Final Exam Flashcards
How do we determine if substance is a pure substance?
When we talk about a pure substances we refer to the submicroscopic level
How do we determine if a substance is a mixture?
Mixtures are visible to us (macroscopic level)
Within pure substances we have…
elements and compounds
Withing mixtures, we have…
homogenous mixtures and heterogeneous mixtures
What are the 2 types of properties?
Physical and chemical
What is the difference between physical and chemical?
physical properties include: density,mass appearance, color, freezing/boiling point.
Chemical properties include: flammability, reactivity (chemical changes convert one substance into another, physical does not)
What are the rules for sig figs in addition and subtraction?
Our answer has as many decimal places as the least exact measurement
What are the rules for sig figs in multiplication and division?
Your answer has as many sig figs as the least exact measurement
What are the rules for sig figs in logs?
The number of sig figs in the parenthesis (starting value) equals the number of decimal places
ex: log(4.1 * 10^-3) = 2.39
What are the rules for sig figs in antilogs?
The number of decimal places in the antilog equals the number of sig figs in the result
ex: antilog (1.325)= 10^1.325= 21.1
How do we find celsius given Fahrenheit
C = (F-32) * 5/9
How do we find Fahrenheit given celsius?
F = C * 9/5 + 32
How do we find Kelvin?
If we are given Celsius just add 273. If we are given Fahrenheit simply convert to celsius first and then add 273
What is specific heat?
It measures the ability of a substance to absorb heat
What is the formula of specific heat?
(Heat) / mass * change in temp.
What happens if we change the number of protons?
We change the element
What happens if we change the number of neutrons? What does it form?
We change the mass forming an isotope
What happens if we change the number of electrons? What does it form?
We change the charge of an element forming an ion
Elements are identified by their _____ which is equal to the number of protons
Atomic number
How do we write the notation for an element?
(Mass on top) (atomic number on bottom) and element symbol on the right
What are the two types of ions?
Cations and Anions
What is a cation?
It has a positive charge and it is formed by losing electrons
Which group of elements are most likely to be cations?
metals
What is an anion?
A negatively charge element formed by gaining electrons.
Which group of elements are most likely to be anions?
non-metals
How do we calculate average atomic mass?
Since we are given two isotopes and their percent of abundance, take the corresponding percentage of their atomic mass and add.
What is the law of constant composition?
Elements always combine in the same proportion and formula.
How do we find mass percent?
(part/whole) * 100
How is Daltons Atomic Theory outdated?
It stated that atoms of the same element were the same mass and atoms of different elements had different mass.
All matter is made of indivisible particles called atoms
Atomic Spectra helps us understand that electron energy is…
quantizied
The areas where an electron will most likely be is called a
orbital
Orbitals have a __ % probability
90%
What are the 3 types of subshells and how many orbitals do each have?
S subshells have 1 orbital
p subshells have 3 orbitals
d subshells have 5 orbitals
Each orbital can hold how many electrons?
2
What is the ground state electron configuration?
1s,2s,2p,3s,3p,4s,3d,,,
Alkali metals are in group _
Alkaline metals are in group _
Halogens are in group _
Noble gases are in group _
Alkali metals are in group 1
Alkaline metals are in group 2
Halogens are in group 7
Noble gases are in group 8
What is electronegativity?
It is a value that describes the extent to which atoms pull electrons.
Which element has the highest electronegativity value?
Fluorine
Which group has overall higher electronegativity values?
Nonmetals, they are more likely to pull electrons toward themselves
What is a non-polar covalent bond?
When we have 2 atoms that have a similar or identical electronegativity value, electrons are shared equally
What is a polar covalent bond?
When we have 2 different electronegativity values between atoms, sharing is unequal
The sharing of electrons is what type of bond?
Covalent
What is an ionic bond?
When electrons are completely transferred due to the difference in electronegativity values
What are the rules for naming ionic bonds?
The cation (metal) retains its name and the nonmetal's ending changes to -ide The only exception is polyatomic ions (retain their name)
What are the rules for naming covalent bonds?
The ending of the second element will change to-ide.
Covalent compounds always use prefixes (except for mono on first)
The only exception to this is diatomic molecules (they retain their name)
What are the 7 diatomic elements?
Hydrogen, Oxygen, Fluorine, Chlorine, Nitrogen, Iodine, Bromine
Why do we have to memorize transition metal charges?
