09_CH3_Moles_Student

# 09_CH3_Moles_Student - Chapter 3 The Mole Click to edit...

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Click to edit Master subtitle style Chapter 3: The Mole Brady & Senese, 5th Ed

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Particles Have Characteristics Masses § Rabbit & candy cane do not have same mass § Further, same mass may not represent same number of molecules § Suppose one rabbit has a mass of 250 g. What mass in kg would a case of 24 rabbits have?
Counting Atoms By Their Mass § Atomic Mass § The mass of an atom § Provides a means to count atoms by measuring the mass of a sample § Periodic table gives atomic masses of the elements in u per atom § u = atomic mass unit § To reduce rounding errors, use most precise values possible

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Relationships § Atomic Mass u = 1 particle or amu = 1 particle § We can use this as a conversion factor to convert between these quantities. mass (u) particles u particle   1 particle u   1
Learning Check § How many atoms of C are there in 3.5 × 108 u? § What is the mass (in u) of 2.33 × 1016 atoms of H? atomic masses: C=12.0107 u; H=1.00794 u

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Relationships § 1.66×10-27 kg = 1 u § from inside back cover of book) may also be written as: § 6.0223×1023 u = 1 g § a form you will often use § Use this as a conversion factor to convert between mass quantities in u, and those in g grams (g) atomic mass units (u) × u 10     6.0223 g     23 1 × g   u 10     6.0223   23 1
Learning Check § How many u of Na are there in 55.2 kg Na? § How many g Na are there in 3.2 x 1015 u of Na?

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Counting Molecules By Their Masses § Molecular mass § Allows counting of molecules by mass § Is the sum of atomic masses of all the atoms in the compound’s formula § Ionic compounds § Do not have a molecular mass § Have analogous quantity § Formula Mass § Sum of atomic masses of all the atoms in the ionic compounds formula http://web.visionlearning.com/MW_calculator.shtml
Masses of Substances Atoms Molecules Ionic compounds Atomic Mass Molecular Mass Formula Mass # below element =– all At. Masses =– all At. Masses Zn CO(NH2)2 MgCl2 65.409 u 1C 12.011 u 1O 15.9994 u 2N 2(14.0067) u 4H 4(1.00794) u 60.05556 u Or 60.056u 1Mg 24.3050 u 2Cl 2(35.453) u 95.211 u u kg atoms u kg molecules u kg formula units

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Relationships § MM g = 1 mole § Use this as a conversion factor to convert between these quantities mole Mass (g) g   MM mole   1 mole   g   MM 1
Given that the molar mass of CO2 is 44.0098 g/mol § What mass of CO2 is found in 1.55 moles? § How many moles of CO2 are there in 10 g?

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Using Avogadro’s Number, Na § Counting formula units by moles is no different than counting eggs by the dozen (12 eggs) or pens by the gross (144 pens) § Since the individual particle is very small, the mole is a more practical quantity § It is a group, in which 6.0223×1023 individuals comprise 1 mole § The quantity, Na, is Avogadro's number and is measured as 6.0223×1023
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09_CH3_Moles_Student - Chapter 3 The Mole Click to edit...

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