Energy - Uses and Types

Def. The capacity to do work is measured in Joules (J).

Types of energy can be grouped into two general types, potential and kinetic, which can be further categorized into heat, light, motion, electrical, chemical, or gravitational energy.

• Potential - refers to stored energy that varies upon the relative position of various parts of a system. e.g. battery, compressed spring or a steel ball raised above the ground.

• Kinetic - refers to the working energy that an object has because of its motion. e.g. man running, anything moving, windmill spinning

Energy can also be referred to as renewable or non-renewable. Renewable energy is energy that can be replenished within the time it is used or the lifetime of a human, while nonrenewable energy cannot.

Law Of Conservation

1. The total energy in a system remains constant or conserved over time.

2. Energy can be neither created nor destroyed; rather, it can only be transformed or transferred from one form to another.

Energy consumption is the total amount of energy used/transformed in a given process and is either defined as direct or indirect.

• Direct - energy used/transformed when in contact with the consumer. e.g. lap top light and sound energy

• Indirect - energy used in the manufacturing and servicing of the product. e.g. a fossil fuel with stored potential energy or electricity used in machinery.

Reactions - Endo and Exo

Enthalpy, H of a system (reactants including aqueous solution) is quantitative measure of the potential energy stored in a system. It cannot be measured directly. (the energy content of the system)

The enthalpy change of a system is the heat energy exchanged with its surroundings (at constant pressures).

Exothermic reactions release energy (usually heat) from the systems to the surroundings the temperature of the surroundings increases.

Endothermic reactions absorb energy from the surroundings, taken into the system. The temperature of the surroundings decreases so they get cold. E.g. Thermal decomposition, photosynthesis, some electrolysis, etc.

!You can show that some endo and exothermic reactions are reversible!

• If a reaction is showed that it as an exothermic reaction in the forward reaction, the reverse direction is an endothermic reaction. Therefore, you can calculate the energy change(Enthalpy change) in a forward/reverse reaction.

Endothermic or Exothermic Equation?

• Heat is in the products means that it is an exothermic reaction. If heat is in the reactants then it is endothermic.

• Energy being in products as a (+) means it is exothermic

• Change in enthalpy as (-) is exothermic

systems → surroundings

surroundings → systems

Catalyst and Energy Transfer

One way of reducing the energy used in a chemical reaction is to use a catalyst. Catalysts allow reactions to take place at a faster rate, and often at a lower temperature too. Catalyst are substances that increase the

• Platinum

Energy Profile Diagrams Marking Key

• Energy Profile Diagram for Endothermic/Exothermic Reaction

• Enthalpy/Energy (y-axis) Progress of Reaction/Time (x-axis)

• Reactants (equation), Products (equation)

• Transition state 1 mark

• Activation Energy (En)

• Hill must be higher than products line

• Enthalpy Change and Must write down enthalpy change (kj)

• Dotted line with rulers

Fossil Fuels - Formation and Distillation

A hydrocarbon-based fuel containing chemical potential energy, originally living organic matter (e.g. phytoplankton, plants, photosynthetic organisms) from millions of years ago found in sedimentary rock.

Fossil fuels are commonly burned to provide heat for direct use, to power engines, or to generate electricity.

Formation of Fossil Fuels

Process of Crude Oil

1. Microscopic, photosynthetic phytoplankton/organisms transform the sun’s light energy into stored chemical energy within glucose molecules.

2. Over an extended period of time (millions of years ago), volcanic activity releases high concentrations of carbon dioxide into the atmosphere. Carbon dioxide is needed to create glucose and oxygen.

3. When the organic phytoplankton/organisms die, their remains sink to the bottom of the ocean, where it is anoxic and accumulates in layers.

4. Rapid burial of the phytoplankton by sedimentation occurs repeatedly. Layers of sediment, including mud, sand, and organic material, accumulate on top of the phytoplankton.

5. The weight of these layers causes compression on the lowermost part of the organic material, which increases the pressure and temperature.

