DAT General Chemistry Flashcards

Terms Definitions
Units of Current

∆P=0 (Same Pressure)
What is Osmotic Pressure=?
Or melting, solid to liquid.

Temperature at which this occurs is melting point.
Elements of Group VIIA

Highly reactive nonmetals with seven valence electrons.

Highly variable in properties.
Applications of Stoichiometry
1. Limiting Reactant
2. Yields
Temperature of the system reamins constant.
Split larger nucleus into smaller nuclei
Interaction between solute and solvent molecules.
Regions of space around the nucleus.

An orbital is a representation of the probability of finding an electron within a given region.
Rydberg constant
Experimentally determined constant = 2.18 x 10^-18 J/electron.
Materials that have NO unpaired electrons and are slightly repelled by a magnetic field.
Bond Energy
In reference to Covalent bonds.

Required to separate two bonded atoms.

Strength of bond increases as the number of shared electrons pairs increases.

Triple > Double > Single
Molar Mass = ?
Grams / moles
∆T=0 (Same Temperature) so ∆E=0, Q=-W
Three Different Forms of Matter
Gas, liquid, Solid
Atom that loses electrons become a positively charged ion.
Transition elements
Elements of Groups IB to VIIIB

Considered metals.

Hard and have high melting points and boiling points.

Moving across period, the give d orbitals become progressively more filled.
Nonrepresentative elements
B elements, including the transition elements, which have partly filled d sublevels.
Anode of Galvanic Cell

Because the spontaneous oxidation reaction that takes place at the galvanic cell's anode.
Resonance Structures
Two or more nonidentical Lewis Structures. Molecule exists as composite of the resonance structures.

- Lewis structure with small or no formal charges is preferred over large formal charges.

- Lewis structure in which negative formal charges are placed on more electronegative is more stable than when placed on less E.
Hydrogen Bonding
Specific, unusually strong form of dipole-dipole interaction, which may be either intra- or intermolecular.

Substances with hydrogen bonding tend to have high boiling points.

Important in behavior of water, alcohols, amines, and carboxylic acids.
Carry a single positive charge and have a mass approximately one atomic mass unit or amu.

The atomic number (Z) of an element is equal to the number of protons found in an atom. All atoms of a given element have the same atomic number.
Dispersion Forces
Short lived dipoles. Also called London forces.

Generally weaker than other intramolecular forces.

Do not extend over long distances and therefore most important when molecules are close together.
Hess' Law
States that enthalpies of reactions are additive.
Form of energy which can easily transfer to or from a system, the result of a temperature difference between the system and its surroundings.

Heat can be endothermic (asborbed) or exothermic (released).

Measured in calories (cal), or Joules (J), and more commonly in kcal or kJ.
Valence Electrons
Electrons farthest from the nucleus. Farther they are from nucleus = the weaker the attractive force the positively charged nucleus and more likely these electrons are influenced by other atoms.

Generally, these electrons determine the reactivity of an atom.
Protons and neutrons from nucleus. It is the core of the atom.
Same number of protons, but DIFFERENT number of NEUTRONS. (i.e. different mass numbers)
How do you measure the heat change?
Ionic bonding
Electrons from an atom with smaller ionization energy is transferred to an atom with a greater electron affinity, and the resulting ions are held together by electrostatic forces. (Transfer of electrons from less to more) - difference needs to be greater than 1.7
Heats of Combustion
Delta h(comb).

Reaction is often fast and spontaneous.
Osmotic Pressure
Substances tend to diffuse from higher to lower concentrations.


M = molarity
R = ideal gas constant
T = Temperature in Kelvin
Exponential Decay
Delta n / Delta t = -wavelength(n)

wavelength = decay constant
n = number that reamin
t = time
Conjugate acid-base pairs
Bronsted-Lowry acids and bases always occur in pairs.

