Water

Question 1

What is a hydrogen bond?

Answer 1

A hydrogen bond is the force of attraction formed when
regions of a water molecule with a small positive charge
come close to the negatively charged region of another
water molecule.

Question 2

What function does hydrogen bonding in amino acids serve?

Answer 2

To maintain the structural stability of large protein molecules.

Question 3

What are Orbitals?

Answer 3

Orbitals are the regions around the atomic nuclei in which electrons can be found

Question 4

How many electrons do Hydrogen and Oxygen atoms have respectively?

Answer 4

Hydrogen-1

Oxygen-8 with 6 taking part in bond formation

Question 5

What shape does a water molecule take and why

Answer 5

A water molecule takes a tetrahedral shape because there is greater repulsion between the non-bonding electron pairs on the oxygen atom pushing the hydrogen atoms closer together

Question 6

Why is liquid water denser than ice

Answer 6

This is because water molecules are more closely packed in liquid water than in ice

Question 7

Why does oxygen have higher electronegativity than hydrogen

Answer 7

Because oxygen has a higher capacity to attract electrons than hydrogen

Question 8

“Water has a high surface tension” What does this mean ?

Answer 8

The surface between liquid water and air is relatively difficult
to puncture because a lot of energy is needed to force the
hydrogen-bonded water molecules away from one another

Question 9

What happens to Hydrogen bonds at different temperatures

Answer 9

At colder temperatures hydrogen bonds become fixed while at hotter temperatures hydrogen bonds break this is shown in liquid water becoming ice and liquid water becoming steam respectively

Question 10

Give an example of “Surface Tension”

Answer 10

Filling a clean glass with water. When the glass is nearly full,
continue adding water slowly and carefully. The surface tension allows the glass to be filled slightly above its rim without overflowing.

Question 11

Why is water a polar molecule

Answer 11

Because hydrogen atoms have regions of positive charge and oxygen has regions of negative charge the presence of the charge makes water a polar molecule

Question 12

What is Latent Heat of Fusion

Answer 12

It is the amount of heat energy needed to convert one unit amount of a substance from a solid to a liquid state

Question 13

What is the amount of heat energy needed to turn ice into liquid water and why is this value so high

Answer 13

6.0 KiloJoules is needed to convert ice into solid water and this value is high because large amounts of energy are needed to break the hydrogen bonds in the ice. NB The same amount of heat energy(6.0 kilojoules) is released by liquid water to be converted into ice

Question 14

What is the heat of vaporization and what name is given to its process

Answer 14

This is the amount of heat needed to turn liquid water into gaseous water.It is called evaporation

Question 15

How does evaporation occur

Answer 15

It occurs when liquid water absorbs the heat of the environment, the hydrogen bonds holding the molecules together begin to move more and break bonds allowing them to move freely that is become a gas

Question 16

Explain the properties of water at room temperature

Answer 16

Nearly colourless with a hint of blue, tasteless and odorless liquid

Question 17

What does the viscosity of water dictate

Answer 17

The viscosity of water dictates the force needed for objects to move through water which increases when cold and increases with heat

Question 18

What does the viscosity of water dictate

Answer 18

The viscosity of water dictates the force needed for objects to move through water which increases when cold and increases with heat

Question 19

Why does water stick to itself and why does it have high adhesion properties

Answer 19

Because it is a polar substance

Question 20

What is the difference between hydrophilic and hydrophobic substances

Answer 20

Hydrophilic substances are substances that are water-loving and dissolve well in water example(salts, and sugars). Hydrophobic substances are substances that are water fearing and do not dissolve well in water (fats and oils)

Question 21

What happens to an ion when it enters water

Answer 21

It becomes surrounded by water molecules. Due to their relatively small sizes, it allows many water molecules to surround the solute molecule

Question 22

Why do non-polar molecules stay together in water

Answer 22

It is more favorable for water molecules to hydrogen bond with each other than engage in Van der Waals interaction with non-polar molecules