Unit 1, Chapter 3

Question 1

polar covalent bonds

Answer 1

a covalent bond between atoms that differ in electronegativity. the shared electrons are pulled closer to the more electronegative atom, making it slightly negative and the other atom slightly postiive

Question 2

polar molecule

Answer 2

a molecule (such as water) with an uneven distribution of charges in different regions of the molecule

Question 3

cohesion

Answer 3

the linking together of like molecules, often by hydrogen bonds

Question 4

adhesion

Answer 4

the clinging of one substance to another, such as water to plant cell walls by means of hydrogen bonds

Question 5

surface tension

Answer 5

a measure of how difficult it is to stretch or break the surface of a liquid. water has a high surface tension because of the hydrogen bonding of surface molecules

Question 6

thermal energy

Answer 6

kinetic energy due to the random motion of atoms and molecules; energy in its most random form

Question 7

temperature

Answer 7

a measure in degrees of the average kinetic energy (thermal energy) of the atoms and molecules in a body of matter

Question 8

kinetic energy

Answer 8

the energy associated with the relative motion of objects. moving matter can perform work by imparting motion to other matter

Question 9

heat

Answer 9

thermal energy in transfer from one body of matter to another

Question 10

calorie (cal)

Answer 10

the amount of heat energy required to raise the temperature of 1g of water by 1 degree Celsius; also the amount of heat energy that 1g of water releases when it cools by 1 degree Celsius. the Calorie (with a capital C), usually used to indicate the energy content of food, is a kilocalorie

Question 11

kilocalorie (kcal)

Answer 11

a thousand calories; the amount of heat energy required to raise the temperature of 1kg of water by 1 degree Celsius

Question 12

joule (J)

Answer 12

a unit of energy: 1 J = 0.239cal; 1 cal = 4.184J

Question 13

specific heat

Answer 13

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

Question 14

heat of vaporization

Answer 14

the quantity of heat a liquid must absorb for 1g of it to be converted from the liquid to the gaseous state

Question 15

evaporative cooling

Answer 15

the process in which the surface of an object becomes cooler during evaporation, a result of the molecules with the greatest kinetic energy changing from the liquid to the gaseous state

Question 16

solution

Answer 16

a liquid that is a homogenous mixture of two or more substances

Question 17

solvent

Answer 17

the dissolving agent of the substance. water is the most versatile solvent known

Question 18

solute

Answer 18

a substance that is dissolved in a solution

Question 19

aqueous solution

Answer 19

a solution in which water is the solvent

Question 20

hydration shell

Answer 20

the sphere of water molecules around a dissolved ion

Question 21

hydrophilic

Answer 21

having an affinity for water

Question 22

hydrophobic

Answer 22

having no affinity for water; tending to coalesce and form droplets in water

Question 23

molecular mass (molar mass)

Answer 23

the sum of the masses of the atoms in a molecule; sometimes called molecular weight

Question 24

mole (mol)

Answer 24

the number of grams of a substance that equals its molecular or atomic mass in daltons; a mole contains Avogadro’s number of the molecules or atoms in question

Question 25

molarity

Answer 25

a common measure of solute concentration, referring to the number of moles of solute per liter of solution

Question 26

hydrogen ion

Answer 26

a single proton with a charge of 1+. the dissociation of a water molecule (H2O) leads to the generation of a hydroxide ion (OH-) and a hydrogen ion (H+); in water, H+ is not found alone but associates with a water molecule to form a hydronium ion

Question 27

hydroxide ion (OH-)

Answer 27

a water molecule that has lost a proton; OH-

Question 28

hydronium ion

Answer 28

a water molecule that has an extra proton bound to it; H3O+, commonly represented as H+

Question 29

acid

Answer 29

a substance that increases the hydrogen ion concentration of a solution

Question 30

base

Answer 30

a substance that reduces the hydrogen ion concentration of a solution

Question 31

pH

Answer 31

a measure of hydrogen ion concentration equal to -log[H+] and ranging in value from 0 to 14

Question 32

buffer

Answer 32

a solution that contains a weak acid and its corresponding base. a buffer minimizes changes in pH when acids or bases are added to the solution

Question 33

ocean acidification

Answer 33

the process by which the pH of the ocean is lowered (made more acidic) when excess CO2 dissolves in seawater and forms carbonic acid (H2CO3)