Because they arent predictable
What are the charges for Chromium? (Cr)
2+ and 3+
What are the charges for Iron? (Fe)
2+ and 3+
What are the charges for copper? (Cu)
1+ and 2+
What are the charges for mercury? (Hg)
Hg(2) 2+ and 2+
What are the charges for tin? (Sn)
2+ and 4+
What are the charges for lead? (Pb)
2+ and 4+
How do we name binary compounds with transition metals?
No prefixes
Metals retain name, nonmetal changes to ide
Roman numerals are needed for the charge
How do we name covalent molecules?
Add prefixes (except for mono on first element) 2nd element ending changes to ide Diatomic molecules retain their name
What are the first 10 prefixes?
1: mono
2: di
3: tri
4: tetra
5: penta
6: hexa
7: hepta
8: octa
9: nona
10: deca
How do we know if a substance is an acid?
It will have an H in the beginning of the formula
What are the rules for binary acids?
Prefix will be hydro
Second element becomes ic
Add acid at end
EX: hydrochloric acid = HCl
What are the rules for polyatomic acids?
No Hydro prefix If ending was ate it turns to ic If ending was ite it turns to ous Add acid EX: H2SO4= sulfuric acid
If there are 2 bonds around the central atom the electron geometry is _______, the molecular geometry is _______. The bond angle is _______
Linear, Linear, 180
If there are 3 things around the central atom but only 2 bonds, the electron geometry is ______, the molecular geometry is _______. The bond angle is ______
trigonal planar, bent, <120
If there are 3 things around the central atom and 3 bonds, the electron geometry is ______, the molecular geometry is _______. The bond angle is _______
trigonal planar, trigonal planar, 120
If there are 4 things around the central atom but only 3 bonds, the electron geometry is ______, the molecular geometry is _______. The bond angle is _____
tetrahedral, trigonal pyramidal, <109.5
If there are 4 things around the central atom but only 2 bonds, the electron geometry is ______, the molecular geometry is _______. The bond angle is _______
tetrahedral, bent, <109.5
If there are 4 things around the central atom and 4bonds, the electron geometry is ______, the molecular geometry is _______. The bond angle is _______
tetrahedral, tetrahedral, 109.5
How do we know if a compound is polar?
We compare their electronegativity values, draw a lewis structure and make sure the molecule’s polarity isn’t canceled by symmetry.
How is symmetry unbalanced in a bond?
When we have lone pairs around central atom or when there are no identical groups around it.
What is the law of conservation of mass?
Even though reactions convert reactants to products, there still is the same number and type of product
One mole = ?
6.022 *10 ^-23 atoms/particles
What is molar mass?
The sum of all elements in a compound
We go from moles to atoms using
Avogadros Number
We go from moles to grams by
using molar mass
We go from moles to moles by
using coefficients from balanced equation
What is the difference of empirical formula and molecular formula?
An empirical formula represents the formula of a compound in the simplest way.
A molecular formula represents the formula of a compound as it exists. (can be reduced by a common factor)
Empirical : CH, Molecular: C6H6
How do we find the empirical formula?
Since we will be given 2 percent compositions for different elements,we will be doing the steps for each element.
- turn percent composition into grams (no conversion)
- Convert grams into moles
- Once you have moles for both elements, divide each calculation by the smallest mole value in order to get a ratio.
- If your ratio is not a whole number, multiply by either 2,3,4 depending on the decimal. Once you have a whole number, go back to the elements and add their ratios as subscripts.
How do we find molecular formula?
Since we will be given a Molar mass, we have to see if it will be true.
- Find empirical formula
- If values do not match, we can assume the formula was simplified and NOT the true molecular formula.
- We will then divide (molar mass molecular aka given)/ (molar mass calculated from empirical)
- once you get that value, it will let us know our empirical formula is off by a factor of it.
What is the oxidation number of free elements?
0
What is the oxidation of group 1 metals
+1
What is the oxidation of fluorine in compounds?
-1
What is the oxidation of group 2 metals?
+2
What is the oxidation of group 3 ions?
+3
What is the oxidation of hydrogen in compounds?
+1
What is the oxidation of oxygen in compounds?
-2
Oxidation is the ____ of electrons while Reduction is the _____ of electrons
Oxidation is the loss of electrons while Reduction is the gain of electrons (OILRIG)
What is a reducing and oxidizing agent?
If we have an element that is oxidized, we have a reducing agent. If we have an element reduced, we have an oxidizing agent
What are the four variables used to describe gas behavior?
