The document defines oxidation and reduction as well as oxidizing and reducing agents. It explains that oxidation is the loss of electrons or gain of oxygen, while reduction is the gain of electrons or loss of oxygen. Oxidizing agents cause oxidation by accepting electrons, while reducing agents cause reduction by donating electrons. Redox reactions involve both oxidation and reduction halves that always occur together. Tests are described to identify oxidizing agents using potassium iodide solution, which will turn reddish brown if iodine is liberated, indicating an oxidizing agent is present.
An oxidation-reduction (redox) reaction is a type of chemical reaction that involves a transfer of electrons between two species. An oxidation-reduction reaction is any chemical reaction in which the oxidation number of a molecule, atom, or ion changes by gaining or losing an electron.
Includes a discussion of Voltaic and electrolytic cells, the Nernst equation and the relationship between electrochemical processes, chemical equilibrium and free energy.
**More good stuff available at:
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I hope You all like it. I hope It is very beneficial for you all. I really thought that you all get enough knowledge from this presentation. This presentation is about materials and their classifications. After you read this presentation you knowledge is not as before.
An oxidation-reduction (redox) reaction is a type of chemical reaction that involves a transfer of electrons between two species. An oxidation-reduction reaction is any chemical reaction in which the oxidation number of a molecule, atom, or ion changes by gaining or losing an electron.
Includes a discussion of Voltaic and electrolytic cells, the Nernst equation and the relationship between electrochemical processes, chemical equilibrium and free energy.
**More good stuff available at:
www.wsautter.com
and
http://www.youtube.com/results?search_query=wnsautter&aq=f
I hope You all like it. I hope It is very beneficial for you all. I really thought that you all get enough knowledge from this presentation. This presentation is about materials and their classifications. After you read this presentation you knowledge is not as before.
Concept of oxidation and reduction, redox reactions, oxidation number, balancing redox reactions, loss and gain of electrons, Balancing redox reactions, Half reaction method, Types of redox reaction- direct and indirect method, Electrochemical cell, Classification of redox reactions.
this is a ppt made bby Hima Mohammed
well, made this when I was in 7th grade.
subject : chemistry
hope you ll like it
enjoy..
good luck
let me know wat d u think about this powerpoint presntation
Discusses the chemical of slightly soluble compounds. Ksp and factors affecting solubility are included as well as solved problems.
**More good stuff available at:
www.wsautter.com
and
http://www.youtube.com/results?search_query=wnsautter&aq=f
Concept of oxidation and reduction, redox reactions, oxidation number, balancing redox reactions, loss and gain of electrons, Balancing redox reactions, Half reaction method, Types of redox reaction- direct and indirect method, Electrochemical cell, Classification of redox reactions.
this is a ppt made bby Hima Mohammed
well, made this when I was in 7th grade.
subject : chemistry
hope you ll like it
enjoy..
good luck
let me know wat d u think about this powerpoint presntation
Discusses the chemical of slightly soluble compounds. Ksp and factors affecting solubility are included as well as solved problems.
**More good stuff available at:
www.wsautter.com
and
http://www.youtube.com/results?search_query=wnsautter&aq=f
contains explanation of redox reaction, differences between oxidation and reduction, related pictures and solved examples along with test your understanding section.
This the reaction that explains the loose or gain oxygen, hydrogen, electron transfer and the increase or decrease of oxidation number.
In this slide, we also talk about the oxidation number: how it is being calculated, examples of element in a compound with their oxidation number
Introduction to redox reactions
References
Tindale, Ritchie et al, 2014, Chemistry for CSEC 2nd Edition, Nelson Thornes. p156-159
Electron Transfer in Redox Reactions Todayhttps://www.sewanhakaschools.org
(May 29th, 2024) Advancements in Intravital Microscopy- Insights for Preclini...Scintica Instrumentation
Intravital microscopy (IVM) is a powerful tool utilized to study cellular behavior over time and space in vivo. Much of our understanding of cell biology has been accomplished using various in vitro and ex vivo methods; however, these studies do not necessarily reflect the natural dynamics of biological processes. Unlike traditional cell culture or fixed tissue imaging, IVM allows for the ultra-fast high-resolution imaging of cellular processes over time and space and were studied in its natural environment. Real-time visualization of biological processes in the context of an intact organism helps maintain physiological relevance and provide insights into the progression of disease, response to treatments or developmental processes.
