The document discusses alkanes and their reactions, specifically combustion and free radical substitution. It begins by introducing alkanes and their properties. Alkanes are unreactive due to having nonpolar bonds with similar electronegativity. They react when provided a strong energy source through heating or UV light. Combustion of alkanes is an exothermic reaction important for energy production. Free radical substitution involves a three step mechanism of initiation, propagation, and termination. Initiation uses UV light or heat to break bonds homolytically. Propagation involves radical reactions perpetuating the chain. Termination occurs when radicals combine into stable molecules, ending the chain reaction.
Introduction to benzene, orbital picture, resonance in benzene, Huckel‟s rule
Reactions of benzene - nitration, sulphonation, halogenation- reactivity, Friedel- Craft‟s alkylation- reactivity, limitations, Friedel-Craft‟s acylation.
Substituents, effect of substituents on reactivity and orientation of mono substituted benzene compounds towards electrophilic substitution reaction.
This is the presentation about alkanes including its properties ,nomenclature,preparation,reaction and its importance to our everyday lives.
This is very important to education. It is used during our reports in order to learn.
Thus by opening this document you can learn about naming alkanes and cycloalkanes. It is also helpful in preparation in order to identify its importance. I hope that all of you will download this presentation.
Bonding of Carbon. Hydrocarbons. Constitutional Isomerism and Branched-Chain Alkanes. Uses of Alkanes and Cycloalkanes. Substitution Reactions of Alkanes. Geometric Isomerism. Addition Reactions of Alkenes. Substitution Reactions of Aromatic Hydrocarbons.
Synthetic Fiber Construction in lab .pptxPavel ( NSTU)
Synthetic fiber production is a fascinating and complex field that blends chemistry, engineering, and environmental science. By understanding these aspects, students can gain a comprehensive view of synthetic fiber production, its impact on society and the environment, and the potential for future innovations. Synthetic fibers play a crucial role in modern society, impacting various aspects of daily life, industry, and the environment. ynthetic fibers are integral to modern life, offering a range of benefits from cost-effectiveness and versatility to innovative applications and performance characteristics. While they pose environmental challenges, ongoing research and development aim to create more sustainable and eco-friendly alternatives. Understanding the importance of synthetic fibers helps in appreciating their role in the economy, industry, and daily life, while also emphasizing the need for sustainable practices and innovation.
Introduction to benzene, orbital picture, resonance in benzene, Huckel‟s rule
Reactions of benzene - nitration, sulphonation, halogenation- reactivity, Friedel- Craft‟s alkylation- reactivity, limitations, Friedel-Craft‟s acylation.
Substituents, effect of substituents on reactivity and orientation of mono substituted benzene compounds towards electrophilic substitution reaction.
This is the presentation about alkanes including its properties ,nomenclature,preparation,reaction and its importance to our everyday lives.
This is very important to education. It is used during our reports in order to learn.
Thus by opening this document you can learn about naming alkanes and cycloalkanes. It is also helpful in preparation in order to identify its importance. I hope that all of you will download this presentation.
Bonding of Carbon. Hydrocarbons. Constitutional Isomerism and Branched-Chain Alkanes. Uses of Alkanes and Cycloalkanes. Substitution Reactions of Alkanes. Geometric Isomerism. Addition Reactions of Alkenes. Substitution Reactions of Aromatic Hydrocarbons.
Synthetic Fiber Construction in lab .pptxPavel ( NSTU)
Synthetic fiber production is a fascinating and complex field that blends chemistry, engineering, and environmental science. By understanding these aspects, students can gain a comprehensive view of synthetic fiber production, its impact on society and the environment, and the potential for future innovations. Synthetic fibers play a crucial role in modern society, impacting various aspects of daily life, industry, and the environment. ynthetic fibers are integral to modern life, offering a range of benefits from cost-effectiveness and versatility to innovative applications and performance characteristics. While they pose environmental challenges, ongoing research and development aim to create more sustainable and eco-friendly alternatives. Understanding the importance of synthetic fibers helps in appreciating their role in the economy, industry, and daily life, while also emphasizing the need for sustainable practices and innovation.
