_{16}$