DAT General Chemistry 2 Flashcards

Terms Definitions
S^2-
Sulfide
Fe2+
Ferrous
N^3-
Nitride
S orbitals
Spherically symmetrical
Reduction
Gain of Electrons
Oxidation
Loss of electrons
Condensation
Gas to liquid.
-ic
represents greater charge
-ous
represents lesser charge
Cathode of Electrolytic Cells
NEGATIVE
Calorimetry
Measures heat changes.

Heat (q) absorbed or released in a given process is calculated from the equation:

q = mc(delta)T

m = mass
c = specific heat
delta T = the change in temperature
Galvanic Cells
Spontaneous reactions occur.

Redox reaction occurring in a galvanic cell has a negative delta G and is therefore a SPONTANEOUS reaction.

Commonly used as batteries.
Pi Bond
When the orbitals are parallel.
Electrochemical Reactions
Include spontaneous reactions that produce electrical energy, and nonspontaneous reactions that use electrical energy to produce a chemical change. Both types always involve a transfer of electrons with conservation of charge and mass.
Electrolytic Cells
Nonspontaneous reactions occur.

Has a positive Delta G and is therefore NONSPONTANEOUS.
-ide
Monatomic elements are named by dropping ending of the name of element and adding -ide
Colligative Properties
Physical properties derived solely from the number of particles present, not the nature of those particles.
Sublimation
Solid to gas (e.g dry ice)
Raoult's Law
Vapor-Pressure Lowering

When solute B is added to pure solvent A, the vapor pressure of A above the solvent decreases.

If the vapor pressure of A above pure solvent A is designated P-(A) and the vapor pressure of A above the solution containing B is P(A), the vapor pressure decreases as follows:

Delta P = P-(A) - P(A)
Alkali Metals
Elements of Group IA

Possess properties of metals, yet densities lower than other metals.

Have one loosely bound electron in outermost, giving largest radius.
Periods
Rows

- 7 periods, representing the principal quantum numbers n = 1 to n =7, and each is filled sequentially.
Adiabatic?
"No heat change" Q=0 (Insulated) ∆E=W
Percent Yield
used to express the relationship between the actual yield and the theoretical yield.

% yield = (actual yield/theoretical yield) x 100%
Noble gases
Also called inert gases.

Found in Group VIII (Also group O)

Fairly nonreactive because complete octet.

Low bp and all are gases at RT.
Critical Point
Tip between liquid and gas phases.

Temperature and pressure above which no distinction between liquid and gas is possible.
Bond length
In reference to covalent bonds.

Average distance between two nuclei of atoms involved in the bond.

As number of electrons shared increases, the two atoms are pulled closer together, which decreases bond length.

Triple < Double < Single
Higher-order reactions
Has an order greater than 2.
Net Ionic Equations
Because reactions such as displacements often involve ions in solution, they can be written in ionic form.

Important for demonstrating the actual reaction. Shows only the species that actually participate in reaction (minus spectator ions)
Anion
Atom that gains electrons becomes a negatively charged ion.
Per-
When the series of oxyanions contain FOUR oxyanions, then prefixes used.

MORE oxygen = Per-
What is the maximum number of electrons that can be present in an atom with a principal quantum number of 5?
50
-ate
When an element forms two oxyanions, then name of the one with MORE oxygen ends in -ate.
Freezing-Point Depression
Delta T(f) = K(f)m

K(f) = proportionality constant characteristic of a particular solvent
m = molality of the solution (mol solute/kg solvent)

If compound is ionic, the formula for the freezing point depression has to be multiplied by the number of particles formed upon dissolving.
Polar molecule
Molecule with a net dipole moment.

Depends on the polarity of the constituent bonds and on the shape of the molecule.
-ite
When an element forms two oxyanions, then name of the one with LESS oxygen ends in -ite.
What are salts of nitrous acids called?
Nitrites
Triple Point
Intersection of the three lines is called triple point. At this temperature and pressure, unique for a given susbtance,....

All three phases are in equilibrium.
Molar Mass
Sometimes identity of gas is unknown, and molar mass must be determined.

Find weight of sample by volume to calculate the density. And MW is found by multiplying the number of grams per liter by 22.4 L per mole.
Anode of Electrolyic Cells
Positive

Since attached to the positive pole of the battery and so attracts anion from the solution.
A lewis acid, by definition
Accepts an electron pair
Ideal Gas Law
PV = nRT

Combines the relationships outlined in Boyle's law, Charles' Law, and Avogadro's Principle to yield an expression which can used to predict the behavior of a gas.
Neutrons
Neutrons carry no charge and have a mass slightly larger than that of protons.

Different isotopes of one element have different numbers of neutrons, but same number of protons.

