Chemistry of life

Question 1

What identifies an element in the periodic table

Answer 1

The number of protons

Question 2

What is the atomic number?

Answer 2

he number of protons in an element.

Question 3

mass number?

Answer 3

The sum of the number of protons and neutrons in an atom.

Question 4

Atoms have volume and mass.
Mass of one proton or one neutron = 1
atomic mass unit (amu) or 1 dalton

Answer 4

1.7 × 10–24 grams.
Mass of one electron = 9 × 10–28 (usually
ignored).

Question 5

Element

Answer 5

pure substance containing
only one kind of atom.
Elements are arranged in the periodic
table.
Each element has a unique chemical
symbol.

Question 6

Mass number =

Answer 6

number of protons +
number of neutrons.
mass of atom in daltons

Question 7

Isotopes:

Answer 7

forms of an element with
different numbers of neutrons, and thus
different mass numbers

Question 8

Atomic Weight

Answer 8

average of mass
numbers of isotopes in their normally
occurring proportions.
Atomic weight of carbon = 12.011
Atomic weight of hydrogen = 1.0079

Question 9

What is the role of bicarbonate anion in blood?

Answer 9

It mops up excess acid, helping to buffer the blood

Question 10

What can carbonic acid be converted to?

Answer 10

Carbon dioxide (CO₂)

Question 11

What is a buffer

Answer 11

A weak acid/weak base system that resists changes in pH.

Question 12

What are the components of the buffer reaction shown?

Answer 12

H2O+CO2 ⇌H2CO3
​

H2CO3⇌H+ + HCO3−
​

Question 13

What happens when an acid is added to a buffer solution?

Answer 13

The buffer reacts to minimize changes in pH.

Question 14

What happens when a base is added to a buffer solution?

Answer 14

The buffer reacts to resist changes in pH.

Question 15

What does the law of mass action illustrate?

Answer 15

Addition of reactant on one side of a reversible equation drives the system in the direction that uses up that compound

Question 16

What happens to the reaction when an acid is added?

Answer 16

: It drives the reaction in one direction

Question 18

base

Answer 18

vice versa

Question 19

Why are buffers important for life?

Answer 19

They help maintain stable pH levels in biological systems

Question 20

What is the ionization of strong acids and bases?

Answer 20

irreversible

Question 21

How is the ionization of weak acids and bases characterized?

Answer 21

Somewhat reversible.

Question 22

What is the tendency of water regarding ionization

Answer 22

Water has a slight tendency to ionize.

Question 23

How many water molecules actually dissociate?

Answer 23

1 in 500 million water molecules

Question 24

ionization of water?

Answer 24

H2O⇌ H+ + OH −

Question 25

How does water behave in terms of acid-base chemistry?

Answer 25

: Water acts as both a weak acid and a weak base.

Question 26

ionization of water important for organisms?

Answer 26

Because of the abundance of water in living systems and the reactive nature of the
H
+

ions.

Question 27

pH?

Answer 27

pH
-Log10[H+]

Question 28

H
+
H
+
concentration of pure water?
A:
1
0
−
7
 
M
10
−7
M with a pH of 7.

Q: What does a lower pH number indicate?
A: A higher
H
+
H
+
concentration, or greater acidity.

Q: What is the
H
+
H
+
concentration and pH of a 1 M HCl solution?
A:
H
+
H
+
concentration = 1 M, pH = 0.

Q: What is the
H
+
H
+
concentration and pH of a 1 M NaOH solution?
A:
H
+
H
+
concentration =
1
0
−
14
 
M
10
−14
M, pH = 14.