Topic 1: Stoichiometric Relationships

IB SL Chemistry

Mrs. Page

2015-2016

1.1 Introduction to the particulate nature of matter and chemical change

Understandings:• Atoms of different elements combine in fixed ratios to form

compounds, which have different properties from their component elements.

• Mixtures contain more than one element and/or compound that are not chemically bonded together and so retain their individual properties.

• Mixtures are either homogeneous or heterogeneous.• Names of the changes of state—melting, freezing,

vaporization (evaporation and boiling), condensation, sublimation and deposition—should be covered.

Applications and skills:• Deduction of chemical equations when reactants and

products are specified.• Application of the state symbols (s), (l), (g) and (aq) in

equations.• Explanation of observable changes in physical properties and

temperature during changes of state.

Theory of Knowledge:• Chemical equations are the “language” of chemistry. How

does the use of universal languages help and hinder the pursuit of knowledge?

States of MatterSOLIDS• Definite shape• Definite volume• Cannot be compressed• Particles closely packed – attractive force btwn particles• Particles vibrate

• NOTE: Absolute zero (0°K, -273°C) is that temperature at which there is no movement of particles.

• Temp. K = Temp °C + 273.15

States of MatterLIQUIDS• Take shape of container• Definite volume• Cannot be compressed• Particles more loosely packed– attractive force btwn

particles is weaker• Particles vibrate, slide past each other and rotate

States of MatterGASES• Take as much space as given• No fixed volume• Can be compressed• Particles very loosely packed– no attraction btwn

particles• Particles vibrate, slide past each other and rotate quickly

with high energy

State Changes• Endothermic:

• heat energy is taken in from surroundings (to the substance)• Melting• Boiling

• Exothermic: • heat is given off to

surroundings (from substance)• Condensation• Freezing

HEATING & COOLING CURVES

http://lessons.chemistnate.com/heating-curves.html

HEATING & COOLING CURVES

http://www.chemistrylecturenotes.com/html/heating_curves.html

HEATING & COOLING CURVES

Classifying Matter• Pure Substance: made of one type of particle. Has

distinct physical & chemical properties• Elements: atoms of the same atomic number• Compounds: fixed ratio, properties not same

• Mixtures: made of combinations of substances. Can be separated by physical means (filtering, magnets, chromatography, distillation)• Homogeneous: uniform throughout

• Ex: salt water, milk, metal alloys (brass, steel)• Heterogeneous: not uniform so properties vary

throughout mixture• Ex: raisin bran, trail mix, vegetable soup

IUPAC Naming• International Union of Pure and Applied Chemistry• Agreed naming systems for all chemical compounds• Applied worldwide• http://goldbook.iupac.org/index.html

TOK• Language is a crucial component of

communication of knowledge and meaning. Does the language of chemistry with its equations, symbols, and units promote or restrict universal understanding?

Types of ReactionsCombination/Synthesis

• Two or more reactants combine to form a single product• A + B AB

Decomposition• One reactant breaks down into two or more products• XY X + Y

Single Replacement• One element replaces another in a compound• AB + C BC + A

Double Replacement/Metathesis• Two ions in a solution switch places to form insoluble

substances and weak or non-electrolytes• AB + CD AD + CB• HCl(aq) + NaOH(aq) NaCl(aq) + H2O(l)

Classify the following Reactions1. SiO2 + Mg Si + MgO

2. SO2 + O2 SO3

3. CaCl2 + K3PO4 Ca3(PO4)2 + KCl

4. CO + O2 CO2

5. H2CO3 CO2 + H2O

6. CaCO3 + HCl H2CO3 + CaCl2

7. C4H10 + O2 H20+ CO2

8. P4O10 + H2O H3PO4

9. Cu + HgNO3 Cu(NO3)2 + Hg

10. NCl3 N2 + Cl2

11. Ag2SO4 + NH4I (NH4)2SO4 + AgI

Common Polyatomic Ions & Acids You MUST KnowName of Polyatomic Ion Formula Name of Polyatomic Ion Formula

Ammonium NH4+ Phophate (V) PO4

3-

Carbonate CO32- Phosphonate PO3

3-

Hydrogencarbonate HCO3- Sulfate (VI) SO4

2-

Hydroxide OH- Sulfate (IV) SO32-

Nitrate (V) NO3- Ethanedioate C2O4

2-

Nitrate (III) NO2- Peroxide O2

2-

Name of Acid Formula

Hydrochloric Acid HCl

Nitric (V) Acid HNO3

Phosphoric (V) Acid H3PO4

Sulfuric (VI) H2SO4

Ethanoic Acid CH3COOH

Writing & Balancing Equations Review

• Reactants on left• Products on right• Arrow is read “yields”• Must include state symbols (s), (l), (g), (aq)• Number of each type of atom on reactants side MUST

equal number of each type of atom on products side (law of conservation of matter)

• Remember your 7 diatomic elements• Ex: Magnesium burns in oxygen to form a white powder

known as magnesium oxide. Write a balanced chemical equation to represent this change.

More Balancing• Write the balanced equations for the following reactions:

• Calcium metal and water yields a solution of calcium hydroxide and hydrogen gas

• Potassium hydroxide is a soluble base that can neutralize the diprotic acid sulfuric acid. The salt formed is aqueous potassium sulfate in water.

• Hydrochloric acid reacts with sodium hydrogencarbonate to form carbon dioxide, water, and sodium chloride

• Solid ammonium dichromate (NH4)2Cr2O7 decomposes into chromium (III) oxide, water vapor, and nitrogen gas.

The Atom Economy• As we are becoming more aware of environmental issues, “green chemists” are concerned with developing methods to create synthetic substances while conserving raw materials and producing less toxic emissions.• The concept of atom economy was developed by Professor Barry Trost of Stanford University to look at the efficiency of chemical reactions• In an ideal process an atom economy of 100% would indicate

that no atoms were wasted.

The Atom Economy

• What is the atom economy for making hydrogen by reacting coal with steam?

C(s) + 2H2O(g)    →    CO2(g) + 2H2(g)

This indicates that this process is not very efficient.

HOMEWORK• Read pp 1 – 11 with ALL Activity & Quick Questions

Completed. • (NOTE: You must label Activity or Quick Questions with

Page Numbers) • Keep these questions organized. This is part of your

study tools.