Unit 3 Quiz 2

Mole: unit of measurement in Chemistry

Liters in one mole: 22.4 liters

particles in 1 mole: 6.022(10²³)

grams in 1 mole: sum of amount of grams in each atom per compound

Go through moles, always necessary in equation

Stoichiometry

  • Moles to moles

    • start by taking the given amount of moles in the equation

    • then multiply that by the amount of moles in the original equation on the bottom to cancel out, and the number of moles corresponding with what is wanted on the top

    • Ex1: In order to produce 3 moles of oxygen gas, how much sodium chlorate is required? Given equation: 2NaClO3 —> 2NaCl+3O2

      • Equation: 3 mol O2 times x 2 NaClO3/3 mol O2. 6/3=2. 2 moles NaClO3

Molar Conversion

  • create train tracks to aid in the process, making things cancel out

  • conversion is all dependent on the problem

  • if there are grams in the problem, there will be 3 variables; otherwise, there will be 2

  • ex2: How many formula units, molecules, are in 100.0 g lead(IV) sulfate?

    • 100.0 g Pb(SO4)2/1(1 mol Pb(SO4)2/399.34 g Pb(SO4)2)(6.022(10²³)/1 mol Pb(SO4)2)

Limiting reactants

  • create 2 equations; start with grams of the equation and use the same element to determine the limiting reactant

Percent composition

  • calculate the amount of grams for each element in the compound, then divide that by the overall mass of the compound

Emperical formula

  • emirical formula for compound

  • take percent form and multiply it by mol over amoun tof grams in that element

  • divide by the smallest amount of grams

  • combine to get chemical formula

Molecular formula

  • find molecular formula by takiing percent, pultiplying it by oberall molecular formula, then dividing by the amount of grams in teh original element

  • whatever average number received is the answer