Midterm 2: Water

Question 1

What percent of the body is composed of water?

Answer 1

the human body is 60-70% water

Question 2

What is the most abundant component of every cell?

Answer 2

water

Question 3

How many electrons does oxygen have in its outer shell that can be involved in chemical bonds?

Answer 3

6 electrons

Question 4

How many valence electrons from oxygen form a chemical bond with each hydrogen atom in water?

Answer 4

2 valence electron; 4 are unshared

Question 5

What type of bonds form between hydrogen and oxygen?

Answer 5

polar covalent bonds

Question 6

a chemical bond formed between atoms by the sharing of electrons

Answer 6

Covalent bond

Question 7

electrons are shared unequally

Answer 7

Polar Covalent bond

Question 8

a stronger attraction for the electrons

Answer 8

MORE electronegative

Question 9

The more electronegative atom has a partial ______ charge.

Answer 9

negative charge (δ-)

Question 10

The less electronegative atom has a partial ______ charge.

Answer 10

positive charge (δ+)

Question 11

electrons are shared equally

Answer 11

Nonpolar Covalent bond

Question 12

Describe the electronegativities of the 2 atoms in a nonpolar covalent bond.

Answer 12

Electronegativities of the 2 atoms are equal

Question 13

What is a polar molecule?

Answer 13

have polar bonds

Question 14

The polarity of water enables it to form what type of bonds?

Answer 14

hydrogen bonds

Question 15

What is a hydrogen bond?

Answer 15

electrostatic attraction that occurs when 2 electronegative atoms interact with a hydrogen

Question 16

Describe the strength of hydrogen bonds and how they can increase strength.

Answer 16

Individual hydrogen bonds are weak, but in large #s, provide considerable strength

Question 17

(T/F) water is NOT a solvent

Answer 17

False

Question 18

What dissolved readily in water?

Answer 18

Ions and polar molecules

Question 19

What is an ion?

Answer 19

an atom or molecule with a net electric charge due to the loss or gain of one or more electrons

Question 20

Cation

Answer 20

loss of electron(s); positive charge

Question 21

Anion

Answer 21

gain of electron(s); negative charge

Question 22

Polar Molecule

Answer 22

a molecule with an unequal distribution of electrons across the molecule (One part of the molecule has a partial negative charge (δ-) and the other a partial positive charge (δ+))

Question 23

Nonpolar molecules are not electrostatically attracted to water (T/F)

Answer 23

TRUE

Question 24

The concentration of hydrogen ions produced by dissociation in pure water is

Answer 24

1 x 10-7 M

Question 25

__________is moles of a solute per liter of solution (mol/L).

Answer 25

M (molarity)

Question 26

1 mole equals _______ particles of that substance.

Answer 26

6.02 x10^23 particles

Question 27

Solutions are classified as acidic or basic based on their ______________ relative to pure water.

Answer 27

hydrogen ion concentration

Question 28

_______ solutions have a higher [H+] than water

Answer 28

acidic

Question 29

_______ solutions have a lower [H+] than water

Answer 29

basic (alkaline)

Question 30

A base added to an aqueous solution _________ [H+] by binding H+.

Answer 30

Decreases

Question 31

An acid added to an aqueous solution _________ the [H+] by donating H+

Answer 31

Increases

Question 32

Strong acids and bases completely dissociate in water (T/F)

Answer 32

TRUE

Question 33

Weak acids and bases completely dissociate in water (T/F)

Answer 33

FALSE

Question 34

Weak acids and weak bases can act as _____ in solutions.

Answer 34

Buffers

Question 35

Buffers resist __________when small quantities of acid or base are added to the solution

Answer 35

changes in PH

Question 36

Buffers can both bind or release protons and, in doing so, prevent ________________________.

Answer 36

the pH from changing rapidly.