6. The heat and pressure from the earth’s mantle warm the phytoplankton.

7. Once the buried layers reach sufficient depth, the high temperatures and pressure transform the organic material into the fossil fuel known as crude oil.

Process of Natural Gas

1. When the temperatures are too high, organic material transforms into a natural gas.

2. Carbon changes form from glucose to a fossil fuel component.

Process of Coal

1. Millions of years ago, giant plants died in swampy forest areas.

2. Over an extended period of time (millions of years), the dead fallen plants are covered/buried by sediment and become submerged.

3. This process repeats as more layers accumulate and sediment.

4. The cumulative weight of layers upon layers eventually leads to high pressures.

5. Heat energy from the Earth’s mantle interacts with the lower sediment layers and creates sedimentary rock.

6. Heat and pressure then transform the organic material into coal.

Separating Crude Oil - Fractional Distillation

Boiling points are used to separate compounds into fractions. Compounds are what crude oil/petroleum is consisted of.

Fractions are groups of hydrocarbon molecules with similar carbon chain lengths, properties, and boiling points. Each fraction has a different use.

The bottom of the fractionating column. At the bottom of the fractionating column, the heavier long-chain hydrocarbons end up reaching their boiling/melting point and are able to be delivered out as a ‘fraction’.

The Process of Fractional Distillation

1. The crude oil is heated in a furnace to over 400 degrees Celsius. At this temperature, most of the hydrocarbons in the crude oil mixture boil and turn into a gaseous state/vapor.

2. The mixture of hot hydrocarbon gases passes into a fractionating column which is hotter at the bottom and cooler at the top.

3. The hot gases/vapors rise up the column. Once the temperature of the column falls below the boiling point of hydrocarbon in the mixture, it is no longer hot enough for the hydrocarbon to stay in gaseous form and condense. A group of compounds with similar boiling points exits the fractionating column.

4. The longer chain hydrocarbons(heavier) have a higher boiling point and condense towards the bottom of the column where it is hotter and leaves the column. The shorter chain(lighter) hydrocarbons have a lower boiling point and remain as gases higher up, only condensing once a lower temperature is reached near the top of the column.

5. Very short-chain hydrocarbons have a boiling point so low they do not condense within the fractionating column and are separated from the top of the column as gases.

Simple Distillation VS Fractional Distillation

Simple distillation is a method of separation to separate a solvent from a solution. E.g. producing water from a salt solution. The dissolved solute(Copper Sulfate) has a much higher boiling point than the solvent(water). When the solution is heated, solvent vapor evaporates from the solution. The gas moves away and is cooled and condensed. The remaining solution becomes more concentrated in solute as the amount of solvent in it decreases.

Example Experiment: Copper Sulfate solution (water) + Ethanol

• Thermometer right above the liquid to measure the gas

• At no time does the thermometer touch the glass

• Separating ethanol at 78*C

• Water and ethanol are both clear colorless solutions but ethanol is flammable

• Physical property separation

• Combustion of ethanol is a chemical (flammability)

Naming Alkanes

1. Find the longest carbon chain - establish what alkane prefix

2. Find which side to start from

3. Find what groups are attached to the carbons

   1. write which carbon (-) group and then carbon chain prefix

   2. 4-ethyl-2-methyl,Hexane

Types of Fossil Fuels

There are 3 main types of fossil fuels; coal, crude oil (petroleum), and natural gases.

Coal - source for electricity and industrial processes.

Crude Oil - a raw material for producing fuels like gasoline, diesel, jet fuel and etc.

Natural Gas - electricity generation, heating and fuel for other industrial processes.

Greenhouse Effect - Gases and Enhanced

Def. The greenhouse effect is a process that occurs when certain gases in the earth’s atmosphere absorb and re-emit infrared radiation, which traps heat within the atmosphere, warming the planet’s surface and making it suitable for organisms to live in. The greenhouse effect can be both contributed and enhanced.

The Greenhouse Effect Process

1. The sun emits energy in the form of visible light that consists of electromagnetic radiation. Some of the solar radiation passes the Earth’s atmosphere and reaches the planet’s surface.