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http://sandymillin.wordpress.com/iateflwebinar2024
Published classroom materials form the basis of syllabuses, drive teacher professional development, and have a potentially huge influence on learners, teachers and education systems. All teachers also create their own materials, whether a few sentences on a blackboard, a highly-structured fully-realised online course, or anything in between. Despite this, the knowledge and skills needed to create effective language learning materials are rarely part of teacher training, and are mostly learnt by trial and error.
Knowledge and skills frameworks, generally called competency frameworks, for ELT teachers, trainers and managers have existed for a few years now. However, until I created one for my MA dissertation, there wasn’t one drawing together what we need to know and do to be able to effectively produce language learning materials.
This webinar will introduce you to my framework, highlighting the key competencies I identified from my research. It will also show how anybody involved in language teaching (any language, not just English!), teacher training, managing schools or developing language learning materials can benefit from using the framework.
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Operation “Blue Star” is the only event in the history of Independent India where the state went into war with its own people. Even after about 40 years it is not clear if it was culmination of states anger over people of the region, a political game of power or start of dictatorial chapter in the democratic setup.
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June 3, 2024 Anti-Semitism Letter Sent to MIT President Kornbluth and MIT Cor...Levi Shapiro
Letter from the Congress of the United States regarding Anti-Semitism sent June 3rd to MIT President Sally Kornbluth, MIT Corp Chair, Mark Gorenberg
Dear Dr. Kornbluth and Mr. Gorenberg,
The US House of Representatives is deeply concerned by ongoing and pervasive acts of antisemitic
harassment and intimidation at the Massachusetts Institute of Technology (MIT). Failing to act decisively to ensure a safe learning environment for all students would be a grave dereliction of your responsibilities as President of MIT and Chair of the MIT Corporation.
This Congress will not stand idly by and allow an environment hostile to Jewish students to persist. The House believes that your institution is in violation of Title VI of the Civil Rights Act, and the inability or
unwillingness to rectify this violation through action requires accountability.
Postsecondary education is a unique opportunity for students to learn and have their ideas and beliefs challenged. However, universities receiving hundreds of millions of federal funds annually have denied
students that opportunity and have been hijacked to become venues for the promotion of terrorism, antisemitic harassment and intimidation, unlawful encampments, and in some cases, assaults and riots.
The House of Representatives will not countenance the use of federal funds to indoctrinate students into hateful, antisemitic, anti-American supporters of terrorism. Investigations into campus antisemitism by the Committee on Education and the Workforce and the Committee on Ways and Means have been expanded into a Congress-wide probe across all relevant jurisdictions to address this national crisis. The undersigned Committees will conduct oversight into the use of federal funds at MIT and its learning environment under authorities granted to each Committee.
• The Committee on Education and the Workforce has been investigating your institution since December 7, 2023. The Committee has broad jurisdiction over postsecondary education, including its compliance with Title VI of the Civil Rights Act, campus safety concerns over disruptions to the learning environment, and the awarding of federal student aid under the Higher Education Act.
• The Committee on Oversight and Accountability is investigating the sources of funding and other support flowing to groups espousing pro-Hamas propaganda and engaged in antisemitic harassment and intimidation of students. The Committee on Oversight and Accountability is the principal oversight committee of the US House of Representatives and has broad authority to investigate “any matter” at “any time” under House Rule X.
• The Committee on Ways and Means has been investigating several universities since November 15, 2023, when the Committee held a hearing entitled From Ivory Towers to Dark Corners: Investigating the Nexus Between Antisemitism, Tax-Exempt Universities, and Terror Financing. The Committee followed the hearing with letters to those institutions on January 10, 202
The Roman Empire A Historical Colossus.pdfkaushalkr1407
The Roman Empire, a vast and enduring power, stands as one of history's most remarkable civilizations, leaving an indelible imprint on the world. It emerged from the Roman Republic, transitioning into an imperial powerhouse under the leadership of Augustus Caesar in 27 BCE. This transformation marked the beginning of an era defined by unprecedented territorial expansion, architectural marvels, and profound cultural influence.
