Cheat Sheet Midterm Chem 205 Fall 2024 PDF

## Law vs. Theory - Law does not explain a body of facts. - Theory does explain a body of facts. ## Solid, Liquid, Gas - Solid: Hard, atoms are in a fixed shape, vibrate. - Liquid: Fluid, atoms take shape, more hitting. - Gas: Fluid, atoms all over, most space. ## Homo vs. Hetero - Homogenous = s...

## Law vs. Theory - Law does not explain a body of facts. - Theory does explain a body of facts. ## Solid, Liquid, Gas - Solid: Hard, atoms are in a fixed shape, vibrate. - Liquid: Fluid, atoms take shape, more hitting. - Gas: Fluid, atoms all over, most space. ## Homo vs. Hetero - Homogenous = solution. - Heterogenous = mixture, steel, milk & brass & blood. ## Separation Methods - Filtration = coffee filter. - Distillation: heating flask. - Chromatography = ink. - Electrolysis = compound → elements like H₂O. ## Density - D = m/V or V = m/d or M = d x V ## Extensive vs. Intensive - Ext = depend on amount, mass, volume, heat. - Int = do not depend, melting, boiling point, density. ## Physical Change - Condensation - Sublimation - Melting - Solidification - Vaporization - Liquification ## Physical vs. Chemical - Physical = gas, melts, boils, temp, seperates. - Chemical = reacts, burn. ## Kinetic vs. Potential - Kinetic = thermal, mechanical, electrical, acoustic. - Potential = gravitational, electrostatic, chemical, nuclear. ## Law of conservation of energy - Endothermic = heat absorbed. - Exothermic = heat emitted. ## Qualitative vs. Quantitative - Qualitative: physical appearance or feel. - Quantitative: #'s or units. ## Temp - C → K +273.15 - K → C -273.15 ## Precision vs. Accuracy - Precision = ↓ accuracy. - Accuracy = ↑ precision. - Should agree with one another. - Close to true =#. ## Relative Error - % relative error = (observed value - accepted value)/ accepted value × 100%. ## % yield - % yield = actual yield/theoritical yield × 100 ## Standard Deviation - S = √((∑(X_i - X)²)/(n-1)) - n = # of data points - Xi = each individual - X = sample mean ## Significant Figures - 0.0055 = 2 s.f. - 12 = infinite - 5.5 = 2 s.f. - 0.001 = 1 s.f. - 99.80 = 4 s.f. ## Addition/Subtraction - Addition/subtraction = Least s.f. after the decimal. ## Multiplication/Division - Multiply/division = Least s.f. ## Scientists - Rutherford = atomic nucleus, gold foil. - Milikan = charge of electron, spectrometer. - Thomson = charge/mass ratio of electron, cathode ray. - Dalton = atomic weight. - Becquerel/Mane Curie = radiation, radioactivity ## Atomic, Mass, Ionic - Atomic # = # of protons. - Mass # = # of protons and neutrons. - Ionic charge = ions. | | | |------|------| | 15 | protons | | P | Ionic charge | | +3 | protons and neutrons| | 30 | | ## Isotopes - Element mass = (relative abundance₁/100 × atomic mass₁)+(relative abundance₂ / 100 × atomic mass₂)+... +( (relative abundance_n/100 × atomic mass _n) ## Periodic Table - Period = row. - Groups = column I. ## Naming Compounds - Electronegativity = ↑ increases. - High electronegativity = acquire electrons. - Ionic = metal + nonmetal, roman numerals - I = 1, II = 2, III = 3, IV = 4, V = 5, VI = 6, VII = 7 - All ionic compounds that are soluble in water are electrolytes. - Covalent = nonmetal + nonmetal, prefixes. - Mono = 1, di = 2, tri = 3, tetra = 4, penta = 5, hexa = 6, hepta = 7, octa = 8, nona = 9, deca = 10 ## Oxidation States - + to zero. - CO₂: X + (-2)(2) = 0, X = +4. - CO₂^-2: X + (-2)(2) = -2, X = +2. - SO₄^-2: X + (-2)(4) = -2, X = +6. ## Oxidation and Ionic # - Ionic # is: +1, +2, +3, +4, -3, -2, -1, 0 on periodic table. ## Free Elements - Free elements have an oxidation state of zero. - P₄ = 0 - Au = 0, But Ca⁺² = +2, Same as charge but F = 0 not -1 - Fluorine = always -1. - OF₂: -1(2) = -2, so 0 = +2 - Group 1 = +1, Group 2 = +2, Group 3 = +3. - NaCl: Na = +1, Cl = -1. - H with nonmetals = +1, H with metals = -1. - 0 = -2 except with Fluorine or Peroxide (ClO₂) - Group 17 = -1, Group 16 = -2, Group 15 = -3. ## Oxidation Reduction Reaction - Fe(s) + CuSO₄ (aq) → FeSO₄ (aq) + Cu(s) - Fe(s) + Cu⁺²(aq) + SO₄^-2(aq) → Fe²⁺(aq) + SO₄^-2(aq) + Cu(s) - Fe(s) + Cu⁺²(aq) → Fe ²⁺(aq) + Cu(s) - ↓ - Reducing agent - ↓ - Oxidizing agent - ↓ - Oxidized lost electrons - ↓ - Reduced gained electrons - Oxidation = Gaining electron - Reduction = Reducing charge - Limiting reactant is the one that disappears. ## Solubility - Memorize all - Memorize all - Periodic table, first 20. ## Acid Base - H + OH = H₂O. - H₂SO₄ (aq) + NaOH (aq) → H₂O (l) + Na₂SO₄ (aq) ## Acid base - H₂SO₄ (aq) + NaOH (aq) → H₂O (l) + Na₂SO₄ (aq) - 2H⁺ + SO₄^-2 + 2Na⁺ + 2OH^- → 2H₂O + 2Na⁺ + SO₄^-2 - 2H⁺ + 2OH^-→2H₂O - H⁺(aq) + OH^-(aq) → H₂O (l) ## HC₂H₃O₂ (aq) + KOH (aq) → H₂O (l) + KC₂H₃O₂ (aq) - Acetic Acid is a weak acid. - HC₂H₃O₂ (aq) (aq) + K⁺ + OH^- →H2O (l) + K⁺(aq) + C₂H₃O₂^- (aq) - HC₂H₃O₂ (aq) + OH^- → H₂O (l) + C₂H₃O₂^- (aq) ## 2HNO₃ (aq) + Mg(OH)₂ (s) → 2H₂O (l) + Mg(NO₃)₂ (aq) - Strong acid nitrate. - 2H⁺ + 2NO₃^- + Mg(OH)₂(s) → 2H₂O + Mg⁺² + 2NO₃^- - 2H⁺ (aq) + Mg(OH)₂ (s) → 2H₂O (l) + Mg⁺² (aq) ## Mol - Molecules - mol x avogadro's # = molecules/atoms. ## Atoms - Moles - atom/avogadro's # = mol. ## g - mol - g/molar mass = mol. ## g - mol - atom - g/mol × 6.022 × 10²³ = atoms ## Molar mass - atoms-> mol - g - atom / avogadro's # × molar mass = g. ## Percent Composition - element = molar mass(periodic table)/total molar mass(compound) × 100 ## Empirical formula 1. Percent composition/molar mass 2. Then