Exam 3 blocks 7-9 Flashcards
1
Q
What does chemical arithmetic allow?
A
It allows us to us the information provided by balanced chemical equations to describe chemical reactions in two ways
Qualitative and quantatative
2
Q
What is formula mass?
A
the sum of all of the atomic masses of all atoms in its chemical formula
3
Q
What is the conversion factor for converting amu’s into grams
A
1.000amu=1.660x10^-24g
4
Q
What are the two ways that quantity of a sample can be expressed?
A
mass of a sample
number of objects in a sample
5
Q
How much is one mole of something?
Avogadro’s number
A
1 mole=6.02x10^23
6
Q
Is Avogadro’s number exact?
A
yes
7
Q
to find out how many atoms in a mole?
A
we multiply by Avo’s number
8
Q
To find out how many moles from a number of atoms?
A
We divide by Avo’s number
9
Q
What is Molar mass?
what is its abbreviation?
Unit expression?
A
The mass of one mole of an object
MM
Grams per mole, g/mole, g-mole^-1
10
Q
How do we find the molar mass of an element?
A
it is the same as the amu off the periodic table just expressed in grams
11
Q
How would we find the find the mass of a single atom of an element that is expressed in grams per mole?
A
we would divide the MM by Avo’s number
12
Q
How would we find out the mass of one mole of an element in amu’s?
A
multiply the amu by Avo’s number
13
Q
how do we convert formula mass to compound molar mass?
A
change the units from amu to g
no conversion required
14
Q
Why is it that we can switch from amu to g without a conversion?
A
The definition of a mole + the fact hat amu is baised off of C-12
15
Q
What is a Mole?
A
The amount of a substance in a system that contains as many elemental particles as there are atoms in exactly 12 grams of C-12
16
Q
What is the ever repeating core in chemical calculations?
A
Number of moles of the the substance times time the number of moles of the specific element in the substance over one more of the substance
example, How many moles of O in a 1.5 mole sample of CO2
2 Moles of O
1.5 moles of CO2 X —————— = 3.0 moles of O
1 Mole of CO2
17
Q
What is a chemical equation?
A
A written statement that uses symbols instead of words to describe the changes that occur as chemical reaction proceed
18
Q
What is (s) mean in a chemical equation?
A
solid
19
Q
What is (g) mean in a chemical equation?
A
gas
20
Q
What is (l) mean in a chemical equation?
A
dissolved in some liquid
21
Q
What is (aq) mean in a chemical equation?
A
dissolved in water
22
Q
What is stoichionmetry
A
Stoichiometry the application of the laws of definite proportions and the conservation of mass and energy to chemical activity
23
Q
What does the concept of mass balance require?
2 things
A
all atoms present as reactants MUST also be present as products
all atoms present as products MUST also be present as reactants
24
Q
The law of conservation of matter dictates…….
A
That mass balance must be observed in chemical reations
mass can neither be created or destroyed in ordinary chemical reactions and changes
reactants simply rearrange themselves into new substances (products) in chemical reactions
25
What is the chemical equation for the haber process?
| What is this process describing?
N2(g)+3H2(g)------> 2NH3(g)
| Nitrogen fixing makes N2 bio-available
26
What is the balanced equation for the thermite reaction?
2Al(s)+Fe2O3(s)----->2Fe(s)+Al2O3(s)
27
Secondary forces aka...
intermolecular forces
28
where do secondary intermolecular forces occur?
between function between the fundamental particles within a system
29
The prefix Inter means?
between
30
What substance has a total absence of intermolecular forces?
ideal gasses
31
Intermolecular forces are dominate in ___
solids
32
intermolecular forces are nonexistent in ____
ideal gasses
33
Inter and intra-molecular forces are equal in_____
liquids
34
What is the formula for kinetic energy?
KE=1/2mXv^2
35
What does KMTM stand for?
The Kinetic Molecular Theory of Matter
36
What is the KMTM
5 statements Based on the fact that all fundamental particles in a system are always in motion regardless of their physical state
37
What is the first statement of the KMTM
Fundamental particles that compose matter have definite and characteristic sizes
38
What is the second statement of the KMTM
The fundamental particles in any system possess a certain amount of kinetic energy in the form of constant random motion.
39
Why is kinetic energy considered a disruptive force in matter?
The random constant motion of the fundamental particles cause them to move further and further apart from one another decreasing the stability of the system. Weakening the matter.
40
What is the third statement of the KMTM
The atoms and molecules in any syatem also possess certain amount of potential energy stored in two possible forms
intramolecular force stored in chemical bonds
in covalent bonds PE is present in intermolecular forces as well *much weaker
41
Why is potential energy considered a cohesive force.
