THE MOLE: Is the SI base unit use to measure the amount of a substance. Ex: 1 mol H 2 (g) or H 2 (g) 5 mol H 2 O(l) or 5 H 2 O (l) 3 mol NaCl(s) or 3 NaCl(s)

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

2 mol Al 3+ (ions) 1 mol Al 2 O 3 3 mol O 2- (ions)

Calculating the number of mole of particles in a compound

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

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

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

atoms (Cu) particles

1 mol = 6.02 × particles ( Avogadro’s Number) atoms (Cu) molecules (CO 2 ) particles

1 mol = 6.02 × particles ( Avogadro’s Number) atoms (Cu) molecules (CO 2 ) particles formula units (NaCl)

1 mol = 6.02 × particles ( Avogadro’s Number) atoms (Cu) molecules (CO 2 ) particles formula units (NaCl) ions (Fe 2+ )

1 mol = 6.02 × particles ( Avogadro’s Number) atoms (Cu) molecules (CO 2 ) particles formula units (NaCl) ions (Fe 2+ ) electrons (e - )

How large the Avogadro’s Number is ? 1 mol of atoms = 6.02 × atoms Could you count the number of atoms in 1 mol? If you are able to count one atom per second, 6.02 × ÷ 3600 sec = 1.67 × hours 1.67 × hours ÷ 24 = 6.96 × days 6.96 × days ÷ 365 = 1.91 × 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 H 2 O. 1.5 mol of H 2 O x Factor molecules H2OH2O = 9.0 x molecules of H 2 O

Or just multiply the number of moles given by the Avogadro’s Number: 1.5 mol × 6.02 × molec.H 2 O/mol = 9.0 × molecules H 2 O.

Number of Particles –to– Mole Conversions:

Calculate the number of moles in x atoms of copper x atoms of Cu x Factor atoms = 0.3 x 10 1 mol = 3.00 mol of Cu

Or just divide the number of particles given by the Avogadro’s Number: x = = 0.3 × 10 1 mol Cu = 3.00 mol Cu

Calculating the number of particles in a compound

Ex. How many atoms of each element are in 2.5 mol of N 2 O 4 ? Find the # of mol of each element & then the # of atoms present: Nitrogen (N): 2.5 mol (N 2 O 4 ) × 2 mol (N)/mol N 2 O 4 = x 6.02×10 23 atoms (N)/mol = = = 5 mol (N) 5 mol (N) 3.01 × atoms (N) 30.1 × =

Oxygen (O): 2.5 mol (N 2 O 4 ) × 4 mol (O)/mol (N 2 O 4 ) x 6.02 ×10 23 atoms (O)/mol = 10 mol (O) = = 60.2 × = 6.02 × atoms (O)

Mass and Mole.

Molar Mass: Is the mass in grams of one mole of any pure substance.

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

Mole – to - Mass conversions.

Determine the number of moles in g of magnesium g (Mg) x factor = 2.5 mol (Mg) Answer Make sense?

You can divide the mass given by the molar mass: = 2.5 mol (Mg) Answer

The molar mass of a compound: M(x) M(x)

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

Example: Calculate the molar mass of Na 2 SO 4. M(Na 2 SO 4 ) = m (Na) + m (S) + m (O) = 2(23 g) + 1(32 g) + 4(16 g) = 46 g + 32 g + 64 g M(Na 2 SO 4 ) = 142 g/mol.

Mole – to - Mass conversions in a compound:

Calculate the mass of 3.25 mol of H 2 SO 4. 1 st – Calculate its molar mass: M(H 2 SO 4 ) = m (H) + m (S) + m (O) = 2(1 g) + 1(32 g) + 4(16 g) = 98 g/mol. (Molar Mass) 2 nd – Convert the 3.25 mol to g: 3.25 mol (H 2 SO 4 ) × 98 g (H 2 SO 4 )/mol = g (H 2 SO 4 ) -- Answer

Volume and Mole.

Molar Volume: 1 mol = 22.4 dm 3 (L) any gas (For any gas at STP) STP – Standard temperature & pressure (0 o C & 1 atm)

Mole –to– Volume Conversion:

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

Volume –to–Mole Conversion:

Or simple, divide the volume given by the Molar Volume: 2.00 L 22.4 L/mol = mol

Mole Conversions Summary

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

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