2. When solar radiation reaches the earth’s surface, some of it is absorbed as infrared radiation while some of is is reflected back to space.

3. Certain gases in the atmosphere known as greenhouse gases have the property of absorbing and emitting infrared radiation. They act as a natural blanket by trapping some of the heat that escapes into space. This happens because greenhouse gases absorb infrared and gain vibrational energy which increases kinetic energy and therefore the temperature of the earth increases.

4. The greenhouse effect helps maitain a relatively table temperature on Earth. The process of absorbing and remitting solar energy creates a balance that allows the Earth to maintain an average temperature of 15 degree Celsius.

The Enhanced Greenhouse effect

• Enhanced greenhouse effect (climate change or global warming) is where a greater concentration of greenhouse gases in our atmosphere traps additional heat from the sun and raises the Earth's surface temperature. This is commonly the result of human activity; deforestation, agricultural practices, burning of fossil fuels for transportation, etc.

• Exam question: greenhouse effect of ENHANCED greenhouse effect Draw, label, and annotate diagram (the label is 1 or 2 words, annotate mean extended points)

• the greenhouse effect is enhanced because human activities significantly increase the concentration of greenhouse gases in the atmosphere. The increase in concentration is primarily done by deforestation, burning fossil fuels, and industrial processes. This enhanced greenhouse effect leads to more heat being trapped in the atmosphere causing the planet to warm which is known as global warming.

Local effects can be observed when the enhanced greenhouse effect leads to increased temperatures. Some species can become endangered or extinct because they cannot tolerate the increase in temperature.

Average global temperature increases that leads to global climate change and leads to extreme weather conditions like droughts and floodings.

Organic Chemistry

Def. Organic Chemistry is the study of the structure, properties, composition, reactions, and preparation of carbon-containing compounds. Most organic compounds contain carbon and hydrogen, but they may also include any number of other elements (e.g. nitrogen, oxygen, halogens, phosphorus, silicon, and sulfur).

An organic compound is based on carbon atoms, usually contains hydrogen too, and may also contain other non-metal atoms such as oxygen, nitrogen, and sulfur. Properties of organic compounds include: have covalent bonds, have low melting points, have low boiling points, are flammable, are soluble in nonpolar solvents, and are not soluble in water. Polar dissolves Polar. Hydrocarbons are non-polar and water is polar (meaning it is slightly positively and negatively charged on each side).

Bonding of Carbons

Unique bonding of carbons: Carbon has four valence electrons and so forms four covalent bonds. This gives a huge range of possibilities when forming organic compounds. Forms a tetrahedral shape.

Isomers are molecules with the same molecular formula (the same number of atoms and type of atoms) but a different structural arrangement. Therefore they will have a different name.

Empirical Vs Molecular formulas

The empirical formula is the simplest ratio of the atoms present. E.g. CH3

The molecular formula of a compound shows the number of each type of atom present in one molecule of the compound. E.g. C2H6

Skeletal Diagrams

You don’t need to draw but you might need to interpret.

Cycloalkanes and Cycloalkenes

A homologous series of hydrocarbons with the general formula CnH2n and names starting with cyclo- and ending with -ane. They have carbon atoms bonded in rings and contain ONLY single carbon-carbon bonds and so are saturated. They have a different formula from alkanes because there is no extra hydrogens because the carbons are joined together.

The alkenes are a homologous series of hydrocarbons with the general formula CnH2n and names ending -ene. Hydrocarbons are unsaturated meaning they will be more reactive than cycloalkanes and alkanes. This is because of their double bond.

Alkenes with four or more carbon atoms display positional isomerism because the carbon-carbon double bond may appear between different carbon atoms.

Cyclo-alkenes have 2 less hydrogens

Alkynes are a homologous series of hydrocarbons with the general formula CnH2n-2 and the names starting in ending -yne. Contain at least one carbon-carbon triple bond and so are unsaturated. Cyclo-alkynes are possible although very few are stable. Cyclo-alkynes formula is CnH2n-4

Functional Groups and Homologous Series

A functional group is an atom or group of atoms responsible for the typical chemical reactions of a molecule. determines the patterns of reactivity o a homologous series, whereas a carbon chain length determines other properties like melting/boiling points.

