UNIT 3 MOLE CONCEPT

UNIT 3 MOLE CONCEPTINTRODUCTIONRAMAN GILLIANCHRISTIANKANDOLA GATUSSANTOS The mole concept is a method that determines the mass or weight used when dealing with large quantities of atomsCONTENTS

Relative Mass Atomic MassThe MoleMolar Mass

2RELATIVE MASS Any objects mass that is expressed by comparing it mathematically to another objects mass

The comparison of atoms with equal numbered masses without knowing the mass of a single atom

ATOMIC MASS Mass of an atom

Atomic mass of a substance is found by comparing its mass to an atom that is taken as standard

The standard atom has changed over time. At first it was hydrogen, then oxygen and now it is carbon

The changes were made in order to make the measurements more precise

Atomic Mass Unit (u): a unit of relative measurement assigned to the masses of individual atoms

1/12 the mass of a carbon-12 atom

The atomic mass on the periodic table is based on the carbon standard

(MOL)EThe amount of a substance that contains 6.02 x 10 particles

Used to talk about a number of atoms, molecules, ions, and electrons

1 mole of a substances atom has a mass that is equal to the atomic mass of a single atom of the substance

Mole Road MapThis diagram is a creative way to describe mole relationships.

6QUANTITIES OF A MOLEIn the case of atoms, the number of grams necessary to have one mole is the same as the atomic mass of that particular atom

The mole concept is a method that determines the mass or weight used when dealing with large quantities of atomsThe number of atoms in each mole is the same, but the mass differs

Example 4-43.01 x 1023 CO2 molecules x 2 oxygen atoms x 1 mol oxygen atoms 1 CO2 molecule 6.02 x 1023 oxygen atoms

= 1.00 mol oxygen atomsIf a steel cylinder contains 3.01 x 1023 carbon dioxide molecules, how many moles of oxygen atoms are in the steel cylinder?

2 oxygen atoms in each CO2 molecule

Example 4-5.75 mol CO2 x 6.02 x 1023 CO2 molecules mol= 4.5 x 1023 CO2 moleculesHow many carbon dioxide molecules are in .75 mol of CO2 ?Unitary rate in molecules per mole of CO2 is 6.02 x 1023 moleculesmol

Example 4-726g Carbon x 1 mol Carbon 12.0g Carbon

= 2.2 mol Carbon

How many moles of carbon are in 26g of carbon?The mass of a mole of carbon atoms is the atomic mass in grams on the periodic table:1 mol of carbon corresponds to 12.0 g of carbon

Example 4-80.75 mol CO2 x 6.02 x 1023 CO2 molecules x 2 oxygen atomsmol CO2 CO2 molecule

=9.0 x 1023 oxygen atomsHow many oxygen atoms are in 0.75 mol CO2 ?1 CO2 molecule has 2 oxygen atoms1 mol oxygen atoms corresponds to 6.02 x 1023 oxygen atoms

Example 4-926.98 g6.02 x 1023 atoms

= 4.48 x 10-23 g/atomWhat is the mass of one atom of aluminum?The mass of a mole of aluminum atoms is the atomic mass listed on periodic table:26.98g corresponds to 6.02 x 1023 atoms

(MOL)AR MASS Is the mass of one mole of atoms, ions, molecules, or formula units

Formula units is the simplest formula that provides the smallest whole number ratio of ions in a compound

For a compound the mass is found by adding the atomic masses of all the elements in a compound

Example 4-10Atomic MassNumber of AtomsMass

Carbon 12.0x 12 =144

Hydrogen 1.01x 22 =22.2

Oxygen 16.0x11 =176

Add the masses

144+22.2+176=342 gWhat is the molar mass of sucrose, C12H22O11 ?

Example 4-112(27.0g) + 3(32.1g) + 12(16.0g)= 342.3 gWhat is the molar mass of aluminum sulphate, Al2(SO4)3 ?2 mol of Al atoms each with molar mass = 27.0 g3 mol of S atoms each with molar mass = 32.1 g12 mol of O atoms each with molar mass = 16.0 g

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