Mass number = total number of protons and neutrons.
Measurement of pOH
pOH = -log[OH-] = log (1/[OH-])
Conjugate base
Formed when an acid loses a proton.

e.g. HCO3-/CO3^2- (conjugate acid/base pair)
Isolated system
When it cannot exchange energy or matter with the surroundings, as with an insulated bomb reactor.
Nonbonding Electrons
Valence electrons not involved in the covalent bond. (or lone electron pairs)
Mole
Defined as the amount of a substance that contains the same number of particles are found in a 12.000 g sample of carbon-12.

1 mole = 6.022 x 10^23 particles

mol = (weight of sample (g)) / (molar weight (g/mol))
What is the hybridization and bond angle of a molecule with 6 electron domains?
SP3D2, 90˚
First-order reactions
Order = 1
Has a rate proportional to the concentration of one reactant.

rate = k[A] or rate = k[B]

Units: sec-1
Formula Weight
Of an ionic compound is found by adding up atomic weights according to the empirical formula of the substance.
Reducing agent
Causes the other atom to be reduced, and is itself oxidized.
Roman Number above group
Represents the number of valence electrons.
Three ways to report Yield
1. Theoretical yield
2. Actual Yield
3. Percent Yield
Energy State
Is the position and energy of an electron described by its quantum numbers.
Heisenberg uncertainty principle
States that it is impossible to determine, with perfect accuracy, the momentum and position of an electron simultaneously.
A Sample of Argon occupies 50L at standard temperature. Assuming constant pressure, what volume will the gas occupy if the temperature is doubled?

a. 100L
b. 25L
c. 20L
d. 200L
e. none of the above
a. 100L
Density
Defined as mass per unit volume of a substance and, for gases is usually expressed in unites of g/L.

d = m/v = P(MM)/RT
Closed system
When it CAN exchange ENERGY, but NOT matter with the surroundings, as with a steam radiator
Le Chatelier's Principle
Used to determine the direction in which a reaction at equilibrium will proceed when subjected to stress, such as change in concentration, pressure, temperature, or volume.
Characteristic of Metals
Shiny solids (except mercury) at room temp., and generally have high melting points and densities.

Ability to be deformed without breaking (malleability and ductility)

large atomic radius, low ionization energy, and low electronegativity.

Good conductors of heat and electricity.

Groups IA and IIA (most reactive metals)

transition (metals with partially filled d orbitals)
Arrhenius Acid
Species that produces H+ (a proton) in an aqueous solution.
Density = ?
Mass/Volume, but given the grams - find the moles, then find out how much volume by the moles at STP. Ex) 2 moles = 44.4L
If enough water is added to 11g CaCl2 to make 100 mL of solution, what is the molarity of the solution?
1M
BaCO3(s) + HCl(aq) --> ?
Gas forming reaction.

Product is H2O + CO2 + BaCl2

Sum of coefficents is 6

Balanced net reaction:
BaCO3 + 2 H --> H2O + CO2 + Ba2+
What are the empirical and molecular formulas of a compound which contains 40.9% carbon, 4.58% hydrogen, 54.52% oxygen, and has a molecular weight of 264 g/mol?
Answer: Molecular C9H12O9
Empirical C3H4O3

Solution:

# mol C = [(0.409)(264)g] / 12 g/mol = 9 mol

# mol H = [(0.0458)(264)g] / 1 g/mol = 12 mol

# mol O = [(0.5452)(264)g] / 16 g/mol = 9 mol
Which molecule is soluble?

a. AgCl
b. PbCl2
c. HgBr2
d. HgCl2
e. none of the above
e. none of the above
Percent composition by mass
[Mass of solute/mass of the solution (solute + solvent)] x 100
First and Second Ionization Energies
First ionization energy is energy required to remove one valence electron, the second is energy needed to remove a second valence electron.

Successive ionization energies grow increasingly large.
Conjugate acid
Defined as the acid formed when a base gains a proton.
Reaction Quotient
Q, is the measure of the degree to which a reaction has gone to completion.

Qc = ([C]^c[D]^d) / ([A]^a[B]^b)

Is constant only at equilibrium, when it is equal to Kc.
1 m NaCl
1.5 m CH3OH
0.8 m AlCl3
1.2 m CsNO3
Which has highest/lowest boiling point?
Which has highest/lowest freezing point?
(i)(m)=
NaCl =2m
CH3OH =1.5m (Highest FP, Lowest BP)
AlCl3 =3.2m (Highest BP and Lowest FP)(Lowest Vapor Pressure)
CsNO3 =2.4m
Medium and Reaction Rates
Rate of a reaction may also be affected by the medium in which it takes place.