In this webinar we give an overview of advanced applications of the IVM system in preclinical research. IVIM technology is a provider of all-in-one intravital microscopy systems and solutions optimized for in vivo imaging of live animal models at sub-micron resolution. The system’s unique features and user-friendly software enables researchers to probe fast dynamic biological processes such as immune cell tracking, cell-cell interaction as well as vascularization and tumor metastasis with exceptional detail. This webinar will also give an overview of IVM being utilized in drug development, offering a view into the intricate interaction between drugs/nanoparticles and tissues in vivo and allows for the evaluation of therapeutic intervention in a variety of tissues and organs. This interdisciplinary collaboration continues to drive the advancements of novel therapeutic strategies.
Introduction:
RNA interference (RNAi) or Post-Transcriptional Gene Silencing (PTGS) is an important biological process for modulating eukaryotic gene expression.
It is highly conserved process of posttranscriptional gene silencing by which double stranded RNA (dsRNA) causes sequence-specific degradation of mRNA sequences.
dsRNA-induced gene silencing (RNAi) is reported in a wide range of eukaryotes ranging from worms, insects, mammals and plants.
This process mediates resistance to both endogenous parasitic and exogenous pathogenic nucleic acids, and regulates the expression of protein-coding genes.
What are small ncRNAs?
micro RNA (miRNA)
short interfering RNA (siRNA)
Properties of small non-coding RNA:
Involved in silencing mRNA transcripts.
Called “small” because they are usually only about 21-24 nucleotides long.
Synthesized by first cutting up longer precursor sequences (like the 61nt one that Lee discovered).
Silence an mRNA by base pairing with some sequence on the mRNA.
Discovery of siRNA?
The first small RNA:
In 1993 Rosalind Lee (Victor Ambros lab) was studying a non- coding gene in C. elegans, lin-4, that was involved in silencing of another gene, lin-14, at the appropriate time in the
development of the worm C. elegans.
Two small transcripts of lin-4 (22nt and 61nt) were found to be complementary to a sequence in the 3' UTR of lin-14.
Because lin-4 encoded no protein, she deduced that it must be these transcripts that are causing the silencing by RNA-RNA interactions.
Types of RNAi ( non coding RNA)
MiRNA
Length (23-25 nt)
Trans acting
Binds with target MRNA in mismatch
Translation inhibition
Si RNA
Length 21 nt.
Cis acting
Bind with target Mrna in perfect complementary sequence
Piwi-RNA
Length ; 25 to 36 nt.
Expressed in Germ Cells
Regulates trnasposomes activity
MECHANISM OF RNAI:
First the double-stranded RNA teams up with a protein complex named Dicer, which cuts the long RNA into short pieces.
Then another protein complex called RISC (RNA-induced silencing complex) discards one of the two RNA strands.
The RISC-docked, single-stranded RNA then pairs with the homologous mRNA and destroys it.
THE RISC COMPLEX:
RISC is large(>500kD) RNA multi- protein Binding complex which triggers MRNA degradation in response to MRNA
Unwinding of double stranded Si RNA by ATP independent Helicase
Active component of RISC is Ago proteins( ENDONUCLEASE) which cleave target MRNA.
DICER: endonuclease (RNase Family III)
Argonaute: Central Component of the RNA-Induced Silencing Complex (RISC)
One strand of the dsRNA produced by Dicer is retained in the RISC complex in association with Argonaute
ARGONAUTE PROTEIN :
1.PAZ(PIWI/Argonaute/ Zwille)- Recognition of target MRNA
2.PIWI (p-element induced wimpy Testis)- breaks Phosphodiester bond of mRNA.)RNAse H activity.
MiRNA:
The Double-stranded RNAs are naturally produced in eukaryotic cells during development, and they have a key role in regulating gene expression .