The empire's roots lie in the city of Rome, founded, according to legend, by Romulus in 753 BCE. Over centuries, Rome evolved from a small settlement to a formidable republic, characterized by a complex political system with elected officials and checks on power. However, internal strife, class conflicts, and military ambitions paved the way for the end of the Republic. Julius Caesar’s dictatorship and subsequent assassination in 44 BCE created a power vacuum, leading to a civil war. Octavian, later Augustus, emerged victorious, heralding the Roman Empire’s birth.
Under Augustus, the empire experienced the Pax Romana, a 200-year period of relative peace and stability. Augustus reformed the military, established efficient administrative systems, and initiated grand construction projects. The empire's borders expanded, encompassing territories from Britain to Egypt and from Spain to the Euphrates. Roman legions, renowned for their discipline and engineering prowess, secured and maintained these vast territories, building roads, fortifications, and cities that facilitated control and integration.
The Roman Empire’s society was hierarchical, with a rigid class system. At the top were the patricians, wealthy elites who held significant political power. Below them were the plebeians, free citizens with limited political influence, and the vast numbers of slaves who formed the backbone of the economy. The family unit was central, governed by the paterfamilias, the male head who held absolute authority.
Culturally, the Romans were eclectic, absorbing and adapting elements from the civilizations they encountered, particularly the Greeks. Roman art, literature, and philosophy reflected this synthesis, creating a rich cultural tapestry. Latin, the Roman language, became the lingua franca of the Western world, influencing numerous modern languages.
Roman architecture and engineering achievements were monumental. They perfected the arch, vault, and dome, constructing enduring structures like the Colosseum, Pantheon, and aqueducts. These engineering marvels not only showcased Roman ingenuity but also served practical purposes, from public entertainment to water supply.
Read| The latest issue of The Challenger is here! We are thrilled to announce that our school paper has qualified for the NATIONAL SCHOOLS PRESS CONFERENCE (NSPC) 2024. Thank you for your unwavering support and trust. Dive into the stories that made us stand out!
CLASS 11 CBSE B.St Project AIDS TO TRADE - INSURANCE
Reactions of Alkanes.pptx.pdf
1. Alkanes and their Reactions
13-Apr-15
Objective:
Be able to write equations for the combustion of alkanes
Be able to describe the free radical substitution of Alkanes
3. Reactions of Alkanes
At room temperature the alkanes are very
unreactive.
Why?
Hint:
Electronegativity and
enthalpy
4. Alkanes are unreactive because:
The C-C and C-H bonds involve an equal sharing of
electrons. The electronegativities are similar and therefore
the bonds are not polar. This makes them less susceptible
to attack from many organic molecules.
1. Electronegativity
2. Bond Enthalpy
Alkanes are relatively simple molecules that contain only
single C-C and C-H bonds. These bonds have a relatively
high bond enthalpy. So they only react in the presence of a
strong energy source.
5. Heating Alkanes
In the absence of air
In a plentiful supply
of air
Cracking Combustion
A form of thermal
decomposition where large
molecules are broken down
into smaller more useful.
The burning of a
fuel to create
thermal energy.
6. Why is the combustion of alkanes so
important to our life?
1. Generating electricity
2. Fuel fires
3. Central heating
4. Cooking
5. transport
It is an exothermic reactions.
Energy is transferred from chemical energy
to thermal energy that we can use.
7. Alkanes are often used as fuels because they
release large amounts of energy on combustion.
• The products of the combustion of alkanes
contain relatively strong bonds (C=O and O-H)
that release a lot of energy on their formation.
Combustion
8. Which alkanes do we use for combustion?
Methane Propane Butane
• Methane 🡪 butane are colourless gases
• Propane and butane can be condensed under
pressure
• Alkanes containing 5-19 carbons are colourless
liquids
• Alkanes with 20+ carbons are colourless waxy
solids
1. Why do we use these alkanes for combustion?
2. Why is propane and butane used more than methane?
3. Suggest why we do not use ethane for combustion
9. Candles are made from alkanes that generally
contain 20-25 carbons
if this is true
why does the
whole candle
not combust?
