Student Exploration: Dehydration Synthesis
Vocabulary: carbohydrate, chemical formula, dehydration synthesis, disaccharide, glucose, hydrolysis, monosaccharide, polysaccharide, valence
Prior Knowledge Questions (Do these BEFORE using the Gizmo.)
If you exercise on a hot day, you need to worry about dehydration. In this context, what do you think dehydration means?
Astronauts and backpackers often bring dehydrated food. What do you think dehydrated food is?
What do rice, potatoes, and sugar have in common? They are all foods rich in carbohydrates. Carbohydrates are an important energy source for your body. The basic building block of most carbohydrate compounds is the molecule glucose. Using the Dehydration Synthesis Gizmo™, you will learn about the structure of a glucose molecule and how glucose molecules can be joined together to make larger carbohydrate molecules.
To begin, select the CREATE GLUCOSE tab.
Look at the chemical formula for glucose. How many carbon (C), hydrogen (H), and oxygen (O) atoms are found in a molecule of glucose? C:_______ H:__O:_______
Turn on Show chemical structure. Each black sphere represents a carbon, hydrogen, or oxygen atom. The lines connecting the spheres represent chemical bonds.
How many black spheres are in the diagram? _______
How does this relate to the number of carbon, hydrogen, and oxygen atoms in the chemical formula for glucose? •
Build a glucose molecule
Get the Gizmo ready:
Be sure the CREATE GLUCOSE tab is still selected.
Introduction: Each element tends to form a certain number of chemical bonds. This value is the valence of the element. For example, a carbon atom has a valence of four.
Goal: Construct a molecule of glucose
Identify: The structure of a water molecule (H2O) can be written as H-O-H, with each dash representing a chemical bond. Count the number of bonds the oxygen and hydrogen atoms form in a water molecule.
What is the valence of oxygen? _______