Professional air quality monitoring systems provide immediate, on-site data for analysis, compliance, and decision-making.
Monitor common gases, weather parameters, particulates.
THE IMPORTANCE OF MARTIAN ATMOSPHERE SAMPLE RETURN.Sérgio Sacani
The return of a sample of near-surface atmosphere from Mars would facilitate answers to several first-order science questions surrounding the formation and evolution of the planet. One of the important aspects of terrestrial planet formation in general is the role that primary atmospheres played in influencing the chemistry and structure of the planets and their antecedents. Studies of the martian atmosphere can be used to investigate the role of a primary atmosphere in its history. Atmosphere samples would also inform our understanding of the near-surface chemistry of the planet, and ultimately the prospects for life. High-precision isotopic analyses of constituent gases are needed to address these questions, requiring that the analyses are made on returned samples rather than in situ.
Slide 1: Title Slide
Extrachromosomal Inheritance
Slide 2: Introduction to Extrachromosomal Inheritance
Definition: Extrachromosomal inheritance refers to the transmission of genetic material that is not found within the nucleus.
Key Components: Involves genes located in mitochondria, chloroplasts, and plasmids.
Slide 3: Mitochondrial Inheritance
Mitochondria: Organelles responsible for energy production.
Mitochondrial DNA (mtDNA): Circular DNA molecule found in mitochondria.
Inheritance Pattern: Maternally inherited, meaning it is passed from mothers to all their offspring.
Diseases: Examples include Leber’s hereditary optic neuropathy (LHON) and mitochondrial myopathy.
Slide 4: Chloroplast Inheritance
Chloroplasts: Organelles responsible for photosynthesis in plants.
Chloroplast DNA (cpDNA): Circular DNA molecule found in chloroplasts.
Inheritance Pattern: Often maternally inherited in most plants, but can vary in some species.
Examples: Variegation in plants, where leaf color patterns are determined by chloroplast DNA.
Slide 5: Plasmid Inheritance
Plasmids: Small, circular DNA molecules found in bacteria and some eukaryotes.
Features: Can carry antibiotic resistance genes and can be transferred between cells through processes like conjugation.
Significance: Important in biotechnology for gene cloning and genetic engineering.
Slide 6: Mechanisms of Extrachromosomal Inheritance
Non-Mendelian Patterns: Do not follow Mendel’s laws of inheritance.
Cytoplasmic Segregation: During cell division, organelles like mitochondria and chloroplasts are randomly distributed to daughter cells.
Heteroplasmy: Presence of more than one type of organellar genome within a cell, leading to variation in expression.
Slide 7: Examples of Extrachromosomal Inheritance
Four O’clock Plant (Mirabilis jalapa): Shows variegated leaves due to different cpDNA in leaf cells.
Petite Mutants in Yeast: Result from mutations in mitochondrial DNA affecting respiration.
Slide 8: Importance of Extrachromosomal Inheritance
Evolution: Provides insight into the evolution of eukaryotic cells.
Medicine: Understanding mitochondrial inheritance helps in diagnosing and treating mitochondrial diseases.
Agriculture: Chloroplast inheritance can be used in plant breeding and genetic modification.
Slide 9: Recent Research and Advances
Gene Editing: Techniques like CRISPR-Cas9 are being used to edit mitochondrial and chloroplast DNA.
Therapies: Development of mitochondrial replacement therapy (MRT) for preventing mitochondrial diseases.
Slide 10: Conclusion
Summary: Extrachromosomal inheritance involves the transmission of genetic material outside the nucleus and plays a crucial role in genetics, medicine, and biotechnology.
Future Directions: Continued research and technological advancements hold promise for new treatments and applications.
Slide 11: Questions and Discussion
Invite Audience: Open the floor for any questions or further discussion on the topic.
This pdf is about the Schizophrenia.
For more details visit on YouTube; @SELF-EXPLANATORY;
https://www.youtube.com/channel/UCAiarMZDNhe1A3Rnpr_WkzA/videos
Thanks...!