10. complete Incomplete
Burns in a plentiful supply
of oxygen
Burns in a limited supply
of oxygen
Creates carbon dioxide (a
greenhouse gas)
Creates carbon monoxide
Very energy efficient Low energy efficiency
Creates soot (carbon)
CH4
+ 2O2
🡪 CO2
+ 2H2
O CH4
+ 1.5O2
🡪 CO + 2H2
O
CH4
+ O2
🡪 C + 2H2
O
11. Substitution Reaction
CH4
+ Br2
🡪 CH3
Br + HBr
1. UV light is needed to start a substitution
reaction
2. The bromine atom actually takes the place of
a Hydrogen atom.
3. The molecule formed is called
bromomethane
Why is this called an substitution reaction?
Recap from GCSE:
12. Bond fission: breaking bonds
When you break bonds there are 2 ways the
electrons can be shared out
1. Homolytic fission
2. Heterolytic fission
Same/destruction
different/destruction
13. Homolytic fission
• When the breaking of a covalent bond leads to
both atoms having an equal share of
electrons.
• Formation of atoms with unbonded electons=
free radicals
• Draw dot and cross diagrams to represent
what is happening
Cl-Cl 🡪 Cl◦ +Cl◦
14. Free radicals produced from homolytic
fission
1. They are not charged
2. But extremely reactive
15. Heterolytic fission
• Unequal sharing of electrons
• Results in two charged particles
• Covalent bond will already have a degree of
polarity
H-Cl 🡪 H+
+ Cl-
16. Summary Halogenation of Alkanes
• Requires ultraviolet (UV) radiation
• Requires 300o
C
• Bonds break by homolytic fission, which forms
free radicals – an atom with an unpaired
electron
• The radicals substitute
• There is a three stage mechanism for the
reaction
17. Step 1: Initiation
• A chlorine molecule, Cl-Cl is broken by
homolytic fission.
– UV radiation provides the energy for this to
happen
Cl-Cl 🡪 Cl
.
+ Cl
.
• The rest of the reaction requires no more
energy to be added, as the chlorine radical
attack the methane (or other alkane)
18. Step 2: Propagation
• Methane reacts with the chlorine radical
– A single C-H bond is broken by homolytic fission,
forming a
.
CH3
radical
– HCl is also formed
CH4
+ Cl
.
🡪 .
CH3
+ HCl
• The methyl radical then reacts with a chlorine
molecule, forming chloromethane and
another chlorine radical.
.
CH3
+ Cl2
🡪 CH3
Cl + Cl
.
19. • In halogenation of alkanes, the halogen undergoes
homolytic fission to produce two free radical chlorines
• These free radicals attack the C-H bonds in the alkane
• This produces a methyl free radical group which can
continue to react with chlorine
• Which produces another free radical. This recycling of free
radicals produces a self-propogating chain reaction
Step 2: Propagation
20. • Propagation reactions are rapid.
• This is a chain reaction, as each time a
chloromethane molecule is formed, another
chlorine radical is formed to react with
another methane molecule
• Therefore the reaction will continue until no
chlorine is left
21. Step 3: Termination
• Two radicals combine to form a molecule
• There are three possibilities for the reaction
between chlorine and methane:
Cl
.
+ Cl
.
🡪 Cl2
.
CH3
+ Cl
.
🡪 CH3
Cl
.
CH3
+ .
CH3
🡪 C2
H6
• This stage removes radicals, thus terminating the
reaction.
• The propagation step would have happened
22. Further Reactions of Chloromethane
• Chloromethane can undergo further reactions
with chlorine radicals, forming:
–
–
–
24. Task
• Show the mechanism for the bromination of
methane.
– Include all three steps!
25. Which stage of substitution reactions
do the following describe?
Two free radicals collide and produce
a molecule
UV light provides the energy needed for
homolytic fission of a Chlorine molecule
A free radical reacts with molecule to
crate another free radical
What order do the stages of the
mechanism?
26.
27. Which stage of substitution reactions
do the following describe?
Two free radicals collide and produce
a molecule
UV light provides the energy needed for
homolytic fission of a Chlorine molecule
A free radical reacts with molecule to
crate another free radical
What order do the stages of the
mechanism?
28. Draw curly arrow and dot and cross
diagrams for the following reactions
H-Br 🡪 hydrogen and bromine ions
Br-Br 🡪 bromine free radicals