Categorie: Tutti - formulas - reactions - ratios

da Baig Sohail manca 1 anno

181

SCH3U0

The study of stoichiometry involves understanding the quantitative relationships in chemical reactions, focusing on the use of moles to measure substances. Core concepts include determining the number of moles through formulas that relate mass, molar mass, and Avogadro’

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Floating topic

Combined Gas Law: (P1V1)/T1 = (P2V2)/T2

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Solutions & Solubility

Stoich and Solutions
Expanding to include concentrations and volume into regular stoichiometry problems
Formulas:

n = m/M

c1v1 = c2v2

C = n/v

Chemical Equations
3) Net Ionic Equation

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

2) Ionic Equation

Each Ion separated

1) Balanced chemical equation
Creating Solutions

Two liquids mix, one solid (precipitate)

Dilutions

Dilution Formula: C1V1 = C2V2

Diluting a stock solution of HCL(aq)

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

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

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

- Obtain 1000mL volumetric flask

From a solid

Creating 500 mL of a mol/L of NaOH

- Obtain 500mL volumetric flask

- Add 250 mL or more to reach the fill line

- Cap and invert to mix

- add approx. 250 mL of distilled water to flask

- Place measured amount of solid in flask

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

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

Percentage Concentrations
Other Concentrations

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

Used for various purposes in industries that use different standards
3 types

Mass/Volume % (m/v)

Volume/Volume % (v/v)

Mass/Mass % (m/m)

Components of a solution
Solvent

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

Solute

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

Characteristics of solutions
Particles cannot be clearly seen

Cannot be filtered

Unsaturated Solution - Solute less than fully saturated
Saturated Solution - No more solute can be dissolved at the given temperature
Polar molecules dissolve in polar non-polar dissolve in non-polar
May be slightly coloured
Transparent (Clear if aqueous)
Homogenous Mixture

- Can be separated into components - Looks the same throughout

Gases & Atmospheric Chemistry

Dalton's Law of Partial Pressure
The pressure that each gas in a mixture exerts is it's partial pressure
Partial Pressure is used to determine the concentration or fraction in a mixture

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

Gas Stoich
Expanding to include pressure and temperature into regular stoichiometry problems.

Formulas needed:

The "Ideal" Gas Law
SATP is Standard Ambient Temperature and Pressure --------------- SATP = 298K and 100 kPa
STP is Standard Temperature and Pressure STP = 273K and 101.3 kPa
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

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

P1/T1 = P2/T2

Charles' Law
Temperature

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

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

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

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

Boyle's Law
The volume of a gas varies inversely with with pressure (at a constant temp)

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

P1V1 = P2V2

Kinetic Molecular Theory
Pressure = force/area

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

Gas particles are in constant motion and have perfectly elastic collisions

(in closed systems) Multiple collisions increase pressure

Background/Intro
Gasses are the only compressible state
States of substances depend on the forces between the particles

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

Chemical Trends & Bonding

Bonding
Polar Covalent Bond

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

An uneven distribution of charges due to unequal sharing of electrons

Intermolecular

Ionic Bonds

Intramolecular

Covalent Bonds

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

Bonding Capacity

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

Groups (1-3) = # of group

related to # of valence electrons

Lewis-Dot Bonding/Structures
Periodic Trends
PERIODIC LAW: When elements are arranged by increasing atomic number, they fall into categories with similar chemical/physical properties
Atomic Radius

Increases 🡳 and 🡰

Factors affecting size

Strength of attraction of valence electrons

Shielding effect - multiple energy levels

# of shells/energy levels

Half of distance from nucleus to valence

Stoichiometry

Stoich Problems
Molar Ratio: Moles of unknown/moles of known
Percent Yield

Tells us how 'efficient' a reaction was

Actual Yield: Actual amount of product formed

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

% Yield = Actual/Theoretical

Limiting/Excess Reagent

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

Given both reactants' masses

Find mass of either reactant(s) or products

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

Empirical & Molecular Formula
Molecular

Actual ratio for formula of a compound

Empirical or 'Simplest'

Formula for a compound in the smallest whole number ratio

Percent Composition (%)
% composition = (Mass of individual element/total mass) x 100
Moles
Formulas

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

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

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

**Avogadro's Constant**

*The unit used to measure amounts of any substance.

Chemical Reactions

Nomenclature
Polyatomics and diatomic molecules
Balancing Chemical Equations
Set of rules for naming compounds
Types of Reactions
Combustion

- Burning of hydrocarbons - Complete combustion produces CO2 and H2O

Double Displacement

Neutralization Reactions

Base + Acid 🡲 Salt + Water

Precipitation Reaction

Always has a solid and an aqueous product

Single Displacement

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

Decomposition

- Reactant broken down into 2 or more products

Synthesis

- 2 different molecules/atoms combine to produce a compound