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# February 24, 2014 - PowerPoint PPT Presentation

February 24, 2014. Chemical Formulas The Mole One-Step Molar Conversions. Materials. Calculator Periodic Table A good attitude about math. Chemical Formulas. Covalent: C 8 H 18 Octane # Carbon: 8 # Hydrogen: 18 Ionic: Al 2 (SO 4 ) 3 Aluminum Sulfate # Aluminum: 2 # Sulfur: 3

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## PowerPoint Slideshow about ' February 24, 2014' - osanna

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Presentation Transcript

• Chemical Formulas

• The Mole

• One-Step Molar Conversions

• Calculator

• Periodic Table

• A good attitude about math

• Covalent: C8H18

• Octane

• # Carbon: 8

• # Hydrogen: 18

• Ionic: Al2(SO4)3

• Aluminum Sulfate

• # Aluminum: 2

• # Sulfur: 3

• # Oxygen: 12

• (4 O’s in each sulfate, 3 sulfates in the compound, 3 x 4 = 12)

• The mass of one molecule, formula unit, or ion.

• Calculate by adding atomic masses together from the periodic table.

• Units: amu (atomic mass unit)

Example: HCl

• Mass H + Mass Cl

• 1.0079 + 35.453 = 36.4069 amu

Example: NH4NO3

• Mass N + 4(Mass H) + Mass N + 3(Mass O)

• 14.007 + 4(1.0079) + 14.007 + 3(15.999) =

• 80.0426 amu

• OR

• 2(Mass N) + 4(Mass H) + 3(Mass O)

• 2(14.007) + 4(1.0079) + 3(15.999) =

• 80.0426 amu

Example: PO43-

• Mass P + 4(Mass O)

• 30.974 + 4(15.999) = 94.97 amu

• The charge does not affect the mass because the mass of an electron is so very small that it is negligible (able to be ignored).

• 1 mole = 6.02 × 1023 particles

• It is the number of atoms in exactly 12.0 g of carbon-12

• It is used the same way as:

• A dozen (12)

• A pair (2)

• A score (20)

How did they come up with 6.02 x 1023anyway?

• If you divide the charge on a mole of electrons by the charge on a single electron you obtain a value of Avogadro’s number of 6.02214154 x 1023 particles per mole.

• Covalent: C8H18

• Octane

• Moles Octane: 1

• Moles Carbon: 8

• Moles Hydrogen: 18

• Ionic: Al2(SO4)3

• Aluminum Sulfate

• Moles aluminum sulfate: 1

• Moles Aluminum: 2

• Moles Sulfur: 3

• Moles Oxygen: 12

• Mass of one mole(6.022 × 1023) of any molecule, formula unit, or ion.

• Calculate by adding atomic masses together from the periodic table.

• Units: g/mol

Example: H2SO4

• 2(Mass H) + Mass S + 4(Mass O)

• 2(1.0079) + 32.066 + 4(15.999)

• 98.0178 g/mol

Example: Ca(NO3)2

• Mass Ca + 2(Mass N) + 6(Mass O)

• 40.078 + 2(14.007) + 6(15.999) =

• 164.086 g/mol

• OR

• Mass Ca + 2((Mass N) + 3(Mass O))

• 40.078 + 2((14.007) + 3(15.999)) =

• 164.086 g/mol

Amount in

moles

Mass in

grams

• Divide by the molar mass

• Multiply by the molar mass

Example: How many moles are in 2.0 g calcium chloride?

• End with: moles

• Math: divide by molar mass

• Molar mass of calcium chloride, CaCl2

• 40.078 + 2(35.453) = 110.984 g/mol

• 2.0 g CaCl2= 0.018 mol

110.984 g/mol

Example: How many grams are in 1.5 molpotassium iodide?

• End with: g

• Math: multiply by molar mass

• Molar mass of potassium iodide, KI

• 39.098 + 126.90 = 165.998 g/mol

• 1.5 mol x 165.998 g/mol = 248.997 g

• Number of particles

• Formula unit

• Molecule

• Ion

• Atom

Amount in

moles

Multiply by

Divide by

Example: How many formula units are in 6.0 molcalcium bromide?

• End with: formula units (particles)

• Math: multiply by Avogadro’s number

• 6.0 mol x 6.02 x 1023 =3.612 x 1024 f. units

• Calculator Help: Use the EE button

• EE = x 10

• 6.02 x 1023 = 6.02EE23

Example: How many moles are in 5.0 × 1022 molecules H2?