Earliest Galaxies in the JADES Origins Field: Luminosity Function and Cosmic ...Sérgio Sacani
We characterize the earliest galaxy population in the JADES Origins Field (JOF), the deepest
imaging field observed with JWST. We make use of the ancillary Hubble optical images (5 filters
spanning 0.4−0.9µm) and novel JWST images with 14 filters spanning 0.8−5µm, including 7 mediumband filters, and reaching total exposure times of up to 46 hours per filter. We combine all our data
at > 2.3µm to construct an ultradeep image, reaching as deep as ≈ 31.4 AB mag in the stack and
30.3-31.0 AB mag (5σ, r = 0.1” circular aperture) in individual filters. We measure photometric
redshifts and use robust selection criteria to identify a sample of eight galaxy candidates at redshifts
z = 11.5 − 15. These objects show compact half-light radii of R1/2 ∼ 50 − 200pc, stellar masses of
M⋆ ∼ 107−108M⊙, and star-formation rates of SFR ∼ 0.1−1 M⊙ yr−1
. Our search finds no candidates
at 15 < z < 20, placing upper limits at these redshifts. We develop a forward modeling approach to
infer the properties of the evolving luminosity function without binning in redshift or luminosity that
marginalizes over the photometric redshift uncertainty of our candidate galaxies and incorporates the
impact of non-detections. We find a z = 12 luminosity function in good agreement with prior results,
and that the luminosity function normalization and UV luminosity density decline by a factor of ∼ 2.5
from z = 12 to z = 14. We discuss the possible implications of our results in the context of theoretical
models for evolution of the dark matter halo mass function.
A brief information about the SCOP protein database used in bioinformatics.
The Structural Classification of Proteins (SCOP) database is a comprehensive and authoritative resource for the structural and evolutionary relationships of proteins. It provides a detailed and curated classification of protein structures, grouping them into families, superfamilies, and folds based on their structural and sequence similarities.
Multi-source connectivity as the driver of solar wind variability in the heli...Sérgio Sacani
The ambient solar wind that flls the heliosphere originates from multiple
sources in the solar corona and is highly structured. It is often described
as high-speed, relatively homogeneous, plasma streams from coronal
holes and slow-speed, highly variable, streams whose source regions are
under debate. A key goal of ESA/NASA’s Solar Orbiter mission is to identify
solar wind sources and understand what drives the complexity seen in the
heliosphere. By combining magnetic feld modelling and spectroscopic
techniques with high-resolution observations and measurements, we show
that the solar wind variability detected in situ by Solar Orbiter in March
2022 is driven by spatio-temporal changes in the magnetic connectivity to
multiple sources in the solar atmosphere. The magnetic feld footpoints
connected to the spacecraft moved from the boundaries of a coronal hole
to one active region (12961) and then across to another region (12957). This
is refected in the in situ measurements, which show the transition from fast
to highly Alfvénic then to slow solar wind that is disrupted by the arrival of
a coronal mass ejection. Our results describe solar wind variability at 0.5 au
but are applicable to near-Earth observatories.
1. Define oxidation and reduction
Define the oxidation number from formulae
Describe tests for oxidising and reducing agents
Distinguish between oxidising and reducing agents
Chapter 11
Redox Reactions
LEARNING OUTCOMES
2. For example, when magnesium is burned in oxygen, it
changes into magnesium oxide. We say that the
magnesium is oxidised into magnesium oxide.
Oxidation can be defined as the gain of oxygen by a substance.
The magnesium has gained oxygen to
become magnesium oxide.
2Mg(s) + O2(g) 2MgO(s)
Oxygen added
Magnesium + Oxygen Magnesium oxide
Oxidation as the gain of oxygen
Chapter 11
Redox Reactions
3. For example, when copper(II) oxide is heated with
hydrogen, it changes to copper. We say that the
copper(II) oxide has been reduced to copper.
Reduction can be defined as the loss or removal of
oxygen from a substance.
Reduction as the loss of oxygen
Chapter 11
Redox Reactions
4. Oxygen removed
The copper(II) oxide has changed into
copper by its loss of oxygen.
