Chemistry Final Flashcards
Dilution
Dilution Equation
(Mi)(Vi)=(Mf)(Vf) Mi= Initial molarity Mf= Final Molarity Vi= Initial Volume Vf= Final volume
Molarity
Moles of solute per liter of solution
Concentration = amount of stuff per unit of area or volume
Molarity = moles of solute / liters of solution = M notation
The “mole”, grams->mole conversions, etc…
Use the molecular weight to determine the Moles of a compound, add each mass of each element, pay attention to subscripts.
Avogadro’s Number
6.022x10^23
number of units in one mole of any substance (defined as its molecular weight in grams),
Percent Compostion
(Mass of X/ Mass of Whole) * 100
Molecular weight
Empirical Formula
Tells us:
- what elements are present in the compound
- the ratio of the elements in the compound (but not the exact number)
Steps to Calculate Empirical Formula
p159-163
0) Assume 100g
1) Calculate the Moles
2) Calculate the Ratio
3) Scale the Ratio (if needed)
Molarity
Brackets indicate molarity of a substance [CaSO4] = 1.00 M
Dilution: MiVi = MfVf ,
where i is the initial amount and f is the final amount
Steps to solving molarity problems:
- Find the givens in the problem, and what we need to find
- Take what is given and put it over one
- Use stoichiometry to put all numbers with correct units: ex. Ml / 1000 = L
- Solve for the unknown using the molarity formula M = moles / liters
- Convert the answer into a different form if the problem calls for grams instead of moles or for milliliters instead of liters using stoichiometry
- May need to multiply by the number of moles of an ion in the formula to get an answer respective to the number of units for that ion in the formula
Use mole: mole ratio, ex. If need Fe ions in Fe2O3 and given the mass of Fe2O3, use the ratio 2 mol Fe: 1 mol Fe2O3
Steps to writing Dilution Problems
- Write the known values and what you need to find according to the problem
- Plug the values into the equation and calculate the final answer
- May need to multiply by the number of moles of an ion in the formula to get an answer respective to the number of units for that ion in the formula
Concentration and Molarity:
Concentration is how much stuff per unit area or volume, while molarity is how many moles per liter of solution.
Dissociation
the process when an ionic compound dissolves in water, its ions separate and become surrounded by water molecules.
Electrolytes
Free Ions in solution, conduct electricity
Solute
The substance being dissolved
Solvent
The substance doing the dissolving
Strong electrolyte
completely converted to ions when it forms an aqueous solution
Stoichiometry Train
On our Stoichiometry train we now have to places in which we can get on. We can now either start at the grams station or the volume station.
If we get on at the grams station and are trying to get to the moles station we have to use the molar mass ticket. You determine molar mass by the periodic table.
Stoichiometry Train
If we started at the volume station instead of the grams station then we get to the moles station by molarity. We figured out how to find molarity above.
Now we are at the moles station. To get to the mole:mole station we look at the balanced equation.
Stoichiometry Train
We have now arrived at the mole:mole station and are on our way to the moles station. To get to the moles station we once again use the balanced equation ticket.
Now that we are at the moles station we have to look at the original problem and determine if we need to go to the grams station or the volume station to get off.
Stoichiometry Train
If you need to get off at the grams station you need to use the molar mass ticket. Once again, you get the molar mass from the periodic table.
If you need to get off at the volume station instead then you need the molarity ticket which was previously discussed.
Limiting Reagent
1) Ride the train for each reagent
2) Compare the theoretical/max yield determined for each reagent
3) Identify the limiting reagent and correesponding max/theoretical yield
Scientific Notation
Left (+) #
Right (-) # to the power
T= Tera G= Giga M=Mega K= Kilo D=Deca
12 9 6 3 1
d=deci c=centi m= milli Micro n=nano p= pico
- 1
- 2
- 3
- 6
- 9
- 12
Density = mass/volume
the amount of matter present in a given volume of a substance
K = C + 273.15
F = C × 1.8 + 32
C = ( F - 32) / 1.8
F= C*1.8+32
Writing Equivalence Statements
1) Always start with the unit with the prefix
2) Always relate it back to the base unit
3) The number “1” always goes with the unit with the prefix
4) The scientific notation always goes with the base unit.
Unit Conversion Calculations
1) Take what they give you and put it over one
2) Write the necessary equivalence statements
3) Track your units
Sig Fig (Multiplication/Division)
The answer of the calculation can only have as many sign digits as the number int he calculation with the least # of sign. digits
Sig Fig (Addition/ Subtraction)
The answer to the calculation can only have a many decimal locations as the number in the calculation with the least number of decimal places
Sig Fig Rules
1) All non-zero digits are significant
2) Any zero that falls between two significant digits is also significant (captive zeros)
3) Zeros’s to the right of the decimal and to the right of a sign. digit are also significant
4) Zeros to the left of the decimal place are not significant unless the decimal point is explicitly written.
