Unit 2: Chemical QuantitiesUnit 2: Chemical QuantitiesSCH 4CSCH 4C

The Chemist’s DozenThe Chemist’s Dozen

How many in a couple?How many in a couple? How many in a few?How many in a few? How many in a dozen?How many in a dozen? How many in a ream?How many in a ream?

2

3

12

500

Just like you associate these terms with a number, the mole is too!

The Chemist’s DozenThe Chemist’s Dozen

The mole is the chemist’s dozenThe mole is the chemist’s dozen 1 mole = 6.02 x 101 mole = 6.02 x 1023 23 particlesparticles That is 602 sextillionThat is 602 sextillion Or Or 602 000 000 000 000 000 000 000602 000 000 000 000 000 000 000 This is called Avogadro’s numberThis is called Avogadro’s number

Avogadro’s NumberAvogadro’s Number

Like a dozen, a mole is used to measure the Like a dozen, a mole is used to measure the amount of a substance. amount of a substance.

If you have 1 dozen donuts, you have 12 If you have 1 dozen donuts, you have 12 donuts.donuts.

If you have 1 mole of donuts, you have If you have 1 mole of donuts, you have 6.02 x 106.02 x 102323 donuts. donuts. In chemistry, the mole is commonly used to In chemistry, the mole is commonly used to

count atoms, formula units and molecules.count atoms, formula units and molecules.

The Mole and MassThe Mole and Mass

The The molar mass molar mass of a substance is the of a substance is the mass of 6.02 x 10mass of 6.02 x 102323 particles of that particles of that substance.substance.

The molar mass of an The molar mass of an elementelement is equal to is equal to the atomic mass in the atomic mass in g/mol.g/mol.

The molar mass of a The molar mass of a compoundcompound is equal to is equal to the sum of the atomic mass of all the the sum of the atomic mass of all the elements present in elements present in g/molg/mol..

Molar MassMolar Mass

Find the molar mass of:Find the molar mass of:

FeFe Pt Pt

CC1212HH2222OO1111 Ca(NOCa(NO33))33

55.8 g/mol 195.1 g/mol

12C + 22H + 11O12(12.01) + 22(1.01) + 11(16.0)342.30 g/mol

Ca + 3N + 9O40.1 + 3(14.01) +9(16.0)164.09 g/mol

Relating Moles to MassRelating Moles to Mass

To calculate the mass represented by a To calculate the mass represented by a certain number of moles of a substance, certain number of moles of a substance, we use the relationship:we use the relationship:

Where Where nn= moles (mol)= moles (mol)mm = mass (g) = mass (g)

M = molar mass (g/mol)M = molar mass (g/mol)

m = n M

Finding moles…Finding moles…

How many moles are represented by How many moles are represented by 56.2g of Cu?56.2g of Cu?

n = m = 56.2gM 63.5 g/mol

= 0.885 mol

Finding Mass…Finding Mass…

Calculate the mass of 6.72 mol of Calculate the mass of 6.72 mol of NaNa22COCO33..

M = 105.97 g/mol

m = n x M = (6.72 mol)(105.97 g/mol) = 712.12 g

Time to WorkTime to Work

Pg 85 #4 and pg 99 # 9-11Pg 85 #4 and pg 99 # 9-11 Pg 94-95 #1-5Pg 94-95 #1-5 Pg 100 #12, 13Pg 100 #12, 13 Pg 102-103 #14-17Pg 102-103 #14-17

The Mole and the Number The Mole and the Number of Particlesof Particles

One mole of a substance is the amount One mole of a substance is the amount of a substance containing 6.02 x 10of a substance containing 6.02 x 102323 particles of that substance.particles of that substance. 1 mole of Na is 6.02 x 101 mole of Na is 6.02 x 102323 atoms atoms 1 mole of Cl1 mole of Cl22 is 6.02 x 10 is 6.02 x 102323 molecules molecules 1 mole of NaCl is 6.02 x 101 mole of NaCl is 6.02 x 102323 formula units formula units 1 mole of H1 mole of H22O is 6.02 x 10O is 6.02 x 102323 molecules molecules

6.02 x 106.02 x 1023 23 is is Avogadro’s Number Avogadro’s Number and is given and is given the symbol the symbol NNAA..

To calculate the number of particles in a To calculate the number of particles in a sample of a substance we use the sample of a substance we use the relationship:relationship:

The Mole and the Number The Mole and the Number of Particlesof Particles

N = n NA

Where N is the number of particles (atoms, molecules, formula units)Where N is the number of particles (atoms, molecules, formula units) n is the number of moles (mol)n is the number of moles (mol) NNAA is Avogadro’s number (atoms/mol, molecules/mol, formula units/mol) is Avogadro’s number (atoms/mol, molecules/mol, formula units/mol)

Finding the Number of Finding the Number of ParticlesParticles

How many atoms are represented by 2.6 How many atoms are represented by 2.6 mol of Fe?mol of Fe?

Finding the Number of Finding the Number of MolesMoles

How many moles are present in a sample How many moles are present in a sample containing 5.63 x 10containing 5.63 x 102424 molecules of H molecules of H22O?O?

Finding the Number of Finding the Number of Atoms in a SampleAtoms in a Sample

How many atoms of hydrogen are How many atoms of hydrogen are present in a sample containing 8.63 mol present in a sample containing 8.63 mol of methane, CHof methane, CH44??

Time to WorkTime to Work

Pg 98 #6-8Pg 98 #6-8 Pg 105 #18-21Pg 105 #18-21