CuO(s) + H2(g) Cu(s) + H2O(l)
Copper(II) oxide + Hydrogen Copper + water
Reduction as the loss of oxygen
Chapter 11
Redox Reactions
5. Hydrogen removed
Oxidation may also be defined as the loss or removal of
hydrogen from a substance.
H2S(g) + Cl2(g) S(s) + 2HCl(g)
We say that the hydrogen sulphide is oxidised
to sulphur, because it has lost hydrogen.
For example, hydrogen sulphide reacts with
chlorine to form sulphur and hydrogen chloride:
Oxidation as the loss of hydrogen
Chapter 11
Redox Reactions
6. Conversely, reduction may be defined as the gain or addition
of hydrogen to a substance.
N2(g) + 3H2(g) 2NH3(g)
Hydrogen added
In this reaction, nitrogen is reduced to
ammonia, because it has gained hydrogen.
For example, nitrogen reacts with hydrogen to
form ammonia in the Haber process:
Reduction as the gain of hydrogen
Chapter 11
Redox Reactions
7. Oxygen
added
In a redox reaction, if one substance is oxidised, the other is
being reduced.
E.g. The extraction of iron from iron(III) oxide in the blast
furnace:
Fe2O3(s) + 3CO(g) 2Fe(l) + 3CO2(g)
Fe2O3 loses oxygen,
and is thus reduced.
CO gains oxygen,
and is thus oxidised.
We say that iron(III) oxide is reduced to iron, and carbon
monoxide is oxidised to carbon dioxide.
Redox Reactions always occur together
Chapter 11
Redox Reactions
8. Hydrogen
added
For example, in the reaction of hydrogen sulphide with
chlorine:
H2S loses hydrogen,
and is thus oxidised.
Cl2 gains hydrogen,
and is thus reduced.
We say that hydrogen sulphide is oxidised to sulphur, and
chlorine is reduced to hydrogen chloride.
H2S(g) + Cl2(g) S(s) + 2HCl(g)
Redox reactions always occur together
Chapter 11
Redox Reactions
10. Quick check 1
1. State which substance is oxidised. What substance has it
oxidised to? Give a reason for your answer.
(a) C + O2 CO2
(b) Mg + H2O MgO + H2
(c) 2CO + O2 2CO2
(d) H2I + Cl2 2HCl + I2
(e) CuO + H2 Cu + H2O
(f) Cl2(g) + H2S(g) 2HCl(g) + S(s)
(g) 2NH3 + 3CuO 3Cu + N2 + 3H2O Solution
Chapter 11
Redox Reactions
11. Quick check 1 (cont’d)
2. State which substance is reduced. What substance has it been
reduced to? Give a reason for your answer.
(a) ZnO + H2 Zn + H2O
(b) CO2 + 2Mg 2MgO + C
(c) Mg + H2O MgO + H2
(d) Fe2O3 + 3CO 2Fe + 3CO2
(e) H2 + Cl2 2HCl
(f) CuO + Mg Cu + MgO
(g) FeS + 2HCl FeCl2 + H2S
Solution
Chapter 11
Redox Reactions
12. We define:
Oxidation is the loss of electrons from an
atom or ion.
Reduction is the gain of electrons by an atom or ion.
Redox reactions can take place even if
no oxygen or hydrogen is involved.
A redox reaction is deemed to occur if there is
a transfer of electron(s) during the reaction.
Redox reactions in terms of electron transfer
Chapter 11
Redox Reactions
13. For example, when sodium and chlorine react to form sodium
chloride:
The sodium atom has transferred its outermost electron
to chlorine to form sodium chloride.
The sodium atom has lost an electron, hence it is oxidised.
The chlorine atom has gained an electron, hence it is reduced.
Chapter 11
Redox Reactions
Redox reactions in terms of electron transfer
14. 2Na + Cl2 2Na+
+ 2Cl-
Na loses electrons (oxidation)
Cl2 gains electrons (reduction)
We say that sodium is oxidised (loss of electron) and chlorine is
reduced (gain of electron) to form sodium chloride.