A homologous series is a group of molecules with the same functional group but a different number of CH2 groups.

Functional groups (double and triple bonds included) determine the pattern of reactivity (can it easily combust, can it react easily with…) of a homologous series, whereas the carbon chain length determines physical properties (how high or low melting and boiling points).

Alkanes And Isomers

A homologous series of hydrocarbons with the general formula … and names ending with -ane.

Alkanes with four or more carbon atoms display structural isomerism because the carbon chain may be either straight or branched. Pentane and methylbutane are isomers because they have the same number of carbons and hydrogens but they have different names.

In chain isomers, the carbon chain is arranged differently. E.g. hexane and other …

Combustion of Hydrocarbons

Combustion is a rapid reaction between a substance and oxygen that releases heat and light energy.

Complete Combustion Formula

hydrocarbon + oxygen → carbon dioxide +water

Incomplete Combustion occurs when there is a shortage of air(oxygen), and incomplete combustion of hydrocarbons takes place. It has produced carbon dioxide and water while also producing carbon monoxide and/or carbon soot.

(Fuel is a substance that reacts with oxygen to release useful energy (combusts).)

The general formula of combustion (alkanes)

Exam Questions

• Describe the process of fractional distillation and what is a fraction.

• 1 example of each compound that gets delivered in fractional distillation.

• Be able to handwrite the process of the separation of crude oil.

• How many isomers are there for this hydrocarbon ….

• Why are cycloalkenes more reactive than cycloalkanes and alkanes?

• How many isomers are there of butane

• label annotate process of fractional distillation in lab

• recognise the homologous series of hydrocarbons

• combustion word equations - complete and incomplete

• differentiate endothermic and exothermic and identify

• Draw energy profile diagrams to represent

• Show on energy profile diagrams the impact of catalyst and particularly the activation energy.

Solo Objectives and Checklist

• I can state what energy is.

• I can describe what is meant by energy consumption.

• I can explain how energy is used in everyday life.

• I can describe the direct use of energy in everyday life - lightning, heating, fuel etc.

• I can describe how energy is consumed indirectly.

• I can explain how indirect consumption of energy is associated with the production of consumer goods, energy required to build homes and infrastructure, energy for transporting goods and growing food, etc.

• I can compare direct and indirect use of energy in everyday life.

• I can review what is meant by a fossil fuel (coal, crude oil, natural gas).

• I can explain what happens to the levels of CO2 in the atmosphere with the burning of fossil fuels.

• I can describe the greenhouse effect using ideas about energy and radiation:

• I can state what organic chemistry is.

• I can explain how fractional distillation works and how it is used to separate different substances within crude oil.

• I can recognise homologous series of hydrocarbons:

  • alkanes

  • alkenes

  • alkynes

  • cycloalkanes

  • cycloalkenes

• I can state what a functional group is and recognise functional groups of the homologous series above

• I can general formulae to recognise members of homologous series

• I can state what a saturated hydrocarbon is.

• I can state what an unsaturated hydrocarbon is.

• I can write the names of hydrocarbons using the IUPAC naming system for 8 carbons.

• I can describe the molecular, condensed and structural formulae of hydrocarbons with up to 8 carbons.

• I can name hydrocarbons from diagrams

• I can define viscosity, volatility and flammability in relation to hydrocarbons

• I can describe the trends in physical properties of hydrocarbons.

• I can state what is meant by an endothermic and exothermic reaction.

• I can describe the energy changes that occur during endothermic and exothermic reactions using pos/neg

• I can use the terms systems and surroundings to relate the energy transfer during a reaction.

• I can contrast the difference between endothermic and exothermic reactions in terms of temperature change and energy transfer

• I can define and describe the activation energy as the energy required for reactants to react

• I can state the key features of a catalyst

• I can describe how a catalyst speeds up a chemical reaction

• I can draw energy profile diagrams

• I can identify exothermic or endothermic reactions

• I can use data from reactions to compare fuels