The Mole

Mole = unit amount (ex. dozen, couple…)

Avogadro’s Number

  • molecules/atoms per mole

Molar Mass: mass in grams of 1 mole of __ substance (compound or element)

  • 1 moles of any elements contain the same number of atoms; the masses of 1 mole of different elements are different

  • Molar Mass = Atomic/Formula mass in amu

Mass —> Moles and vice versa

  • same with compounds, divide by total molar mass

Number of Atoms

  • multiply mole number by avogadro’s number

  • same with compounds

  • for number of Carbon atoms in this comopund

Standard Temperature and Pressure

  • 273 Kelvins (standard Temp)

  • 1 atm, 101.325 kPa (standard Pressure)

  • 1 mole = 22.4 L (standard Molar Volume)

Ideal Gas Law

  • Gases described by this law exhibit ideal behavior; when given any 4 of the terms below the 5th will be able to be found

    • P = gas pressure

    • V = gas volume

    • T = temperature in Kelvins

    • R = ideal/universal gas constant

    • n = number of moles of gas

Empirical Formulas

  • molar amounts used to compute whole-number ratios to derive empirical formulas of substances

  1. convert from grams to number of moles

  2. Divide each subscript by the smaller subscript

  3. Empirical formula (should end with whole number subscript, if not close multiple to get whole number)

Percent Compositions with Empirical Formulas

  • Convert percentages to out of 100 g

  • Convert to Moles, then find ratio

    • The result her eis: CO2

Derivation of Molecular Formulas

  • comparing molecular/molar mass to empirical formula mass for the number of formula units per molecule

  • then applied to each subscript, determine molecular formula

Solutions

  • Concentration: relative amount of a given solution component

    • Solvent: the medium the other component(s) are dissolved in

      • Aqueous Solution: solution where water is the solvent

    • Solute: the component being dissolved (described with dilute and concentrated)

  • Molarity: number of moles of solute per liter of solution

    • In a solute, calculate the number of moles (conversion) over number of Liters

    • Mass of NaCl given molarity and volume

  • Molality: ratio of number of moles of solute to the mass of solvent in kg