Intro to Stoichiometry & the Mole

Particles = atoms, molecules, peas or baseballs! The Mole: Substances are composed of particles. To measure specific amounts, we must count the # of particles BUT atoms, ions and molecules are soooo small, counting each one would be impossible! Therefore we use a term to represent a certain amount of particles: 1 MOLE = 6.02 x 1023 particles Particles = atoms, molecules, peas or baseballs! 6.02 x 1023 is Avogadro’s number

Ex. How many atoms are in 1 mole of Mg? 6.02 x 1023 atoms How many molecules are in 1 mole of CO2? 6.02 x 1023 molecules

MOLAR MASS: Ex. KI = (39.09 + 126.91)= 166.00 g/mol The mass of a molecule or element measured in grams/mole. Ex. KI = (39.09 + 126.91)= 166.00 g/mol Ex. O2 = (2 x 16.00) = 32.00 g/mol Ex. He = 4.00 g/mol

What is the mass of 5 moles of He atoms? What is the mass of 3 moles of NaCl? x = 20.0 g Write one example! x = 175.3 g

How many moles of silver are in 9.5 x 102g? How many moles of MnO2 are in 35.0g? x = 8.8 mol of Ag Write this! x = 0.403 mol of MnO2

Advogadro’s # tells us that: 1 mol = 6.02 x 1023 atoms/molecules Write this! Advogadro’s # tells us that: 1 mol = 6.02 x 1023 atoms/molecules How many atoms are in 3 moles of He? x = 1.81 x 1024 atoms

Write this! Stoichiometry: Is the use of proportions, from a balanced chemical equation, to determine the quantity of substances involved in a chemical reaction. Chemical equations show the proportional relationships among the products & reactants

Calculate: 25.0 moles How many moles of C are in 300g? How many moles of NaOH are in 160g? What is the mass of 6 moles of CaCl2? How many molecules are present in 1.258x10-5g of NaCl? How many molecules are present in a 0.003 g sample of H2 gas? 4.00 moles 665.88g 1.30 x 1017 molecules 9 x 1020 molecules

Ex.1 2Mg + O2 → 2MgO 2 : 1 : 2 Mole Ratio – describes the ratio in which the substances combine/form If one wishes to produce 4 moles of MgO, then 4 moles of Mg are needed, & 2 moles of O2 are needed. If 0.5 moles of O2 are available then 1 mole of Mg is needed, & 1 mole of MgO will be produced

Ex.1 How many moles of nitrogen gas & hydrogen gas are required to make 7.24 mol of ammonia? N2 (g) + 3H2(g) → 2NH3(g) 3.62 mol of N2 are needed & 10.9 mol of H2 are needed.

Ex.2a How many moles of Lithium are needed to react with fluorine gas to make 435g of lithium fluoride? 2 Li + F2 → 2 LiF x = 16.7694 moles of LiF were made 2:2 ratio, means the same # moles for Li & LiF 16.8 moles of Li are required

You can use a gram ratio to use 1 step to go from 435g LiF to 116g Li Ex.2b How many grams of Lithium are needed? You can use a gram ratio to use 1 step to go from 435g LiF to 116g Li 2 Li + F2 → 2 LiF Gram ratio (2 x 6.94) : (19.00 x 2) : (2 x 25.94) 13.88g of Li : 38.00g of F2 : 51.88g of LiF x = 116g of Li. x = 116g of Li.

Write this! Ex.3 How many grams of NaClO3 must be decomposed to produce NaCl & 52.8 g of oxygen gas? 2NaClO3 → 2NaCl + 3O2 Gram ratio (106.44 x 2) : : (32.00 x 3) 212.88g : : 96.00g 117g NaClO3

Sheet – due next class Typo!!!!!! #5b 7.75g of P4 #5d P4