States of Matter
Solid- rigid; has a fixed shape and volume
Liquid- take shape to its container and has a definite volume
Gas- no fixed volume or shape, takes shape and volume of its container
Chemical Property
ability to change into a diff substance
Physical Property
-substance can change with out becoming a new substance
Physical Change
involves a change in one or more physical properties, but no change in fundamental components that make up the substance. The most common physical changes are changes of state: solidliquidgas
Chemical change
involves a change in fundamental components of the substance; a given substance changes into different substance or substances. Also called reactions.
ex. plants growing, wood burning, silver tarnishing
Atomic Structure
Electron
Rel. Mass: 1
Rel. Charge 1-
Atomic Structure
Proton
Rel Mass 1836
Rel Charge 1+
Atomic Structure
Nuetron
Rel Mass 1839
Rel Charge none
Atomic Structure
Nucleus
Small dense center of positive charge in an atom.
Contains Protons and Neutrons
Nucleus is then surrounded by electrons
Atomic Number (top of Sym)
Identifies the number of protons in a nucleus
Atomic Mass (bottom)
sum of the # of nuetrons and the # of protons in a given nucleus.
Isotopes
atoms with the same number of protons but different number of neutrons. A/Z X A-atomic mass Z- # of protons, atomic # X-Elemental symbol i.e. 23/11 Na versus 24/11 Na
Diatomic
Have No Fear Of Ice Cold Beer
molecules made up of two atoms
Hydrogen, Nitrogen, Flourine, Oxygen, Iodine, Chlorine, Bromine
Ionic Compounds
-pairing of Ions, one cation and at least one anion; two or more ions combine to form a neutral compound
-free ions in solution -electrolytes
Cations- metals
Anions- non-metal
Molecular Compounds
- Molecule stays in tact in solution, separated but not broken
- no free ions -no charge, no electricity is conducted
- share electrons via covalent bonds
Ideal Gas Law
1 atm = 760 Torr = 760 mm Hg
PV=nRT
R = 0.08206 atm*L/mol *K
Avogadro’s Principle
Equal volumes of gases, under the same temperature and pressure, contain equal numbers of molecules.
0.08206 atmL/molK
Combined Gas Law
P1V1/T1= P2P2/T2
Charles Law
P1/T1= P2/T2 & V1/T1=V2/T2
Boyle’s Law
P1V1= P2V2
Coulomb’s law
The magnitude of the electrostatic force of interaction between two point charges is directly proportional to the scalar multiplication of the magnitudes of charges and inversely proportional to the square of the distance between them
Acids
is any species that increases the H+ concentration in solution
strong-fully ionizes in solution- strong electrolyte
Most organic acids are weak acids (carbon-based), CH3CHOOH acetic acid, H3PO4, HCN
Most inorganic (mineral) acids are strong acids ie. HCI, HBR, HI HNO3, H2SO4
Base
any species that increases the hydroxide ion (OH-) concentration in solution
Bases that partially ionize in solution are called weak bases
Amimes most common class of weak bases, Amines increase the hydroxide concentration by reacting with water.
If an acid ad a base combine in equal amounts then they neutralize eachother
Whenever they combine the products are water and a salt (metal cation + anion)
Strong Acids
HCl- Hydrochloric acid HBr- hydrobromic acid HI- Hydroiodic acid HNO3- Nitric acid H2SO4- sulfuric acid HCIO4- Perchloric acid
Strong Bases
LiOH- Lithium hydroxide NaOH- Sodium hydroxide Mg(OH)2- Magnesium hydroxide Ca(OH)2- Calcium hydroxide Ba(OH)2- Barium hydroxide Sr(OH)2- Strontium hydroxide
Weak Acids
CH3COOH- acetic acid(HC2H3O2) HCOOH (or HCO2H)- formic acid C6H5COOH (or C6H5CO2H) -benzoic acid H3PO4- Phosphoric acid HCN- Hydrocyanic acid H2CO3- carbonic acid
Weak Bases
NaHCO3- sodium hydrogen carbonate Na2CO3- sodium carbonate NH3- Ammonia CH3NH2- Methylamine C3H7NH2- Propylamine C6H5NH2- aniline
Oxidation-Reduction (Redox) Reactions
Ions are formed when an atom gains or loses electrons
Oxidation- LEO- loss of electrons
Reduction- GER- Gain of electrons
Oxidizing agents are reduced so they gain elections
Reducing agents are oxidized so they have lose of electrons.
Determining Oxidation Numbers
1) The oxidation number of a pure element is alway zero. (ie. Fe= Fe^0 & H2 = H^0)
2) The oxidaiton number of an element can often be predicted from its position on the periodic table. (ie. Grp 1, Grp2, Grp 16, Grp 17)
- except when bonded to themselves
- halids are normally 1-….except when bonded to oxgen(2-) and flourine(-)
Full Ionic Equation
Every combound, element, that participated in the reaction.
Net Ionic Equation
The parts of the equation which react. (think of a net, what gets caught)
Spectator Ions
The ions that do not react. (think of the people watching a game, after the game they are unchanged.)
Ratios of molecules in reactions based on balanced equations
Use the coefficients of the balanced equation
Law of Conservation of Mass
states that matter can be changed from one form into another, mixtures can be separated or made, and pure substances can be decomposed, but the total amount of mass remains constant
