Conversions
Given a sample of 12.0 L of H2O (g). Calculate the amount of hydrogen atoms in this sample. (Assume STP conditions). (Molar mass of H2O = 18.015)
6.45 * 1023
How to calculate formal charge?
# valence electrons - (number of nonbonded electrons + (1/2 * number of shared electrons)
Name the (3) Van der-Waal forces
LDF (london dispersion forces)
H-Bonding
Dipole-Dipole
What 2 compounds are always formed during a combustion reaction?
Water (H2O) and carbon dioxide (CO2)
What is ZEFF? (How do you calculate it.)
Does each period have the same ZEFF or each group?
Z = Atomic Number / # protons
S = # of Shielding electrons
Zeff = Z - S
Each group will have the same calculated ZEFF.
A 0.355L soft drink contains 45.5g of sucrose (molecular weight of 342.3 g/mol).
Solve for the molar concentration (M)
0.374 M
Resonance in simple terms?
When more than one accurate lewis structure can be drawn for a compound.
PV = nRT
Describe what each letter signifies.
P = Pressure
V = Volume
n = moles
R = A constant (the value depends on the units)
T = temperature
Brønsted–Lowry definition of acid & base.
An acid is a Hydrogen ion donator (should have less after the reaction), and the base is a hydrogen ion acceptor.
Most electronegative element?
Explain using trends.
Electronegativity increase to the right, and decreases down a group. This is because more protons and less shielding electrons means the ability to attract bonded/shared electrons better.
How many milliliters of 5.0 M copper(II) sulfate solution must be added to 160 mL of water to achieve a 0.30 M copper(II) sulfate solution?
M1V1 = M2V2
(5.00 mol/L) (x) = (0.3 mol/L) (160 + x)
5x = 48 + 0.3x
4.7x = 48
x = 10 mL
What is the VSEPR shape of ammonia (NH3) explain using amount of bond/lone pairs.
trigonal pyramidal (3 bonded pairs, 1 lone pair)
Will H2O form __________ (complete with the right IMF) with NaCl because...
Which particles will be interacting in this scenario (will the O be interacting with the Na/Cl, will H be interaction with Na/Cl)
There will be ion-dipole interactions due to the fact that H2O is a polar molecule, and NaCl is composed of a cation and anion (2 charged particles/ions).
Since Na+ is a cation (postive charge) it will be attracted to the negative portion of the H2O molecule which is the O side.
Since Cl is an anion (negative charge) it will be attracted to the positive portion of the H2O molecule which are the H sides.
What is the goal of a titration?
Determine the concentration of a substance by reacting that substance with another substance of known concentration in a reaction. (mv = mv)
Explain the trends for atomic size.
Increases going across the period due to increasing Zeff; more protons for the same amount of electron shells/shielding electrons.
Decreases going down a group due to increasing shells/shielding electrons.
If a solution of MgCl2 is 1/8 M, what will its concentration be if it is diluted by 27%?
M1V1 = M2V2
(0.125) (100 mL) = (x) (127 mL)
x = 0.098 M
Two types of alloys and their differences?
Interstitial: These alloys are formed with smaller radii metals filling the gaps created by formations of a bigger radii metal.
Substitional: The alloy is created with some metal particles being replaced by other metal particles of a similar radii.
What are the two types of solids and an example of each.
Crystalline (Salts) - Specific Structure
Amorphous (Glass) - No specific structure
What does it mean if an atom has been reduced during a reaction. What does it mean if it's been oxidized.
OIL - Oxidation is lose
RIG - Reduction is gain
If it's been oxidized it lost electrons (more positive)
If it's been reduced it gained electrons (more negative)
_Al + _O2 -> _Al2O3
4Al + 3O2 -> 2Al2O3
3NaOH(aq) + H3PO4 (aq) --> Na3PO4 (aq) + 3H2O(l)
If 35.60 g NaOH reacts with 30.80 g H3PO4.
What is the limiting reactant and how much excess will there be.
Molar Mass of
NaOH = 40.00g, H3PO4 = 98.00g
Convert given NaOH to grams H3PO4 to find out how much NaOH could be used and vice versa. Determine limiting reactant (NaOH), and then subtract the used H3PO4 from total to find leftover (1.72 g).
Lattice energy increasese/decreases when the ion radii decrease.
Brief Explanation
increase
When the radii decrease this indicates that the there is a higher attractive pull on the electrons. Thus small radii indicate greater charged particles, and higher the chargers the more attractive pull they have on eachother. (For ex, lattice energy of MgO is higher than NaCl, because Mg and O are charge negative/postive 2 in stead of 1).
Calculate the frequency of radiation with a wavelength of 442 nm.
c = 3.00 x 108 m/s
1) Convert nm to m:
442 nm x (1 m / 109 nm) = 4.42 x 10¯7 m
2) Substitute into λν = c:
(4.42 x 10¯7 m) (x) = 3.00 x 108 m s¯1
x = 6.79 x 1014 s¯1
Balance the redox equation:
Fe2O3 + CO -> Fe + CO2
Show:
2Fe2O3 + 3CO -> 2Fe + 3CO2
Oxidation Half-Reaction: 3CO -> 3CO2 + 6e-
Reduction Half-Reaction: 2Fe2O3 + 6e- -> 2Fe
Oxidized = C (loses 2 e-)
Reduced = Fe (gains 3 e-)
As you move from the left to the right of the periodic table, what happens to ionic radii.
To get the points explain why
As you move across horizontally the ionic radii decreases, go up, and then continue to decrease.
This is because while the elements are still metals, they will become cations. These cations lose electrons and thus reduce one shell size to reach an octet. Thus the size decreases as across the period there are increasing amounts protons. (Short answer: ZEFF increases)
Then when the elements are no longer metals, then these elements will tend to become anions. These elements will thus gain electrons to reach an octet. However, this means they will not change in shell size. Thus, again across the period there will be a decrease. (Short answer: ZEFF stays the same).