Chemistry Notes Chapter 3 Stoichiometry One mole 6 022x10 23 entities Ionic compound forms between Ca and I How many iodide ions does it contain Remember to do the formula Ca charge of 2 I 1 Formula CaI2 Mass Percent Empirical Formula Find moles of each element in formula mass to mole conversion Convert divide each by smallest subscript one element will become 1 then multiply by x to make all numbers whole numbers Empirical Formula Mass Spectrum theeeen Molecular Mass formula Molecular Formula to Empirical If X 1 2 3 Multiply by 1 2 3 X Ratio between molar mass and empirical formula mass Combustion Analysis Different chambers each one tells how much of each chamber is produced Then determine mass fraction of each element convert mass to moles and then determine empirical formula then molecular formula Writing and Balancing Chemical Equations know 7 diatomic molecules Pick most complicated one and work from there All other elements and molecules make fraction relative to most complicated one Then multiply by smallest whole number coefficient to avoid any remaining fractions Last molecule left put how many are needed on opposite side over the subscript number Ex 1 C8H18 25 2 O2 8 CO2 9H2O 16 9 25 on right requires 25 2 O2 on left Then adjust by multiplying all by 2 Quantitative relationships in balanced equations used in stoichiometrically equivalent molar ratios from balancing coefficients 1 Use molar ratios to determine how much of one substance forms from or reacts with another Balanced equations reveal how many moles of what forms how many moles of something else mole to mole conversions mole ratios Solution Concentration Calculation of Molarity Need relation between the moles of the dissolved substances in the solution and the volume of the solution Solutions consist of a lesser amount of the solute dissolved in a greater amount of the solvent Moles Liter is concentration Molarity is moles of solute per liter of solution Always in LITERS Molarity is a conversion factor used to convert btwn volume of solution and moles of solute Dilution Only solvent changes Limiting reactant problems Determine limiting reactant by assuming each reactant is the limiting one work out each problem as though each is whichever yields the least product is the limiting reactant