divide by smallest mol. ## Molecular formula 3. Everything above. Then, find the total molar mass of the empirical formula and divide by the given g. - given g/molar mass of empirical formula 4. Multiply # by the Emperical formula. ## Molarity - Molarity = mol/Volume - Molarity × Volume = moles. - M₁V₁ = M₂V₂ ## Chemical Change - Na₂H₄ + N₂O₄ - > Na + H₂0 - (Reactants) (Products) ## Acids and Bases |Strong Acids (Strong Electrolytes) | Strong Bases (Strong Electrolytes)| nonelectrolyte = Br₂ or gluclose | |------|------|------| | HCl <br>HBr <br>HI <br>HNO₃ <br>HClO₄ <br>H₂SO₄|LiOH<br>NaOH<br>KOH| ~ Does not produce ions| |Weak Acids (Weak Electrolytes) | Weak Base (Weak Electrolyte)| | | H₃PO₄ <br>H₂CO₃ <br>CH₃CO₂H <br>H₂C₂H₄ <br>C₄H₆O₆ <br>C₆H₈O₇ <br>C₉H₈O₄ |NH₃ | | ## % by mass -% by mass = (molar mass)/ total molar mass ## Sigma (σ) and Pi (π) bonds - 1 σ = 1 bond. - 1 π = 2 bonds. - Atomic mass unit = 1 amu = 1.66054 × 10^-27 kg. - Avagadro's number (N) = 6.022 x 10²³ mol^-1. - Definition of Joule = 1 J = 1 kg-m²-s^-2 - Definition of Pascal = 1 Pa = 1 kg-m^-1s^-2. - Gas constant = R = 0.08206 L-atm-mol-K^-1 = 8.314 J- mol-K^-1. - Planck's Constant = h = 6.626 x 10^-34 J-s. - Pressure units = 760 mm Hg = 760 torr = 1 atm = 101.325 kPa = 1.01325 bar. - Rydberg Constant = R = 1.0974 x 10⁷ m^-1. - Speed of light = c = 2.9979 × 10⁸ m-s^-1. - Temperature = 0K = 273.15 °C. - nm = x10^-9m. ## Photons = hc/λ - Usually given in nm, so change to m. - # of photons = E_total/E_photon. ## Electrons configuration/Quantum |n (energy level) | l (sublevel)| m_l (orbital)| m_s | |------|------|------|------| | 1 | s (0)| -- | ↑ +1/2 | | | | ↓ -1/2| | 2 | s (0)| -- | ↑ +1/2 | | | | ↓ -1/2| | | p (1)| --| ↑ +1/2 | | | -- | ↓ -1/2 | | | -- | ↑ +1/2 | | | -- | ↓ -1/2 | 3 | s (0)| -- | ↑ +1/2 | | | | ↓ -1/2| | | p (1)| -- | ↑ +1/2 | | | -- | ↓ -1/2 | | | -- | ↑ +1/2 | | | -- | ↓ -1/2 | | d (2)| -- | ↑ +1/2 | | | -- | ↓ -1/2 | | | -- | ↑ +1/2 | | | -- | ↓ -1/2 | | | -- | ↑ +1/2 | | | -- | ↓ -1/2 | 4 | s (0)| -- | ↑ +1/2 | | | | ↓ -1/2| | | p (1)| -- | ↑ +1/2 | | | -- | ↓ -1/2 | | | -- | ↑ +1/2 | | | -- | ↓ -1/2 | | d (2)| -- | ↑ +1/2 | | | -- | ↓ -1/2 | | | -- | ↑ +1/2 | | | -- | ↓ -1/2 | | | -- | ↑ +1/2 | | | -- | ↓ -1/2 | | f (3)| -- | ↑ +1/2 | | | -- | ↓ -1/2 | | | -- | ↑ +1/2 | | | -- | ↓ -1/2 | | | -- | ↑ +1/2 | | | -- | ↓ -1/2 | | | -- | ↑ +1/2 | | | -- | ↓ -1/2 - Plumbous (Pb⁺²) = electron configuration. - Plumbic (Pb⁺⁴) = electron configuration. ## Bohr Theory - Cannot handle systems with more than one electron. - Treats the electron as a particle. - Predicts the wavelengths of the lines in the emission spectrum of hydrogen. - Only certain orbital radii are possible. ## Periodic Table Trends - Atomic Radius - Ionization Energy - Electron Affinity - Nonmetallic character - Metallic character - Arrows are pointing towards increasing. ## Ionization energy trick - Group 16 has electron pairing which makes it slightly less ionized than group 15. ## 2 Elements - Columbic Attraction - NaF < KF < MgO - MgO < KF < NaF - KF < NaF < MgO - KF = NaF < MgO - MgO < KF = NaF - Look at the left side, even though O is further than F, Mg is closer, so it wins. ## Molarity - Molarity = 10^-pH. ## Graham's Law - Rate (A)/Rate(B) = √(M_B / M_A), M = molar mass. ## Balancing and identifying molecules - 4A₂(g) + 6B₂(g) → 4AB₂(g) + 2A₂(g) - 2A₂(g) + 6B₂(g) → 4AB₂(g) - Balanced Equation: 2A₂(g) + 3B₂(g) → 2AB₂(g) - Limiting reactant (Reagent) = B₂, because A had a leftover after the reaction. ## Orbitals Hybridization | **Total Electron-Domains ** | **Bonding Domains** | **Nonbonding Domains** | **Molecular Geometry** | **Example** | **Hybridization** | |------|------|------|------|------|------| |2 | 2 | 0| Linear| B-A-B <br> =C=O <br> F-Be-F|sp| |3 | 3 | 0| Trigonal planar| H₂C=O <br> BF₃|sp² | |3| 2 | 1| Bent | H₂O <br> SO₂|sp² | |4| 4 | 0| Tetrahedral| CH₄ <br> SiCl₄|sp³| |4| 3 | 1| Trigonal pyramidal | NH₃ <br> PCl₃|sp³| |4| 2 | 2| Bent| H₂S <br> O=C=O|sp³| |5| 5| 0| Trigonal bipyramidal| PCl₅ |sp³d| |5| 4| 1| Seesaw | SF₄|sp³d| |5| 3| 2| T-shaped| ClF₃|sp³d| |5| 2| 3| Linear| XeF₂|sp³d| |6| 6| 0| Octahedral| SF₆|sp³d²| |6| 5| 1| Square Pyramidal | BrF₅|sp³d²| |6| 4| 2| Square Planar| XeF₂|sp³d²| - **Cannot handle systems with more than one electron.** - **Treats the electron as a particle.** - **Predicts the wavelengths of the lines in the emission spectrum of hydrogen.** - **Only certain orbital radii are possible.** ## Moles - Molar mass of Br₂:(2 × 79.9 g/mol) = 159.8 g/mol - Molar mass of NH₃: (14.0 + ( 3 × 1.0)) = 17.0 g /mol - Molar mass of NH₄Br: (14.0 + (4 × 1.0) + 79.9 g/mol = 97.9 g/mol - Moles of Br₂: (5.0 g/159.9 g/mol) = 0.0313 mol - Moles of NH₃: (3.0 g/17.6 g/mol) = 0.176 mol - Limiting reactant = Br₂ - 0.0313 mol Br₂ x (8 mol NH₃)/ (3 mol Br₂) = 0.0835 mol NH₃ - Br₂ is the limiting reactant. - Moles of NH₄Br: 0.0313 mol x 6/3 = 0.0626 mol - Mass of NH₄Br: 0.0626 × 97.9 g/mol = 6.13 g - % yield = (4.71 g/6.13 g) x 100 = 76.8%. ## PV = nRT - P = Pressure - V = Volume - n = mole - R = gas constant 0.08206 L. atm. K^-1 - T = 298.15 K - n = PV/RT - n = (2.50 atm)(5.00 L)/(0.08206 L. atm. K^-1)(298.15 K) = 0.511 mol - Moles of H₂ =( 2/3) × 0.511 mol =0.3406 mol - Moles of O₂ = (1/3) x 0.511 mol = 0.1703 - Molar Mass of H₂O = 2(1.008) + 15.999 = 18.015 g/mol. - Mass = moles x molar mass = 0.3406 mol × 18.015 g/mol = 6.14 g - We use mol of H₂ because it has more moles than O₂.