Moles

Counting Unit in Chemistry

Agenda:

Size of Atoms Moles: a counting unit in chemistry

What is a mole? Why do we use moles? Mole calculations

Factor Label Method

Atoms are very, very small particles Too small to see To small to use an optical microscope

Use a scanning tunneling microscope that is able to detect the electron clouds (due to the negative charge of the electrons)

Size of Atoms: DiameterSome estimates

Atoms including the electron cloud 1 x 10⁻¹⁰ meters

Nucleus 1 x 10⁻¹²m

Proton 1 x 10⁻¹³ m (note: mass: 1x 672 x 10⁻²⁴g)

Electron 1 x 10⁻¹⁶m

Atoms are so small: 1 x 10⁻¹⁰ metersQuarks to Quasars, Powers of Ten

Review: Scientific Notation:aka: exponents, power of ten, etc. Positive exponents:

1 x 10⁶ atoms Negative exponents:

1 x 10⁻⁶ atoms Multiplying with exponents:

(1.5 x 10³ atoms) x ( 4.2 x 10⁶ atoms) (3.4 x 10³ atoms) x (2.0 x 10⁻⁶ atoms)

Dividing with exponents: (1.5 x 10³ atoms) / ( 4.2 x 10⁶ atoms) (3.4 x 10³ atoms) / (2.0 x 10⁻⁶ atoms)

More information: Appendix near the back of the textbook

Moles

Counting Unit in Chemistry

Alternative names for numbers

Gross of pencils

Moles Video: 4+ minutes

http://ed.ted.com/lessons/daniel-dulek-how-big-is-a-mole-not-the-animal-the-other-one

Review: http://ed.ted.com/lessons/daniel-dulek-how-big-is-

a-mole-not-the-animal-the-other-one#review DigDeeper

http://ed.ted.com/lessons/daniel-dulek-how-big-is-a-mole-not-the-animal-the-other-one#digdeeper

The Mole and Avogadro’s Number What is a mole in chemistry?

How much is a mole? - - -

When are moles used?

Moles Why are moles used?

How are they measured? (Standards) The amount of substance that contains as

many particles as there are in exactly 12 grams of C-12.

The amount of substance that contains Avogadro’s number of particles.

Molar mass – using the Periodic Table

Salt particle- NaClModel of NaCl as an ionic compound Each salt particle in this photomicrograph

would require the model to be multiplied by 10⁶ or more

Formula Unit: NaClRepresents the repeating units that make up an ionic compound Such as NaCl, CaCl, Al₂O₃

New Term

Amounts: How can we determine the amount of salt particles in this picture?

Mole Conversions (Factor Label Method) Moles ↔ Grams

3.5 moles of He = ? Grams40 grams of He = ? Moles

Molar mass: 1 mole of He = ? Grams

Mole Conversions Moles ↔ Particles (atoms, molecules, compounds, etc.)

3.5 moles of He = ? Atoms12.04 x 10²³ atoms of He = ? Moles

1 mole = atoms

Review scientific notation

Mole Conversions Moles ↔ Volume of Gas (at STP)

3.5 moles of He = ? Liters 100 Liters of He = ? Moles

1 mole of a gas = Liters

Mole Flow Chart

Mole

Practice problems: Moles and Mass What is the mass of 0.5 moles of S?

How many grams is equivalent to 0.137 moles of Fe?

4.63 mol P = ? grams P

Practice problems How many moles are in 84.3 grams of Si?

50 grams of Ne = ? moles of Ne

Mole and Atom Conversions How many atoms of Al are in 2.5 moles?

How many atoms of Ag are in 0.26 moles?

How many atoms of He are in 0.0023 moles?

Mole and Atom Conversion How many moles of P contains 1.0 x 10²³

atoms?

How many moles of Au are in 2.8 x 10²º atoms?

Moles, Moles, Moles Lab

Sample in a jar

Mass Moles Atoms1 mole = ? grams 1 mole = ? atoms

Molar Mass of Compounds NaOH H₃PO₄

H₂O PCl₃

MgCl₂ H₂SO₄

Mole Conversion of Compounds How many grams are in 5 moles of CO₂?

How many atoms are in 5 moles of CO₂?

How many liters are in 5 moles of CO₂?

A Mole is a Number

Review

Carbon has 6 protons