Potential energy pulls particles in a system closer together and increases the stability of the system
42
Where does the potential energy come from?
Electrostatic interactions
43
Where can PE be found in ionic compounds?
only in intramolecular forces of covalent compounds have PE
44
Where can PE be found in covalent compounds?
IN both the inter and intra-molecular forces
45
What is the fourth statement of the KMTM?
The velocity of the particles in a system is temperature dependent
The higher the temp the faster the particles move the more KE produced
46
What is the fifth statement of the KMTM?
As particles in the system collide with eachother via "elastic collisions" they will transfer KE between themselves.
47
What are elastic collisions?
Hypothetical collisions in a system where energy is conserved within a system
48
particles in a system refereed to as hot have ____ KE
higher
49
particles in a system refereed to as cold have ____ KE
lower
50
What is the overall statement of the KMTM?
to explain the differences in states of matter in terms of the disruptive(KE) and cohesive(PE) forces present
51
When does kinetic energy equal 0?
never even the most solid matter will have some KE
52
When doe PE equal 0?
only in ideal gasses
53
What is an ideal gas?
a hypothetical gas in which cohesive forces are nonexistent. all collisions are elastic
54
What gasses can be considered idea?
Virtually all of them.
| Because at room temp. the cohesive forces as so close to 0 they can be taken out of the equation
55
Reducing temperature reduces ___energy
kinetic
56
increasing temperature increases _____energy
Kinetic
57
When will ideal gasses show "real" behavior?
if intermolecular forces are allowed to form...AKA temperature reduction or a pressure increase leads to increased intermolecular cohesive forces
58
A gas is compressed when....
the size of its container is decreased but the number of gas particles is not.
59
pressure increase from compression occurs because?
the particles have more frequent collisions with the sides of the container
60
What are three ways to increase pressure?
Compression, Temperature increase, and adding more gas to the same container
61
pressure =?
the number of collisions with container
62
What are gas laws?
mathematical expressions that describe the relationships between variables in gasses
63
What are the 4 variables in gas laws?
#of moles (n)
Pressure (P)
Volume (V)
Temperature (T)
64
What does the subscript "1" mean in a gas law?
starting condition
65
What does the subscript "2" mean in a gas law?
ending condition
66
What is Boyles law and what does it state?
An inverse pressure-volume relationship
states that the pressure of a gas is inversely proportional to the volume occupied by the gas when the number of moles and temperature are constant
67
What is boyles law equation?
P1xV1=P2xV2
68
What is charles law and what does it state?
A temp-volume direct relationship
states that the temp of a gas is directly proportional to the volume it occupies when moles and pressure are the same
69
What is charles law equation?
T2xV1= T1xV2
70
What is the combined gas law?
| When is it used?
a simple mathematical combination of boyles and charles law in which temp nor pressure need to be held constant
When volume, temp, and pressure are all changing
71
What unit does the temp. in the combined gas law need to be in?
K
72
What is the ideal gas equation?
| what two conditions need to be met to use it?
you are working with only one constant set of P,V,T conditions
the number of Moles(n) is changing
73
What units does T need to be in for the ideal gas law equation?
Kelvin
74
What units does P need to be in for the ideal gas law equation?
Atmospheres
75
What units does V need to be in for the ideal gas law equation?
Liters
76
What units does n need to be in for the ideal gas law equation?
moles
77
What is the R variable in the ideal gas law
the universal gas constant.
R= 0.0821 L x atm x mol^-1 x K^-1
78
How many in. Hg is in one atm?
1.000 amt=29.92 in
79
how many mm Hg in one atm
1.000 amt=760.0mm
80
How many torr in one atm?
1.000 amt=760.0 torr
81
how many PSI in one atm
1.00 amt= 14.7 PSI
82
How many bars in one atm
1.00 atm = 1.01 bar
83
What is the substitution for n in the ideal gas equation?
g
n=--------
mm
84
In chemistry what does STP stand for?
standard temp and pressure
0 degrees C and 1 atm pressure
85
In chemistry what does RTP stand for?
Room tempature and pressure
25 degrees C and 1 atm pressure
86
What is the standard molar volume of any ideal gas at STP?
22.4 L
87
what are intermolecular(secondary) forces
forces that occur between fundamental particles
88
what are intramolecular(primary) forces?
forces that occur within fundamental particles (chemical bonds) and are much stronger than intermolecular forces
89
in what state of matter do intermolecular forces have the largest effect? and why?
bother inter and intra forces are significant in liquids.
| only in liquids do the intermolecular forces cause dramatic effects.
