Drill: Calculate the % composition of each element in

MgN2O3

CHM II HW•Review PP 06•Work the problems attached to Poly’s website.

Molar Conversions

Moles•The standard unit of

measure for the amount of a

substance in numbers

Dozen= 12 of anything

Moles= the amount of a

substance that would = its mass in

g from the PT

Moles= 6.022 x 1023

of anything

Molar Conversions• Mass to moles

• Volume of a gas to moles

• Particles to moles

• Volume of a solution to moles

Moles First

Mass to Moles•Use atomic masses from the periodic table

•NaCl = 58.5 g/mole

Gas Volume to Moles•At STP: 22.4 L/mole

•Non-STP: PV = nRTPV

RTn =

Particles to Moles•Use Avogadro’s Number

•6.02 x 1023 atoms, molecules, etc/mole

Soln Volume to Moles

•Multiply molarity times volume

•n = M x V

Solution Measures•Molarity (M) = the number of moles of solute per liter of solution

•Others later

Calculate the atomic mass of the element made up of the

following isotopes:99.50 % H-10.30 % H-20.20 % H-3

Calculate the atomic mass of the element made up of the

following isotopes:5.0 % Pu-242, 5.0 % Pu-243

80.0 % Pu-244, & 10.0 % Pu-245

•Convert 7.0 g of silicon to

moles

Convert 250 g of CaCO3

to moles

Convert 3.0 moles of helium

to grams

Convert 11.2 L of oxygen gas at

STP to moles

Convert 0.20 moles of helium

to volume at STP

Convert: 2.0 x 1024 atoms

He to moles

Convert 3.0 moles of glucose

to molecules

Convert 250 mL of 0.10 M HCl

to moles

Convert 6.8 g NH3 to volume of gas at STP

Drill: Determine the volume

required to make 60.0 g NaOH into a 0.75 M solution

Convert 3.0 x 1025 molecules of CO2

to mass in kg

Drill: Calculate the number

molecules in 32 g of Fe2O3

First Test•Next Thursday on nomenclature, molar conversions, & reactions.

Calculate the number of atoms

in 16 ng of Fe2(SO4)3

EmpiricalFormula

•Lowest whole number ratio of elements in a compound

•C6H12O6: EF = CH2O

Determining Empirical

formulas from percent

composition

• Assume 100 g• Change % directly to grams• Use molar conversions to

convert grams to moles• Divide each molar amount

by the smallest molar amount

Find empirical for a compound with:

70.0 % Fe30.0 % O

Find empirical for a compound with:

40 % Ca12 % C48 % O

Find empirical for a compound with:

40.0 % C6.7 % H

53.3 % O

MolecularFormula

•The actual whole number for each element in the

compound

Molecular FormulaC6H12O6

Empirical FormulaCH2O

Solving MF from EF1) Solve empirical mass

2) Divide EM into MM

3) Multiply EF by quotient

Drill: Calculate the mass of solute

required to make 40.0 mL of

0.25 M Pb(NO3)2

Test Review on Nomenclature,

Molar conversions, & % Composition.

Calculate the % composition of each element in

Pb(NO3)2

Calculate the empirical formula of a substance containing

62.7 % Po, 28.8 % O, & 8.4 % N.

Calculate the molecular formula of a substance with an empirical formula of NH2 & a molecular mass of 32 g/mole.

Name each of the following:

•SeO MgS

•PbO2 Cl2O

•KNO3 ScCl3

Derive formulas for each:

•Cesium oxide

•Barium chloride

•Calcium phosphate

•Manganese(II) chlorate

Name each of the following:

NH4Cl BaSO4

KC2H3O2 K2HPO3

KNO3 CuBrO

Li2CO3 MgC2O4

Name each of the following:

HCl H2SO4

H2S H3PO3

HNO3 HBrO

H2CO3 HBrO4

Calculate the number of

hydrogen atoms in 1.8 kg of PH5.

Calculate the volume at STP of

6.0 ng of NO.

Calculate the mass of KBr required to make 250 mL of a 0.40 M solution.

Chapter 3 General

•Define all the Key Terms on page 74

Atomic Mass

•Work problems:

1 - 9

on page 75

Avogadro’s Num.

•Work problems:

11 - 18

on page 75

Molar Conversions

•Work problems:

18 - 26

on page 75 & 76

% Composition

•Work problems:

27 - 34

on page 76

Empirical Formula

•Work problems:

35 - 46

on page 76 & 77

Balancing Rxns

•Work problems:

49 & 54

on page 77

Stoichiometry

•Work problems:

55 & 64

on page 77 & 78

Limiting Reactant

•Work problems:

65 & 74

on page 78 & 79