Unit Two - Biochemistry - Properties of Water

Question 1

What is water’s molecular structure?

Answer 1

h2o

Question 2

What type of bonds do hydrogen and oxygen form in water?

Answer 2

Covalent bonds

Question 3

What are covalent bonds?

Answer 3

A chemical bond formed when electrons are shared between two atoms

Question 4

What are the charges of water?

Answer 4

Oxygen - partially negative charge
Hydrogen - partially positive charge.

Question 5

Why is hydrogen and oxygen charges so different?

Answer 5

Oxygen attracts SO much more electrons than hydrogen

Question 6

Is water polar or nonpolar? Why? (4)

Answer 6

1. Polar
2. Uneven distribution of electrons
3. Creates different charges between atoms
4. Enables water’s unique properties.

Question 7

What are hydrogen bonds?

Answer 7

Attraction between two polar molecules

(Due to Polarity)

This enables cohesion, adhesion, surface tension and capillary action.

Question 8

Are hydrogen bonds weak or strong and why?

Answer 8

Hydrogen bonds are weak because they are making and breaking at a fraction of a second. However, numerous hydrogen bonds exist at once, so there is a lot of attraction overall.

Question 9

Why is water’s high specific heat important to living things? (2)

Answer 9

1. Water keeps environment at constant temp.
2. Endotherms can resist environmental changes in temperature because of water in the blood.

Question 10

WHY does water have a high specific heat? (3)

Answer 10

1. Water loves to form hydrogen bonds
2. Takes a lot of energy to break the bonds
3. To heat the water.

Question 11

What is cohesion?

Answer 11

Water molecules stick to each other.

H - Bonds form

Question 12

How does surface tension form? (3)

Answer 12

1. At water’s surface
2. There’s less adjacent water molecules for bonding
3. Hydrogen bonds are reinforces with between molecules.

Question 13

What is adhesion? (4)

Answer 13

Water sticks to other polar objects

Question 14

How does capillary action occur? (Adhesion, Cohesion, Surface Tension, 4)

Answer 14

1. Adhesion - Water molecules adhere to the polar substance
2. Cohesion - Pulls other water molecules up with it
3. Surface Tension - Maintain meniscus, creating a pressure difference that pull more molecules up the tube

This causes the water to rise in the tube, even against gravity

Question 15

Definition of Surface Tension (2)

Answer 15

1. A thin and invisible skin at the surface
2. Minimizes the Surface Area

Question 16

HOW does surface tension connect to the xylem?

Answer 16

When water sticks together and to a surface, it creates surface tension

Like adding water to the penny, you can only add so much and the water will break over the side.That can be measured with the drops on the penny and other scientific ways. Water always has surface tension, h bonding, cohesion, adhesion, polarity

Question 17

How does water relate to the xylem? (Cohesion, Adhesion, Surface Tension)

Answer 17

1. Cohesion - Keeps water molecules sticking together, forming a continuous column
2. Adhesion - Helps water molecules stick to the walls of the xylem vessels, aiding their upward journey
3. Surface tension - maintains stability of the water column, preventing air bubbles from breaking it apart.
4. Negative pressure created by transpiration pulls more water up from the roots

Question 18

What is the analogy that helps explain negative pressure?

Answer 18

Think of it like sucking on a straw. When you create a lower pressure inside the straw by sucking, the liquid is pulled up from the glass to fill the space. Similarly, transpiration creates a pulling effect that draws water up through the xylem vessels in plants.

Question 19

Why is ice less dense? (3)

Answer 19

1. Molecule movement decreases
2. Hydrogen bonds stabilize
3. Holds molecules farther apart