90
how do intermolecular forces have an effect on the behavior of matter if they are so weak?
because they may be weak but they are additive throughout the system
91
What are the three intermolecular forces in liquids? list in order of strongest to weakest retaliative to single interactions
Hydrogen bonds
dipole-dipole
London forces
92
What is a Dipole-dipole interaction?
and electrostatic attraction between polar molecules
93
how is the boiling point of a liquid affected by the presence of dipole dipole interactions?
the boiling point is increased by the presence of dipole dipole interactions as they increase the cohesive forces within the liquid because the collective attraction of the forces increase the strength and stability of the liquid
94
What is hydrogen bonding?
an extremely strong dipole dipole interaction
95
is a hydrogen bond a type of chemical bond?
| why/why not?
No
| because it occurs between fundamental particles and it is nowhere near as strong
96
What are the only elements that can be involved in H bonding?
why?
F H O N
they are small and highly electronegative appart from H
97
What are the two criteria for H Bonding?
1- one of the members of the bond must be a hydrogen atom contently bonded to a very small AND highly electronegative atom (F, O, N)
2-the other member of the bond must be a small AND highly electronegative atom that also has a lone pair of electrons
98
Why is H bonding so important for life?
it is extremely significant in aqueous systems. and all life as we know it is aqueous
99
Explain the process of H bonding
Hydrogen contently bonds with either F, O, N.
The extreme difference in electronegativity causes hydrogen's sole electron to become so attracted to the electronegative atom that the hydrogen's nucleus becomes almost bare
the "bare" nucleus becomes attracted to the lone pair of the other molecule an is small enough to come very close to it. increasing the strength of the attraction
100
What is the other word for london forces?
van der Waals forces
101
what are london forces?
the weakest of all intermolecular forces, london forces which can occur in all covalent systems.
they are forces formed by the movement of electrons.
102
Explain london forces
electrons in a covalent system can be anywhere in the electron cloud at any given time. when the electrons (even for an instant) leave the favorable center of the bond they form an instantaneous dipole
103
what is an instantaneous dipole
when a bond becomes polarized due to the electrons in the bond leaving the favorable position in a covalent bond.
happens near the speed of light
104
what happens to adjacent molecules when london forces occur?
they all respond by either attracting or repelling the charge
the single formation of a dipole cause a chain reaction so that all other molecules in the system must react as well.
105
what does it mean for london forces to be transitory?
they switch on and off
106
what is evaporation?
a process in which molecules escape from the liquid phase and enter the gas phase
107
what are vapor molecules?
evaporated molecules
108
what are the three criteria for evaporation?
1-the molecules kinetic energy must be stronger than the cohesive forces
2-the molecules movement must be favorable for escape
3-the molecule must be close to the surface
109
what effects the rate of evaporation?
the exposed surface area
| the temperature
110
what are the two type of equilibrium?
static and dynamic
111
what are the effects of evaporation on the liquid phase?
volume decrease
| tempature decrease
112
define dynamic equilibrium
a condition which two processes which are exact opposites of each other are occurring at exactly equal rates so the net charge of the system equals zero
113
what is an example of dynamic equilibrium?
| explain
evaporation in a sealed container
as the molecules vaporize and fill the head space, it becomes more and more crowded. the collision of the vapor molecules in the head space cause some of them to loose enough kinetic energy to be below the level needed to escape in the first place. as random moments occur, once the molecule with low kinetic energy touches the surface of the liquid it condolences back into the liquid
114
what do dynamic equilibrium systems appear static
because everything is changing at equal rates
115
how are vapor pressure and evaporation related?
if the vapor pressure of a liquid is greater than the attm the liquid will evaporate
116
what makes a liquid volatile?
high vapor pressure
117
what is boiling point in terms of pressure?
when the vapor pressure is they same as the attm pressure the liquid will boil
118
where does the change of state occur in boiling liquids?
inside the bubbles that are formed
119
why does the temperature of a boiling liquid stay constant regardless of how much heat is applied?
because the bubbles formed when boiling develop a dynamic equilibrium
the heat lost in evaporation is equal to the amount of heat the liquid gains through condensation
120
the charge of ferric
III
| iron III
121
the charge of ferrious
II
| iron II
122
the charge of Cupric
II
| copper II
123
the charge of cuprous
I
| copper I
124
cobaltic
III
| cobalt III
125
cobaltous
II
| cobalt II
126
stannic
IV
| tin IV
127
stannous
II
| tin II
128
plumbic
IV
| Lead IV
129
plumbous
II
| lead II