The two members of a conjugate pair are related by the transfer of a proton.

e.g. H3O+ is conjugate acid of the base H2O
Freezing-Point Depression
Pure water freezes at 0 degrees Celsius.

Formula for calculating freezing-point depression:

Delta Tf = K(f)m

Delta Tf = freezing point depression

K(f) = proportionality constant

m = molality of the solution (mol solute/kg solvent)
Equivalence point
When number of acid equivalents equals the number of base equivalents added, or vice versa.
Excess reactant
Reactant that remains after all the limiting reactant is used up.
Limiting reactant
First reactant to be consumed. It limits the amount of product that can be formed in the reaction.
Types of Intermolecular Forces
Are attractive forces between molecules.

1. dipole-dipole interactions
2. hydrogen bonding
3. dispersion forces

dipole-dipole and dispersion are often referred to as van der waals forces.
Lewis Structure
Used to represent the bonding and nonbonding electrons in a molecule, facilitating "bookkeeping".
Ionic Compounds
Have high melting and boiling points due to strong electrostatic forces.
What is the hybridization and bond angle of a molecule with 3 electron domains?
SP2, 120˚
What is the molecular geometry of a molecule with 2 electron domains?
Second-order reactions
Order = 2
Has a rate proportional to the product of the concentration of two reactants, or to the square of the concentration of a single reactant.

e.g. rate = k[A]^2, rate = k[B]^2, or rate = k[A][B]

Units = M-1sec-1
Assigning Oxidation Numbers
1. The oxidation number of free elements is ZERO. (e.g. N2, P4, S8.)

2. Oxidation number for a monatomic ion is EQUAL to the charge of the ion. (e.g. Na+, Cu2+, Fe3+, Cl-, and N3- are +1, +2, +3, -1, and -3, respectively)

3. The oxidation number of each Group IA element in a compound is +1. The oxidation number of each Group IIA element in a compound is +2.

4. The oxidation number of each Group VIIA element in a compound is -1, except when combined with an element of higher electronegativity. (e.g. HCl, the oxidation number of Cl- is -1; in HOCl, however, the oxidation number of Cl is +1).

5. The oxidation number of hydrogen is -1 in compounds with less electronegative elements than hydrogen (Groups IA and IIA). (e.g. NaH and CaH2. The more common oxidation number of hydrogen is +1)

6. In most compounds, the oxidation number of oxygen is -2. This is not the case, however, in OF2. Here, because F is more electronegative, the oxidation number of O is +2. Also, peroxides such as BaO2, the oxidation number of O is -1.

7. The sum of the oxidation numbers of all atoms present in a neutral compound is zero. The sum of the oxidation numbers of the atoms present in a polyatomic ion is equal to the charge of the ion. Thus, for SO4^2-, the sum of the oxidation numbers must be -2.
- Delta (H) = ?
Exothermic = heat given off
Electrolytic cells differ from galvanic cells in that they....
Electrolytic cells are NONSPONTANEOUS and contain the anode and cathode in the same solution.

GALVANIC cells are SPONTANEOUS and half-reactions take place in SEPARATE containers.
Weak Acids and Bases
Those that partially dissociate in aqueous solution.

Weak monoprotic acid, HA, in aqueous solution will achieve the following eqn:

HA + H2O --> H3O + A
In electron capture, the atomic number (Z)...
Decreases by one
Open System
When it can exchange BOTH matter and energy with the surroundings, as with a boiling pot of water.
Electron Motive Force (EMF)
Difference in potential between two half cells. Adding reduction potential of the reduced to the oxidation.