Certain reaction proceed more rapidly in aqueous solution.
Standard Temperature and Pressure
273.15 K (0 degrees Celsius) and 1 atm.
An atom is composed of...?
An atom is composed of subatomic particles called protons, neutrons, and electrons.
Law of Constant Composition
States that any sample of a given compound will contain the same elements in the identical mass ratio.

e.g every sample of H2O will contain two atoms of hydrogen for every atom of oxygen, or in other words, one gram of hydrogen for every eight grams of oxygen.
Alpha Decay
A = -4 and Z = -2

Emission of an alpha particle, which is a 4 He nucleus that consists of 2 protons and 2 neutrons.

alpha = 4/2 He
Molar weight or molar mass
Expressed as g/mol

e.g. molar mass of H2CO3 = 62 g/mol
Which of the following is an assumption of the kinetic molecular theory of gases?

a. particles have negligible volume
b. no intermolecular attraction
c. random motion, continuous movement of molecules
d. average kinetic energy of gas particles is proport
e. all of the above.
Which phase changes are "exothermic"?
Gas - Liquid - Solid = Crystallization, Condensation, Deposition
How many moles of water are produced in the combustrion of 20 g of glucose in excess O2?
Answer 2/3

Solution:
First, write out balanced equation:

C6H12O6 + 6 O2 --> 6 CO2 + 6 H2O

Now solve for moles of H2O:

20g glucose x (1mol/180g glucose) x (6 mol H2O/1 mol glucose) = 120/180 = 2/3
Rules for Constructing a Cell Diagram:
1. Reactants and products are always listed from left to right in the form:

anode - anode solution -- cathode solution - cathode

2. Single vertical line indicates phase boundary.

3. A double vertical line indicates the presence of a salt bridge or some other type of barrier.
N2(g) + 3 H2(g) -> 2NH3(g)
With 10 moles N2 and 20 moles H2
What is the Limiting Reagent and Theoretical Yield?
Limiting Reagent = H2
Theoretical Yield = 13.33 mol NH3
If 10g oh NaOH is dissolved in 500g of water, what is the molality of the solution?
1/2 or 0.5
Le Chatelier's Principle: Change in Concentration
Increasing [] of a species will tend to shift the equilibrium away from the species that is added, in order to reestablish its equilibrium [].
Le Chatelier's Principle: Changes in Pressure or Volume
In a system at constant temperature, a change in pressure causes a change in volume, and vice versa.

Change in pressure or volume in liquids/solids will have little or NO effect.

Reactions involving gases, however, may be greatly affected by changes in P or V, since they are highly compressible.

Pressure and volume are inversely related. Increase in pressure will decrease moles of gas present (decreasing volume).
Calculating pOH for weak base buffer solution
pOH = pKb + log ([conjugate acid]/[weak base])

When [conjugate acid] = [weak base], pOH = pKb
How do you find out the rate of effusion? Which gas escapes faster and by how much?
Rate1/Rate2 =√Molar mass2/ Molar mass1
Ex) Rate H2/Rate O2 = √32/2
If [H+] = 0.001, what is the pH?
0.001 = 10^-3, then pH = 3
Calculating pH for weak acid buffer solution
pH = pKa + log ([conjugate base][weak acid])

When [conjugate base] = [weak acid], pH = pKa
Why will the reaction NaOH + H2SO4 go to completion?
Because it is a neutralization reaction, where a strong acid reacts with a strong base to form salt and a water in a double displacement reaction
What is the percent yield if 78 g of C6H6 reacts and 82 g of C6H5NO2 is formed according to the reaction below?

C6H6 + HNO3 --> C6H5NO2 + H2O
Answer: 67%

Percent Yield = (Actual Yield/Theoretical Yield) x 100%

Actual Yield = 82 g
Theoretical Yield =
78g C6H6 x (1mol/78g C6H6) x (1mol C6H5NO2/1mol C6H6) x (123 g/mol C6H5NO2) = 123 g

% yield = 82/123 = 0.667 x 100 = 67%
What does Ksp have to do with solubility?
The larger the Ksp the more able to dissolve the molecule is.
If Ka = 1.8 x 10^-5, then what is pKa?
pKa = 5 - log 1.8.

Since 1.8 is small, its log will be small, and the answer will be closer to 5 than to 4. (The actual answer is 4.74)
If 28g of Fe react with 24 g of S to produce FeS, what wold be the limiting reagent? How many grams of excess reactant would be present in the vessel at the end of the reaction?

balanced eqn: Fe + S --> FeS
Answer: Fe is limiting reagent and 8 g of S will be in excess.

Solution:
First, the number of moles for each reactant must be determined.

28 g Fe x (1 mol Fe/56g) = 0.5 mol Fe

24 g S x (1 mol S/32g) = 0.75 mol

Fe is limiting.

Calculate excess:
mass of S = 0.25 mol S x (32 g/mol S) = 8 g of S
/ 94
Term:
Definition:
Definition:

Leave a Comment ({[ getComments().length ]})

Comments ({[ getComments().length ]})

{[comment.username]}

{[ comment.comment ]}

View All {[ getComments().length ]} Comments
Ask a homework question - tutors are online