S

What To Memorize: Exam 2

Chapter 4

Solute vs. Solvent vs. Solution

  • Solute: The substance (solid) that is dissolved in the solvent.

  • Solvent: The liquid that dissolves the solute, present in greatest abundance.

  • Solution: A homogeneous mixture of two ore more pure substances.

  • When water is the solvent, the solution is called an aqueous solution.

Molarity Solution (M) = (moles solute)/(L solution)

  • M=\dfrac{mol}{V}

  • Volume is in Liters

Dilution Equation: McVc=MdVd

  • Mc and Md = molarity of the concentrated solution

  • Vc and Vd = the volumes of the two solutions

  • c = concentrated

  • d = dilute

Strong Acids

  • Hydrochloric Acid (HCl)

  • Hydrobromic Acid (HBr)

  • Hydroiodic Acid (HI)

  • Chloric Acid (HClO3)

  • Perchloric Acid (HClO4)

  • Nitric Acid (HNO3)

  • Sulfuric Acid (H2SO4)

Weak Acids

  • Hydrofluoric Acid (HF)

  • Acetic Acid (CH₃COOH)

Strong Bases

  • Group 1A metal hydroxides

  • Heavy group 2A metal hydroxides (Ca(OH)2) and down

Assigning Oxidation States

  1. The oxidation state of an atom in a free, uncombined element = 0

  2. The sum of oxidation numbers of all atoms must equal the total charge (neutral = 0, ion = charge)

  3. In compounds,

    1. Group 1A = +1 (not including H)

    2. Group 2A = +2

    3. B and Al = +3

    4. F = -1

  4. In compounds, H = +1

  5. In compounds, O = -2

  6. In their binary compounds with metals

    1. Group 5A = -3

    2. Group 6A = -2

    3. Group 7A = -1

  7. Higher order rule takes precedence

Balancing Redox Reactions

  1. Divide the reaction into half reactions

  2. Balance all atoms in half reactions except “H” and “O”

  3. Balance “O” by adding H2O

  4. Balance “H” by adding H

  5. Balance each half reaction electronically by adding e-

  6. Multiply each half reaction by an integer to get electrons in each half reaction to be the same

  7. Next step depends on the type of solution:

    1. Acidic Solutions: Combine the two half reactions, canceling anything that is the same on both sides of the arrow

    2. Basic Solutions: Add OH- to both sides of the reaction to balance the H+. H+ + OH- will yield H2O, then add the two half reactions

Chapter 5

Formulas

Change in internal enthalpy: \Delta E=E_{f}-E_{0}

Exchange of energy between system and surroundings: \Delta E=q+\omega

  • q = heat

  • w = work

If \Delta E >0 = Endothermic (the system absorbs energy from its surrounding in the form of heat)

If \Delta E <0 = Exothermic (the system releases energy in the form of heat)

Work: PV or -PV

  • P = pressure

  • V = volume

Enthalpy: H=E+PV

Change in Enthalpy: \Delta H=\Delta E+P\Delta V

Enthalpy of Reaction: \Delta H_{rxn}=H_{products}+H_{reactants}

Chapter 6

Formulas

Specific of light: c=\lambda v

  • \lambda = wavelength

  • v = frequency

Constant for speed of light: c=3.00\times 10^{8}m/s

Energy is proportional to frequency: E=hv

  • h = plank’s constant

  • v = frequency

Plank’s constant: h: 6.626\times 10^{-34}J\cdot s

Reminders

Fahrenheit: F = \dfrac{9}{5}\left( °C+32\right)

Celsius: C = \dfrac{5}{9}\left( °F-32\right)

Kelvin: K = °C+273