Stoichiometry

The Mole What is a mole?

No not this type of mole either

The Mole Chemists use a measurement called ‘the mole’ A mole is like a dozen eggs= 12 eggs or a pair of shoes= 2 shoes However, the mole is a very large number  This is because atoms are so small that chemists need a lot to be able to find their mass

How big is the mole?? A mole contains x of anything  x is a.k.a AVOGADRO’S NUMBER How big is a mole exactly?  If you could count 10 million numbers every second, it would take you 2 billion years to count an avogadro’s number out  If you had a mole of unpopped popcorn kernals it would cover the entire planet to a depth of 9 miles  If you poured out a mole number of cans of pop out you would cover the entire earth with an ocean of pop 200 miles deep

Therefore, 1 mole= x particles or x particles/mol 1 mole Cl= x particles 1 mole of H= x particles 2 moles=

Atomic Molar Mass The mass (in grams) of 1 mole of a given element To find this for each element you must look at the periodic table:  1 mole of C= 12 g (or 12g/mol)  What is the mass of 1 mole of oxygen?  What about 2 moles of oxygen?  3 moles?

Molecular Molar Mass Is the mass (in grams) of all the elements in the molecule To find the mass: 1. find each element’s atomic mass and 2. add all of the atomic masses together Ex NaOH:  Na= 1 x 23 g/mol  O= 1x 16 g/mol  H= 1 x 1g/mol 40 g/mol of NaOH

Ex H2O Ex. H2SO4

Find the following masses MgBr2, Ga(NO2)3, CrI2, BeSO4 Assignment: molar mass worksheet

Stoichiometery Given two out of these three values for mass, moles and/or molar mass, you can figure out the value of the missing value Mass= moles x molar mass Moles= mass/molar mass Molar mass- find using periodic table Particles= moles x x 10 23

Examples Moles to mass mol of CaO mol of BeSe mol of Li3P mol of Be2SO4

examples Find moles given mass g of H2O g of HBr g of CaCl g of Ca3(PO4) g of MgCl g of H3PO4 1 mol, 1mol, mol, mol,0.16 mol, mol

Assignments Assignment: molar mass/ moles/mass assignment

examples Moles to particles: 1. 1 mol of Fe 2. 3 mols CO mols H2O HBr x 10 23, x1024, 4.04x 1023, 6.023x 1022

Examples Particles to moles x atoms of Fe x atoms of O x atoms of H x atoms of K 1.0 mol, mol, mol, 2.99 mol

Examples Mass from particles 1. mass of 1.20 x molecules of water? 2. mass of 2.41 x atoms of barium hydroxide? 3. mass of 1.51 x atoms of neon? 4. mass of 7.53 x molecules of CH 4 ?

Particles from mass 1. How many molecules does 36.0 grams of water represent? 2. How many molecules does 11.0 grams of CO 2 represent? 3. How many atoms does 3.0 grams of carbon represent? 4. How many formula units does grams of calcium carbonate represent?

assignment Stoichiometery problems with # of molecules Stoichiometery assignment with all the examples