Chapter 11 Notes, Part I

Chapter 11 Notes, Part I What is a mole? One Step Problems

What is a mole? A furry, burrowing woodland creature, revered by many and adored by all? Maybe! • But not really in chemistry!

A Mole... is a unit of measurement that tells how many particles of something you have!

much like a dozen (12), a gross (144) or a ream (500) is just a unit that groups smaller numbers into big ones...but its a big one; a REALLY big one!

1 mole = 6.022 × 1023 particles! 602,200,000,000,000,000,000,000 particles or flowers (that’s a lot of flowers!)

What are particles? Particles could be anything, but because of the size of the number, we usually mean Atoms, molecules, or formula units.

Avogadro’s Number The number 6.02 x 1023 is called Avogadro’s number or NA This is due to Amadeo Avagadro’s research leading to the discovery, not the discovery of the number itself.

Obj. 1…Formula vs. Molecular Mass • Formula mass = total mass of ionic compounds - starts with a metal • Molecular mass = total mass of molecular compounds - starts with a non-metal • To calculate… - find mass of each element on P.T. (whole #s) - multiply mass by subscript and/or coefficient - add all masses together for total mass

Obj. 1 cont… • Practice… Al2(SO4)3 S3F6 27 x 2 = 54 16 x 12 = 192 19 x 6 = 114 32 x 3 = 96 32 x 3 = 96 210 amu 96 + 114 = 54 + 96 + 192 = 342 amu molecular mass formula mass

Obj. 1 cont… two compounds chemically bonded together…NOT multiply!!! • more practice… CuSO4 5H2O 16x4= 64 2x1 16 3CaC2O4 64 32 64 + 32 + 64 + 5(18) = 250 amu 40 x 1 = 40 16 x 4 = 64 12 x 2 = 24 40 + 24 + 64 = 128 x 3 = 384 amu

Obj. 2 cont… • recall that one p+ or n0 = 1.67 x 10-24 grams • therefore…one mole of nucleons = 1 gram ** 1.67 E -24 grams x 6.02 E 23 particles = 1 • amu = g/mole atomic mass molar mass • one mole = ~ 6.02 x 1023 atoms, molecules or ions in a compound ~ molar mass of compound or element ~ 22.4 liters of any gas at STP (standard temp. and pressure) 760 mmHg 0°C 101.3 kPa 273K 1 atm

Obj. 3-7…Mole Conversions • use ‘mole map’ to solve mole conversions… ** going awayfrom moles = x ** going towardmoles = ÷  by molar mass x by 22.4 Liters Mole Grams  by 22.4 x by molar mass  by 6.02 x 1023 x by 6.02 x 1023 # of atoms/ molecules

Obj. 3-7 cont… • Practice, practice, practice… 2.0 moles He = ____________ atoms He 2 16 = 18 2.0 moles H2O = ____________ grams H2O 67.2 liters O2 = ____________ moles O2 2 16 = 18 27 grams H2O = ____________ moles H2O

Obj. 3-7 cont… • more practice… 3.61 x 1024 molecules NaCl = ____________ moles NaCl 5.0 moles CO2 = ____________ liters CO2

Practice Problem #1 How many moles are in 2.57 x 1025 atoms He?

Practice Problem #2 How many molecules of CO2 are in 25.3 moles?

Practice Problem #3 How many moles of O2 are in 29.3L of O2 gas?

Practice Problem #4 If you have 3.6 moles of N2O (Nitrous oxide) how many liters would you have?

Practice Problem #5 How many grams of iron are in 3.5 moles?

Practice Problem #6 How many moles of Na2O are in 355.1g?

Chapter 11 Notes, Part I

Télécharger la présentation

Plus de contenu associé