P: pressure in atm or torr (760 torr = 1 atm) T: temperature in Kelvin V: volume in liters n: number of moles R: constant (0.0821)
What is the ideal gas law?
PV = nRT
What is STP (standard temp and pressure)
T: 273 K
P: 1 atm
Why is 22.4 L an important value?
Because since all gases occupy the same volume at the same temperature and pressure, we can assume that one mole of any gas at STP has a volume of 22.4 L
What is Boyles Law?
It tells us the relationship between volume and pressure (moles and temperature are constant)
As Volume increases, pressure decreases
P1V1= P2V2
What is Charles law?
It is the relationship between Temperature and volume
As volume decreases, temperature decreases
V1/T1 = V2/T2
What is Gay Lussac’s Law?
It is the relationship between pressure and temperature
As pressure increases, temperature increases
P1/T1 = P2/T2
What is Avogadros law?
It is the relationship between moles and volume
As volume increases, moles increases
V1/n1 = V2/n2
What is partial pressure?
Since gases exist in mixtures, we can identify the gas amounts for each individual element. According to Daltons Law of Partial Pressure, the total pressure is equal to the sum of all of the individual pressures
What is henrys law?
(volume dissolved/volume of solvent) / gas pressure = (ml of gas/solvent) / atm
As temperature decreases, solubility of gas
decreases
As pressure increases, solubility of gas
increases
Going from gas to solid is _______.Solid to Gas is
Sublimation, Deposition
Changes of state are what type of reaction?
Physical
Which is weaker IMF or chemical bonds?
Intermolecular forces
What are the 3 types of IMF?
London Dispersion, Dipole Dipole, Hydrogen Bonds
What is London Dispersion?
An attraction that is temporary and present in all molecules
What is Dipole-Dipole?
A permanent attraction in polar molecules
What is Hydrogen Bonding?
A Strong force that occurs when H bonds to either F,O or N
How does IMF relate to energy needed for phase changes?
Strong IMF increase energy needed for phase change
How does IMF relate to surface tension?
Strong IMF increases the surface tension
How does IMF relate to vapor pressure?
Strong IMF decreases the vapor pressure. A liquid with stronger intermolecular forces does not evaporate easily and thus has a lower vapor pressure
What is a vapor?
When a substance is present as both a gas and a liquid, the gas is a vapor. There is equilibrium between gas and liquid since it is in a closed space
What is evaporation?
It is the same as vapor but it occurs in an open system and there is no equilibrium since particle are completely escaping
When does boiling occur? evaporation?
When vapor pressure equal atmospheric pressure.When vapor pressure is less than atmospheric pressure, evaporation occurs
In lower pressure, boiling points are
lower
In higher pressure, boiling points are
higher
What is the relationship between solids and melting points
The stronger the force, the higher the melting point. Covalent crystals have the highest, Ionic have an intermediate melting point and Molecular crystals (such as Ice) have a very low melting point
When are solutions likely to form?
When 2 substances have similar IMF (except for substances that are only LDF)
What is the difference between a solute and solvent?
A solute is the thing that gets dissolved, a solvent is the thing that solute dissolves in.
A true solution is a _________ mixture
homogeneous
What happens if a solution is saturated?
No more can dissolve
What is the relationship between temperature and solubility?
As T increases, S increases
Which solutions are generally soluble?
Group 1 metals, NH4 + salts, Nitrates, acetates, Sulfates are soluble except when combined with Ca, Sr or Ba
Which solutions are generally insoluble?
Hydroxides except when combined with g1 metals or Sr, Ba
Phosphates and carbonates are insoluble except when combined with g1 metals
If we have a displacement reaction, how do we find out the products of an equation?
They simply switch partners (metal first, nonmetal second). Make sure they are still balanced
What is a complete ionic formula?
In this type of formula, anything that is aqueous, is written as individual ions. If it is a solid or liquid, they are written as wholes
What is a Net ionic formula?
To generate a net ionic formula, we need to look at the complete ionic and make only write the things that changed.
How do we solve for solution concentration?
concentration = amount of solute/ amount of solvent
How do we calculate osmotic pressure?
i (n/v)
When we have 2 substances with different concentrations and a semipermeable membrane, where will the solvent go towards?
The solution with the highest concentration
What is a hypotonic cell?
When there is a low concentraion outside the cell so water moves in (blows up)
What is a hypertonic cell?
