Is the SI base unit use to measure the amount of a substance. THE MOLE: Is the SI base unit use to measure the amount of a substance. Ex: 1 mol H2(g) or H2(g) or 5 H2O (l) 5 mol H2O(l) 3 mol NaCl(s) or 3 NaCl(s)

2 mol of H (atoms) 1 mol H2O(l) 1 mol of O (atoms) 6 mol of H (atoms) 3 mol H2O(l) 3 mol of O (atoms)

4 mol Al3+ (ions) 2 mol Al2O3 6 mol O2- (ions)

Calculating the number of mole of particles in a compound

Ex. How many moles of oxide ions are in 1.5 mol Al2O3. 1st 1 mol Al2O3 ---- 3 mol O2- ions. 2nd 1.5 mol Al2O3 × 3 mol O2- ions/mol = 4.5 mol O2- ions. (Answer) (Make sense?)

THE MOLE ? (1 mol) 1 mol (atoms) = (# of “particles”) A ream of paper = 500 sheets A box of pencils = 12 pencils A pack of candies = 50 candies A bottle of aspirins = 100 tablets (1 mol) (# of “particles”) 1 mol (atoms) = 6.02 × 1023 atoms

1 mol = 6.02 × 1023 particles (Avogadro’s Number)

1 mol = 6.02 × 1023 particles (Avogadro’s Number) atoms (Cu) particles

1 mol = 6.02 × 1023 particles (Avogadro’s Number) atoms (Cu) molecules (CO2) particles

1 mol = 6.02 × 1023 particles (Avogadro’s Number) atoms (Cu) molecules (CO2) particles formula units (NaCl)

1 mol = 6.02 × 1023 particles (Avogadro’s Number) atoms (Cu) molecules (CO2) particles formula units (NaCl) ions (Fe2+)

1 mol = 6.02 × 1023 particles (Avogadro’s Number) atoms (Cu) molecules (CO2) particles formula units (NaCl) ions (Fe2+) electrons (e-)

How large the Avogadro’s Number is ? 1 mol of atoms = 6.02 × 1023 atoms Could you count the number of atoms in 1 mol? If you are able to count one atom per second, 6.02 × 1023 ÷ 3600 sec = 1.67 × 1020 hours 1.67 × 1020 hours ÷ 24 days = 6.96 × 1018 days 6.96 × 1018 days ÷ 365 years = 1.91 × 1016 years 19, 100, 000, 000, 000, 000 years !!! (19 pentillion one hundred quadrillions of years !!!)

Mole –to– Number of Particles Conversions:

Calculate the number of molecules in 1.5 mol of H2O. 1.5 mol of H2O x Factor   1.5 mol of H2O x = 9.0 x 1023 molecules of H2O

You can use proportions: Or just multiply the number of particles given by the Avogadro’s Number: 1.5 mol x 6.02 × 1023 molec./mol = 9.0 × 1023 molecules You can use proportions: 1 mol --- 6.02 x 1023 molec. X = 1.5 mol x 6.02 x 1023 molec. 1 mol 1.5 mol --- X Or you can use the equation: n(x) =

You can use proportions:   You can use proportions: 1 mol --- 6.02 x 1023 molec. X = 1.5 mol x 6.02 x 1023 molec. 1 mol 1.5 mol --- X Or using equation: n(x) =

Number of Particles –to– Mole Conversions:

Calculate the number of moles in 1.806 x 1024 atoms of copper. 1.806 x 1024 atoms of Cu x Factor   1.806 x 1024 atoms of Cu x = 0.3 x 101 mol = 3.00 mol of Cu

Or just divide the number of particles given by the Avogadro’s Number: x = = 0.3 × 101 mol Cu = 3.00 mol Cu

Calculating the number of particles in a compound

Ex. How many atoms of each element there are in 2.5 mol of N2O4? 1st Calculate the # of mol of each element: Nitrogen (N): 2.5 mol (N2O4) × 2 mol (N)/mol N2O4 = 2nd Calculate the # atoms present: x 6.02×1023 atoms (N)/mol = = = 5 mol (N) 5 mol (N) 30.1 × 1023 = 3.01 × 1024 atoms (N)

Oxygen (O): 2.5 mol (N2O4) × 4 mol (O)/mol (N2O4) x 6.02 ×1023 atoms (O)/mol = 10 mol (O) 10 mol (O) = = 60.2 × 1023 = 6.02 × 1024 atoms (O)

Mass and Mole.

Molar Mass: Is the mass in grams of one mole of any pure substance. Atomic masses --- P. Table)

Atomic mass (Na) = 22.99 a.m.u.(atomic mass units) Molar mass (Na) = 22.99 g/mol 1 mol (Na) = 22.99 g 1 mol (Na) = 22.99 g = 6.02 × 10 23 atoms.

Mole – to - Mass conversions.

Determine the number of moles in 60.75 g of magnesium. 60.75 g (Mg) x factor   60.75 g (Mg) x = 2.499 mol (Mg) Answer Make sense?

Or divide the mass given by the molar mass:   = 2.499 mol (Mg) Answer

The molar mass of a compound: M(x)

The molar mass of a compound Is the mass (in grams) of one mole of a compound It represents the sum of the masses of every particle that makes up the compound.

Example: Calculate the molar mass of Na2SO4. M(Na2SO4) = m (Na) + m (S) + m (O) = 2(22.99 g) + 1(32.06 g) + 4(16.00 g) = 45.98 g + 32.06 g + 64.00 g M(Na2SO4) = 142.04 g/mol.

Mole – to - Mass conversions in a compound:

Calculate the mass of 3.25 mol of H2SO4. 1st – Calculate its molar mass: M(H2SO4) = m (H) + m (S) + m (O) = 2(1.01 g) + 1(32.06 g) + 4(16.00 g) = 2.02 g + 32.06 g + 64.00 g = 98.08 g/mol. (Molar Mass) 2nd – Convert the 3.25 mol to g: 3.25 mol (H2SO4) × 98.08 g (H2SO4)/mol = 319 g (H2SO4) -- Answer

Volume and Mole.

Molar Volume: 1 mol = 22.4 dm3 (L) (For any gas at STP) STP – Standard temperature & pressure (0oC & 1 atm) zzxxSXZX

Mole –to– Volume Conversion:

Calculate the volume of 0.881 mol of a gas at STP. V = 0.881 mol x factor   V = 19.7 L Answer

Or multiply the number of mole given by the Molar Volume: 0.881 mol × 22.4 L/mol V = 19.7 L

Volume –to–Mole Conversion:

How many moles of nitrogen gas will be contained in a 2 How many moles of nitrogen gas will be contained in a 2.00-L flask at STP? # mol = 2.00 L x factor   V = 0.089 mol Answer

Or divide the volume given by the Molar Volume: 22.4 L/mol = 0.089 mol

Mole Conversions Summary

6.02 x 1023 particles The molar mass 1 mol = 22.4 L at STP (gases)

Mass (g) Mol # of Particles Volume (L) (STP) Molar Mass 1 mol 1 mol Molar Mass 6.02 x 1023 1 mol 22.4 L 1 mol 1 mol 6.02 x 1023 1 mol 22.4 L