EMF = E(red) + E(ox)

standard EMF for galvanic cell is POSITIVE

standard for electrolytic is NEGATIVE

Higher E (reduction potential) = reduced

Lower E = oxidized
Triple point
All three phase are in equilibrium at this T and P. And is where all three phases are present at the same time.
Spin Quantum Number
- Fourth quantum number.
- Denoted by m(s)
- Two spin orientations are designated +(1/2) and -(1/2).
- Whenever two electrons are in the same orbital, they must have opposite spins.
- Electrons in different orbitals with same m(s) values have parallel spins.
Types of Covalent Bonding
1. Polar Covalent Bond
2. Nonpolar Covalent Bond
3. Coordinate Covalent Bond
Mole Fraction =?
Mole Fraction = mol solute/ total moles
Characteristics of Covalent Bonds
1. Electrons are shared between the elements.
2. Elements bonded together are usually two nonmetals.
Subshell fill chart
1s (start here and zig zag)

4s 3d
5s 4d
5p 4f
6s 5d
6p 5f
7s 6d
7p (ends here)
(n + l) rule
Used to rank the subshells by increasing energy. Rule states that the lower values of the first and second quantum numbers, the lower the energy of the subshell.

Subshell with lower value will fill first.
Spectator ions
Ions that do not take part in the overall reaction but simply remain in solution throughout.
Buffer Solution
Consists of a mixture of a weak acid and its salt (which consists of its conjugate base and a cation), or a mixture of a weak base and its salt (which consists of its conjugate acid and an anion).
Atomic Number (Z)
Is equal to the number of protons found in an atom of that element.

All atoms of a given element have same atomic number.
Define specific gravity?
The ratio of density of a substance in any units to the density of water in the same units.
A zero order reaction has teh form

a. r = 0
b. r = k[A]
c. r = k[A][B]
d. r = [A]^0
e. r = k
e. r = k
Properties of equilibrium constant
1. Pure solids and liquids do NOT appear in the equilibrium constant expression.
2. Keq is characteristic of a given system at a given temperature.
3. If the value of Keq is very large compared to 1, an equilibrium mixture of reactants and products will contain very little of the reactants compared to products.
4. If it is very small compared to 1, it will contain very little product compared to reactant.
5. If Keq is close to 1, it will contain same amount of products and reactants.
Boyle's Law
PV = k or P1V1 = P2V2

Volume of gas is proportional to its pressure.
Single Displacement Reactions
Occurs when an atom (or ion) of one compound is replaced by an atom of another element.

e.g. Zn + CuSO4 --> Cu + ZnSO4
Balance this redox reaction:

MnO4^- + I^- --> I2 + Mn^2+
Step 1. Separate the two half-reactions:

I^- --> I2

MnO4^- --> Mn^2+

Step 2. Balance the atoms of each half reaction. First, balance all atoms except H and O. next, in an acidic solutiono, add H2O to balance the O atoms and then add H+ to balance the H+ atoms. (In a basic solution, use OH- and H2O to balance the O and H).

To balance the iodine atoms, place a coefficient of two before the I^- ion.

2 I^- --> I2

For the permanganate half-reaction, Mn is already balanced. Next, balance the oxygens by adding 4H2O to the right side.

Finally, add H+ to the left side to balance the 4 H2Os. These two half-reactions are now balanced.

MnO4^- + 8 H+ --> Mn^2 + 4 H2O

Step 3. Balance the charges for each half reaction. The reduction half must consume the same number of electrons as are supplied by the oxidation half. For the oxidation reaction, add 2 electrons to the right side of the reaction:

2 I^- --> I2 + 2e-

For the reduction reaction, a charge of +2 must exist on both sides. Add 5 electrons to the left side of the reaction to accomplish this:

5e- + 8 H+ + MnO4^- --> Mn^2+ + 4H2O

Next, both half reactions must have the same number of electrons so that they will cancel. Multiply the oxidation half by 5 and the reduction half by 2.

