flashcards
1
Q
What is chemistry?
A
study of electrons, atoms and molecules that make up matter and the changes they undergo during some process
2
Q
adding sig figs
A
stay the same exponent
3
Q
multiplying sig figs
A
adding the exponents
4
Q
how many sig figs in 0.31
A
2
5
Q
sig figs in 12.0
A
3
6
Q
in 0.310
A
3
7
Q
sig figs in addition
A
lowest amount after decimal
8
Q
multiplication/division
A
least amount of sig figs
9
Q
converting between units
A
amount * (how much/in one unit)
2.46$ to pennies
2.46 * (100 pennies/1dollar) = 246
10
Q
how much is 1 kg in g
A
1000
11
Q
how much is 1 L in cm^3
A
1000 cm^3
12
Q
law of conservation of mass
A
matter isn’t created or destroyed
13
Q
dalton’s atomic theory (4):
A
1) all matter is made up of small, indivisible particles called atoms
2) atoms in same element have same mass (diff elements, diff properties)
3) atoms of diff elements combine in simple whole number ratios
4) chemical reactions result in separation, combination or rearrangement of atoms
14
Q
dalton definition
A
atoms are small and indivisible
15
Q
mass # = ?
A
a # protons + # neutrons
16
Q
atomic # = ?
A
a # protons
17
Q
isotopes
A
atoms having same # protons but diff # neutrons
18
Q
atomic mass units (amu)?
A
masses of atoms = mass #
19
Q
mass # ?
A
average of isotopic masses
20
Q
molecular formula
A
exact # and ratio of each element
(H2O)
21
Q
structural formula
A
how atoms are bonded together
(H-O-H)
22
Q
empirical formula
A
simplest whole # ratio (H2O2 = HO)
23
Q
avogadros number
A
6.022 x 10^23 = 1 mole
24
Q
molar mass
A
mass in grams of 1 mole = mass #
25
molecular mass
average mass (amu)
26
molecular formula
some multiple of empirical formula
27
chemical reaction
process in which a substance is changed into one or more new substances
28
stoichiometry
study of quantitative aspects of chemical recations
29
what does the quantity of product formed from a reaction depend on?
amount of reactant available
30
limiting reagent
consumed reagent
31
excess reagent
leftover reagent
32
limiting reagent is the
substance is is not enough to consume other reactant
33
molarity (M)
moles solute/litres solution
34
Molality (m)
moles solute/kg solvent
35
mole fraction (Xa)
moles/ (moles a + moles b + moles c)
36
weight percent
(g solute/g solution) x 100%
37
what are the 2 methods to prepare solutions of a specific concentration?
1 - weight out a solid solute and dissolve in a given quantity of solvent
2 - dilute a concentrated solution to give one that is less concentrated
38
preparing solutions by dilution shortcut?
(Mi)(Vi)=(Mf)(Vf)
39
what are 3 characteristics of gases
1 - uniformly fill any container
2 - mix with any other gas
3 - exert pressure on its surroundings
40
pressure =
force/area (units of Pa = N/m^2)
41
1 atm = ?
101.325 kPa = 760 mm Hg
42
manometers?
finding pressure of enclosed gas
43
ideal gas law
pV=nRT (is emprirical)
44
gas density
d = (p(MM))/(RT)
45
for mixture if gases, overall pressure??
sum of all partial pressures (p1 + p2 + p3)
46
what is kinetic molecular theory?
theoretical model to explain macroscopic behaviours based on microscopic properties of atoms and molecules in gas
47
what are the assumptions of KMT?
1 - gas molecules are in straight line constant motion
2 - volume of individual particles is 0
3 - collisions cause pressure exerted by gas
4 - particles don't attract to repel each other except during collisions
5 - average KE is proportional to temp of gas (K)
48
pressure exerted is proportional to?
1 - momentum w/ which gas particles hit the wall (momentum = mv)
2 - rate of collisions w/ the wall
49
p =
= = (Nmv^2)/V
50
3d p =?
= = (Nmv^2)/3V
51
KE = ?
(1/2)(mv^2)
52
particles travel faster...?
when they are light and at higher temperatures
53
diffusion
gradual mixing of molecules of diff gases
54
effusion
escape of gas from its container thru a small hole
55
graham's law
(RateA)/(RateB)= sqrt(MMb/MMa)
56
do real molecules have volume
yes
57
gases will exhibit behaviour closest to ideal behaviour at?
high temperatures and low pressures
58
thermochemistry
energy changes involved in chemical reactions
59
energy
capacity to do wrok or to produce heat
60
potential energy
= energy available to a system due to the position of system
61
kinetic energy
energy available due to motion on object
62
1st law of thermodynamics
total energy of universe is constant
63
state function =
property of a system that can be defined by current state system (independent of pathway)
64
what are examples of state functions
energy, pressure, volume and temperature
65
universe =
system + surroundings
66
when is change in energy positive?
when energy flows into system
67
when is change in energy negative?
when energy flows out of system
68
internal change
sum of KE and PE
69
change in internal energy =
sum of heat produced/consumed by system and work done on or by the system (U = q + w)
70
heat =
flow of thermal energy between susbatnace that are at diff temps (ttansfer of energy between 2 objects)
71
work
movement against a force = f x d
72
when is heat positive? negative?