When there is a high concentration outside the cell so water moves out (shrinks)
When looking at an activation energy diagram, what comes first?
Reactants
The Activation Energy (Ea) reaches which line?
Up to the reactants
How do we calculate reaction rates?
(appearance of product) / time
OR
(disappearance of reactant) / time
How does a catalyst affect the diagram?
It only changes the shape of the activation energy diagram since Ea is lowered
How are catalysts identified given 2 reactions?
If an element is first a reactant and then a product, it will be a catalyst
How are intermediates identified?
It is first a product, then a reactant
What should we not include in the overall reaction?
catalysts or intermediates
How do we calculate Keq? What are the units?
Keq = products/reactants In units of molarity
Are all substances listed in Keq?
NO, only gases and aqueous solutions
How do we find Keq between 2 sequences?
Mutliply them together
What does LeChatliers principle tell us?
Our reaction shifts to the side that has less
Does a catalyst increase or decrease the energy of an intermediate?
decrease
Given H+, how do we solve for pH?
take the - log
Given pH, how do we solve for pOH?
If we are given pH, simply use 14=pH + pOH and solve for pOH
How do we solve for OH- concentration given H+?
Use the Kw formula Kw = H+ * OH-
When asked to write a titration formula, what do we do?
You will be given an acid and base which will have to form a salt and water.
How do we solve for titrations?
We will have to set up our conversions. Since we will be given volume of acid, make sure it is in liters and start off with that. Once you do, convert the liters into moles using molarity. After you have moles, convert into the bases moles using coefficients from the balanced equation. After you get moles of your base, divide by the volume given in the problem.
In a dilution, what is constant? what changes?
In a dilution, concentration is reduced and amount of solute is constant
What does a large Keq tell us about the reaction?
In a large Keq (greater than one), we can assume that products are favored, it is a favorable reaction
What does a small Keq tell us about the reaction?
In a small Keq (less than one), we can assume that reactants are favored and it is an unfavorable reaction.
How does heat relate to LeChatlier’s Principle?
If we have an endothermic reaction, heat is a reactant and it will shift right. If we have an exothermic reaction, heat is a product and it will shift left
What are the 6 strong acids?
HCl, H2SO4, HI, HNO3, HBr, HClO4
What makes an acid strong? weak?
Complete dissociation in solution means an acid is strong. A weak acid has a partial dissociation in solution.
What is generally a weak acid?
Carboxyllic Acids
What bases are strong?
Generally strong bases are metal hydroxides
LiOH, NaOH, KOH, RbOH, CsOH, Ca(OH)2, Sr(OH)2
How do we tell the difference between Ka and Kb?
Ka= acid + water ⇌ H3O + conjugate base Kb= base+ water ⇌ OH- + conjugate acid
How does the K value relate to favoritism?
If we have two values with a small Ka Value, the one that is the biggest (even though they both favor reactants) is the stronger weak (acid/base).
How does the K value relate to an inverse relationship in strength of weak acids/bases?
If we determine we have a weak acid, we know the conjugate base will be strong. If we have a weak base, the conjugate acid will be strong.
When calculating concentration of H3O+ or OH-, what will determine acidic or basic?
If we have a higher H3O + concentration, it is acidic. If OH- is higher, it is basic
When does a buffer work at its best?
When ph = pKa
To find concentration of H3O+, given pH what do we do?
10 ^-pH (antilog of pH)
To find concentration of OH-, given pOHwhat do we do?
10 ^-pOH (antilog of pOH)
How do we find the sequences of polyprotic acids?
In the 1st step, we will have an acid + water = Hydronium and base (H+ when to water and created H3O+)
In the second step, our base will be our acid and we will have acid + water = Hydronium + base ( one less H+)
How do we calculate pH given molarity for acid base and Ka?
Use the pKa + log (base/acid) formula
What happens in alpha decay?
Atomic # decreases by 2
Mass # decreases by 4
What happens in Beta Decay?
Atomic # increases by 1
Mass # stays the same
What happens in positron decay?
Atomic # decreases by 1
Mass # stays the same
In a pH scale, what values indicate an acidic solution? basic?
In a pH scale, acidic is anything less than 7 and basic is anything greater than 7
In a pOH scale, what values indicate an acidic solution?
In a pOH scale, acidic is anything greater than 7, basic is anything less than 7
If we are given Ka, how do we solve for pKa?
-log
If we are given pKa, how do we solve for Ka?
10^-pKa
