SCH3U0

Chemical Reactions

Types of Reactions

Synthesis

- 2 different molecules/atoms
combine to produce a compound

Decomposition

- Reactant broken down into
2 or more products

Single Displacement

- Element reacts with a compound
and displaces the 2nd element to
form a new compound and an element

Double Displacement

Precipitation Reaction

Always has a solid and
an aqueous product

Neutralization Reactions

Base + Acid 🡲 Salt + Water

Combustion

- Burning of hydrocarbons
- Complete combustion produces CO2 and H2O

Nomenclature

Set of rules for
naming compounds

Balancing Chemical Equations

Polyatomics and diatomic molecules

Stoichiometry

Moles

*The unit used to measure
amounts of any substance.

1 Mole (or "mol) is
~6.02 x 10^23

**Avogadro's Constant**

Formulas

# of moles = mass(g)/Molar mass(g/mol)
or n=m/M

# of moles = # of entities/Avogadro's constant
or n = N/Na

Percent Composition (%)

% composition =
(Mass of individual element/total mass) x 100

Empirical & Molecular Formula

Empirical or 'Simplest'

Formula for a compound in the
smallest whole number ratio

Molecular

Actual ratio for formula
of a compound

Stoich Problems

Find mass of either reactant(s) or products

Use formulas:
(n = m/M) and (n = N/Na)

Limiting/Excess Reagent

Given both reactants' masses

To determine which reactant
will be consumed first

Divide moles of each reactant
by coefficient of reactant to find # of "cycles"

Reactant with more cycles is excess
reactant with less is limiting

Percent Yield

Tells us how 'efficient' a reaction was

Theoretical Yield:
Calculated or 'expected' amount
of product formed

% Yield = Actual/Theoretical

Actual Yield:
Actual amount
of product formed

Molar Ratio:
Moles of unknown/moles of known

Chemical Trends & Bonding

Periodic Trends

Atomic Radius

Half of distance from nucleus to valence

Factors affecting size

# of shells/energy levels

Shielding effect -
multiple energy levels

Strength of attraction
of valence electrons

Increases 🡳 and 🡰

Bonding

Lewis-Dot Bonding/Structures

Bonding Capacity

related to # of valence electrons

Groups (1-3) = # of group

Groups (4-8) = 8 - # of valence electrons

Intramolecular

Covalent Bonds

1. Hydrogen bonding
2. Dipole-dipole
3. London forces

Intermolecular

Ionic Bonds

Polar Covalent Bond

An uneven distribution of charges
due to unequal sharing of electrons

For a molecule to be polar,
it must be:
- Containing a polar bond
- Molecule does not have symmetry

Gases & Atmospheric Chemistry

Background/Intro

States of substances depend
on the forces between the particles

If the forces are strong - solid
If the forces are weak - Liquid or gas

Gasses are the only
compressible state

Kinetic Molecular Theory

Gas particles are in constant
motion and have perfectly elastic
collisions

(in closed systems)
Multiple collisions increase pressure

Pressure = force/area

Can be measured in:
Kilopascals (kPa)
Pascals (Pa)
Atmospheres (atm)
Millimeters of Mercury (mmHg)
Torrs

Boyle's Law

The volume of a gas varies
inversely with with pressure
(at a constant temp)

P1V1 = P2V2

Shampoo bottle exploded
on plane -
Altitude increases, pressure decreases,
making the volume increase

Charles' Law

The volume of a fixed amount
of gas varies directly with
the temperature of the gas
(constant pressure)

V1/T1 = V2/T2

Calculations always done in Kelvin

Temperature

The more kinetic energy the particles
have, the higher the temperature

Temperature recorded in 3 ways:
Celsius (C)
Fahrenheit (F)
Kelvin (K)
K = C + 273

Absolute Zero:
Theoretical Temperature where
all matter would freeze.
Absolute Zero is "-273 C" or "0 K"

Gay-Lussac Law

The pressure of a gas varies
directly with the temperature
of the gas.
(At a constant volume)

P1/T1 = P2/T2

The "Ideal" Gas Law

Pressure multiplied by volume
is equal to the number of moles
times the universal gas constant
and temperature

PV = nRT

R = 8.31 kPa*L/mol*K

STP is
Standard Temperature and Pressure
STP = 273K and 101.3 kPa

SATP is
Standard Ambient
Temperature and Pressure
---------------
SATP = 298K and 100 kPa

Gas Stoich

Expanding to include pressure and temperature into regular stoichiometry problems.

Formulas needed:

PV = nRT

Dalton's Law of Partial Pressure

Partial Pressure is used to
determine the concentration
or fraction in a mixture

P(total) = P1 + P2 + P3...

The pressure that each gas
in a mixture exerts is it's partial pressure

Solutions & Solubility

Characteristics of solutions

Homogenous Mixture

- Can be separated into components
- Looks the same throughout

Transparent (Clear if aqueous)

May be slightly coloured

Polar molecules dissolve in polar
non-polar dissolve in non-polar

Saturated Solution -
No more solute can be dissolved
at the given temperature

Unsaturated Solution -
Solute less than fully saturated

Particles cannot be clearly seen

Cannot be filtered

Components of a solution

Solute

Substance being dissolved into a solvent
(sugar, salt, etc.)

Solvent

Medium in which solute is being dissolved
(water, alcohol, etc.)

Percentage Concentrations

3 types

Mass/Mass % (m/m)

Volume/Volume % (v/v)

Mass/Volume % (m/v)

Used for various purposes in industries
that use different standards

Other Concentrations

ppm (parts per million) =
- 1 g/m3
- 1 g/1000L
- 1 mg/L
- 1 mg/kg

Concentration

Molar Concentration Formula

Concentration = # of moles/volume
or (c = n/v)

How much of solute in a solution
in terms of moles per litre(mol/L) or "M".

Creating Solutions

From a solid

Creating 500 mL of a
mol/L of NaOH

- Place measured amount of solid in flask

- add approx. 250 mL of
distilled water to flask

- Cap and invert to mix

- Add 250 mL or more to reach the fill line

- Cap and invert to mix

- Obtain 500mL volumetric flask

Dilutions

Diluting a stock solution of HCL(aq)

- Obtain 1000mL volumetric flask

- Add approx. 500 mL of distilled water
to volumetric flask

- Measure and add 250 mL of HCL (aq)
to volumetric flask

- Cap and invert to mix

- Add 250mL or more of distilled water
up to the fill line

- Cap and invert to mix

Dilution Formula:
C1V1 = C2V2

Precipitation Reaction

Two liquids mix, one solid (precipitate)

Chemical Equations

1) Balanced chemical equation

2) Ionic Equation

Each Ion separated

3) Net Ionic Equation

'Spectator Ions' removed
Spectator Ions are ions that don't
appear on both sides of the equation

Stoich and Solutions

Formulas:

C = n/v

c1v1 = c2v2

n = m/M

Expanding to include concentrations
and volume into regular stoichiometry problems

Floating topic