+ = absorbed by system
- = absorbed by surroundings
73
when is work pos? neg?
+ = work done on system
- = work done by system
74
1 cal =
4.184 J
75
temperature
property that reflects motions of particles in substance
76
heat capacity (C) =
heat energy required to raise the temp of a given quantity of substance by a given temperature
77
specific heat capacity =
heat absorbed/mass
78
molar heat capacity =
heat absorbed/moles
79
work done by a gas
expansion
80
work done to a gas
compression
81
w =
p(change in V)
- pressure is external pressure = positive
- change in V is pos = volume is inc
- w is negative = work done by system
System = -p(change in v)
82
what drives chemical reactions
thermodynamics and kinetics
83
enthalpy of reaction =
heat given off or absorbed by a reaction at constant pressure (change in H)
84
endothermic
heat flows into system
85
exothermic
heat flows out of system
86
reversing a chemical equation will reverse sign of enthalpy for reaction
true
87
heat of solution?
heat generated/absorbed when a certain amount of solute dissolves in a certain amount of solvent
88
reversible reaction is in equilibrium when (3)
1 - rates of forward and reverse reaction are equal
2 - the conc of reactants and products remain constant (but not equal to each other)
3 - molecules are in constant motion (dynamic)
REMEMBER NOT ALL REVERSIBLE REACTIONS ARE IN A STATE OF EQUILIBRIUM
89
what is constant?
ratio of products to reactants raised as an exponent (K = products/reactants)
90
Kp (pressures in atm)
gas-phase reactions
91
Kc
solution reactions
92
Ka
acid appears on left of reaction
93
Kb
base appears on left of reaction
94
Ksp
solid compound dissolves
95
gases drive equilibria more than liquids or solids
true
96
reversing = reciprocal of value of K
true
97
multiplying coefficient by variables = multiply the equilibrium const to the corresponding power
true
98
overall reaction is sum of 2 reactions
true
99
sum of 2 more reactions = equilibrium const is product
true
100
le chartaliers principle
in external stress is applied to a system at equilibrium, the system adjusts in such a way that the stress is partially offset as the system reaches a new equilibrium
101
external stress?
conc, temp, pressure/volume for gases
102
reaction will shift away from added component to consume that component
true
103
for gases which side will the side shift too? (pressure is inc)
side that decreases the number of moles of gas until equilibrium is established
104
for gases which side will the side shift too? (pressure is dec)
side that increases the number of moles of gas until equilibrium is established
105
as volume inc, what happens to pressure?
decrease
106
why does temperature change and cause change in K?
because to consume any added heat
107
If T inc... (endothermic)
K increases
108
If T inc... (exothermic)
K decreases
109
Arrhenius acids?
substances ionize in water to produce H+ ions
110
arrhenius base?
substances that ionize in water to produce OH- ions
111
bronsted acid
proton donor
112
bronsted base
proton acceptor
113
strong acids are... what in water?
completely ionized because they are strong electrolytes
114
monoprotic acids
acids that have one ionizable proton
115
diprotic acids
acids that has 2 protons that can be donated pr the formula
116
polyprotic acid
acid that has more than 2 protons that can be donated per formula
117
metal hydroxides are?
strong bases
NaOH = Na+ + OH-
118
conjugate base
species that remains after a bronzed acid has lost its proton
119
conjugate acid
protonated species that is formed after a bronsted base gains a proton
120
how do conjugate acid/base pairs differ?
molecular formulas only differ by one proton
121
in aqueous solutions containing acids... water acts as a
base
122
in aqueous solutions containing bases... water acts as a
acid
123
autoionization
pure water will ionize to a small extent
124
pH =
pH = -log[H3O+]
125
pOH =
-log[OH-]
126
do stronger bases have large or small Kb
large
127
do weaker bases have large or small Kb
small
128
CH3OO- (aq) + H2O (l) = OH- (aq) + CH3COOH
yes
129
Hydrolysis
reaction of the cation or anion of a salt with water to produce a change in the pH of solution
130
which ones don't undergo hydrolysis
group 1 and 2 metal
if an anion is conjugate base of a strong acid
if anion is the conjure base of a weak acid
if cation is the conjug acid of a weak base
131
common ion effect
shift in equilibrium caused by addition of a compound having an ion in common w/ the dissolved substanvce
132
buffer solution
relatively large concentrations of a weka acid and conjugate base or a weak base and its conjugate acid (resist changes in pH)
133
molar solubility =
the max number of moles of solute that can be dissolved in a given volume of solvent at a specific temperatire (Ksp)
134
solubility
max mass of solute that can be dissolved in a given volume of solvent at a specific temp
135
saturated
Q = Ksp
136
unsaturated
Q < Ksp
137
superstaurated
Q > Ksp
138
how to decrease solubility of a salt?
adding a common ion
139
kinetics
how fast does a reaction proceed
140
Cr
4s13d5
141
Cu
4s13d10
