Lecture 3: Water And Life

Question 1

In a polar molecule opposite ends have ______charges

Answer 1

Opposite

Question 2

Polar molecules are

Answer 2

The difference in electronegativities of hydrogen and oxygen

Question 3

In relation to electronegativity oxygen has a

Answer 3

Partial negative charge

Question 4

In relation to electronegativity hydrogen has a

Answer 4

Partial positive charge

Question 5

Polarity allows

Answer 5

Water molecules to form hydrogen bonds with each other.

Question 6

Hydrogen bonds are

Answer 6

Weak electrical interaction between a hydrogen atom (with a partially positive charge) and another atom (oxygen or nitrogen) with a partially negative charge

Question 7

Cohesion

Answer 7

Attraction between like molecules

Question 8

Adhesion

Answer 8

Attraction between different molecules

Question 9

Surface tension is the

Answer 9

Measure of how hard it is to break or stretch surface of a liquid

Question 10

(In surface tension) At air-water interface is an

Answer 10

Ordered arrangement of water molecules, hydrogen-bonded to one another and to water below, but not to air above

Question 11

In surface tension, water behaves as if covered by an invisible film, aka

Answer 11

It resists any force that increases surface area

Question 12

Specific heat of a substance

Answer 12

Amount of heat that must be absorbed or lost for 1 g of that substance to change its temperature by 1 degree Celsius

Question 13

As molecules increase in polarity their ability to form hydrogen bonds __________, and it takes _______ energy to change their temperature

Answer 13

Increases, more

Question 14

Water is denser as a _________ than as a ________

Answer 14

Liquid; solid

Question 15

There’s more water molecules in a given volume of liquid than in

Answer 15

The same volume of solid water/ice

Question 16

Ice floats in liquid water because

Answer 16

Hydrogen bonds form a repeating crystal structure which equal more “ordered” and large amount of space between molecules meaning its less dense

Question 17

In liquid water, H-bonds are constantly

Answer 17

Being broken and formed

Question 18

In liquid water, molecules are pack more closely together than in the solid phase, which means it is

Answer 18

More dense

Question 19

Hydrophilic is a

Answer 19

Substance that has an affinity for water (water-loving); contains ionic and polar compounds

Question 20

Hydrophobic is a

Answer 20

Substance that doesn’t have an affinity for water (water-fearing); contains nonionic and nonpolar (lipid/fats) compounds

Question 21

A hydrogen atom in a H-bond between 2 water molecules can

Answer 21

Shift from one to another

Question 22

An H atom leaves its electrons behind and is transferred as a

Answer 22

Proton or hydrogen ion

Question 23

Hydrogen ion symbol

Answer 23

H+

Question 24

Hydronium ion symbol

Answer 24

H3O+

Question 25

When a hydrogen atom leaves its electron behind and is transferred as a proton, the molecule with the extra proton is a __________. The molecule that lost a proton is a ___________.

Answer 25

Hydronium ion, often represented as H+; Hydroxide ion (OH-)

Question 26

An acid is

Answer 26

A substance that increases H+ concentration of a solution. It donates an additional H+(hydrogen ion)

Question 27

A base is a

Answer 27

Substance that increases H+ concentration of a solution. It accepts an H+

Question 28

Acidic solution as have pH values

Answer 28

Less than 7 pH decreases as H+ concentration increases

Question 29

Basic solutions have pH values

Answer 29

Greater than 7 pH increases as H+ concentration decreases