5(2I^- --> I2 + 2e-)
2 (5e- + 8 H+ + MnO4^- --> Mn^2+ + 4 H2O)

Step 4: Add half-reactions:

10 I^- --> 5 I2 + 10e-
16 H+ + 2 MnO4^- + 10e- --> 2 Mn^2+ + 8 H2O

The final equation is:

10 I^- + 10e- + 16 H+ + 2 MnO4^- --> 5 I2 + 2 Mn^2+ + 10 e- + 8 H2O

To get overall reaction, cancel out electrons and any H2Os, H+, and OH- that appear on both sides:

10 I- + 16 H+ + 2 MnO4^- --> 5 I2 + 2 Mn^2+ + 8 H2O

Step 5: Confirm mass and charge are balanced. There is +4 net charge on each side.
Factors affecting Reaction Rate
The rate of a reaction will increase if either of the following occurs: an increase in number of effective collisions, or a stabilization of the activated complex to the reactants.

1. Reactant concentrations
2. Temperature
3. Medium
4. Catalysts
The formula for the Gibbs Free Energy Change for a Redox reaction is....
Delta G = -nFE
How is Temperature related to volume?
Directly proportional V = T
"Charle's Law"
For a system at equilibrium, which of the following statements is false?

a. the system is at maximum entropy
b. the forward reaction will continue.
c. the reverse reaction will continue.
d. the change in entropy of the system is zero
e. none of the above
e. none of the above.
Sulfate is not soluble in water when combined with which of the following?

a. Ca
b. Ba
c. Sr
d. B and C only
e. all of the above
e. all of the above.
How is pressure related to volume?
Inversely related P = 1/V
"Boyles Law"
Which phase changes are "endothermic"?
Solid - Liquid - Gas = Fusion, Vaporization, Sublimation
Le Chatelier's Principle: Changes in Temperature
Heat can be considered as a product (exothermic rxn) or as a reactant (endothermic rxn).

Depending on reaction, if temp was increased or decreased, it would alter the equilibrium.
When a substance absorbs heat, it is always true that

a. change in entropy is negative
b. change in enthalpy is negative
c. change in enthalpy is positive
d. change in gibbs free energy is negative
e. change in gibbs free energy is positive
c. change in enthalpy is positive.
What is the closest value to Faraday's constant?

a. 9500 C
b. 96,500 C
c. 96,499 C
d. 96,501 C
e. 96,450 C
C. 96,499 C

Faraday constant = 96,485.34 C/mole
What is molecular weight of SOCL2?
To find molecular wieght of SOCl2, add together the atomic weights of each of the atoms:

1S = 1 x 32 amu = 32 amu
1O = 1 x 16 amu = 16 amu
2Cl = 2 x 35.5 amu = 71 amu

molecular weight = 119 amu
What is the standard heat of a reaction?
∆H˚rxn= (sum of ∆H˚f of products)-(sum of ∆H˚f of reactants)
If a capillary has a higher osmotic force than the interstitial fluid surrounding it, then which of the following will occur?

a. water will flow into the capillary
b . water will flow into the interstitial fluid
c. water will flow out of the capillary
a. water will flow into the capillary
What is the best explanation for why Ca2+ has a larger atomic radius than Ar?

a. the calcium cation has less electrons.
b. the calcium cation is not a noble gas.
c. the calcium cation has more electrons.
d. the calcium cation has less protons.
e. the cal
d. the calcium cation has less protons.
The Values of the Spin Quantum number are directly dependent on....

a. the principle quantum number
b. the angular momentum quantum number
c. the magnetic quantum number
d. none of the above
e. all of the above
d. none of the above

spin is always -1/2 and +1/2, opposite to each other.
117g NaCl in 500ml H2O, Kf= 1.86C/M
What's the molality of the solution?
What's the total freezing point?
2 mol NaCl/ 0.5 kg H20 = 4M (van hoff i =2)
∆Tf = -iKfm
∆Tf = -(2)(1.86)(4) = -15 degrees C
What is the Normality of a 2.0 M solution of phosphoric acid, H3PO4, for an acid-base titration?
N = 6

N = molarity x n

n = number of hydrogens exchanged.

N = (2.0moles/L) x (3 equivalents H3SO4/L) = 6 N
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