Example 1: Reaction of sodium with chlorine
Chapter 11
Redox Reactions
Redox reactions in terms of electron transfer
15. Example 2: Reaction of magnesium with hydrochloric acid
Mg + 2H+
Cl-
Mg2+
Cl-
2 + H2
H+
gains electrons (reduction)
We say that magnesium is oxidised to
magnesium chloride. (loss of electrons)
We say that hydrochloric acid is
reduced to hydrogen. (gain of electron).
Mg loses electrons (oxidation)
Chapter 11
Redox Reactions
Redox Reactions In Terms of Electron Transfer
16. 2Fe2+
Cl-
2 + Cl2 2Fe3+
Cl-
3
Example 3: Reaction of iron(II) chloride with chlorine.
Fe2+
loses electron to become Fe3+
(Oxidation)
Cl gains electron to become Cl-
(Reduction)
Iron(II) chloride is oxidised to iron(III) chloride (loss of electrons)
Chlorine is reduced to iron(III) chloride (gain of electrons)
Chapter 11
Redox Reactions
Redox reactions in terms of electron transfer
17. To determine if an atom or ion has gained or lost electrons, we can
look at its oxidation state (or oxidation number).
All free (uncombined) elements are assigned an oxidation state of
zero:
E.g. Na0
, Mg0
, Fe0
, Cu0
, H2
0
, Cl2
0
, O2
0
The oxidation state of an element in a compound is equal to the
charge on the ion:
E.g. H+
, Na+
, K+
(oxidation state +1);
Cl-
, Br-
, I-
(oxidation state -1);
Mg2+
, Ca2+
, Zn2+
, Fe2+
(oxidation state +2);
O2-
, S2-
, (oxidation state -2);
Fe3+
, Al3+
(oxidation state +3)
Oxidation States
Chapter 11
Redox Reactions
18. When an atom or ion loses an electron, it is oxidised and its
oxidation state increases:
E.g. Na0
Na+
+ e-
(From 0 +1)
E.g. Fe2+
Fe3+
+ e-
(From +2 +3)
When an atom or ion gains an electron, it is reduced and its
oxidation state decreases:
E.g. Cl0
+ e-
Cl-
(From 0 -1)
E.g. Mg2+
+ 2e-
Mg (From +2 0)
Redox reactions as changes in
oxidation state
Chapter 11
Redox Reactions
19. Example 1: Reaction of magnesium with hydrochloric acid
Step 1: Write down the balanced chemical equation.
Step 2: Write down the oxidation number of each
atom or ion in the equation.
Mg + 2H Cl Mg Cl2 + H2
0 + - 2+ - 0
Redox reactions as changes in
oxidation state
Chapter 11
Redox Reactions
20. Step 3: Look for an atom or ion which has changed its oxidation
number in going from left to right in the equation.
Mg + 2H Cl Mg Cl2 + H2
0 + - 2+ - 0
Step 4: Determine whether it is oxidation (increase in
oxidation state) or reduction (decrease in
oxidation state).
Oxidation (from 0 to +2)
Reduction (from + 1 to 0)
Redox reactions as changes in
oxidation state
Chapter 11
Redox Reactions
21. 2K+
I−
+ Cl2
0
2K+
Cl−
+ I2
0
Potassium iodide isPotassium iodide is oxidisedoxidised to iodine.to iodine.
(( increaseincrease in oxidation state)in oxidation state)
Chlorine isChlorine is reducedreduced to KClto KCl
(( decreasedecrease in oxidation state)in oxidation state)
Example 2: Reaction of potassium iodide with chlorine.
Notice that there is no change in K+
(in KI) to K+
(in KCl);
hence the potassium ion has not been oxidised or reduced.
Redox reactions as changes in
oxidation state
Chapter 11
Redox Reactions
22. KMnO4
KK++
(+1)(+1) xx
4(O4(O2-2-
))
(-2)(-2)
Atoms in covalent and complex compounds can be given
oxidation states, assuming they are ionic.
Oxidation states of all atoms in a compound must add up to zero
Example: Find the oxidation state of Mn in KMnO4.
+1 + x + 4(-2) = 0
x = +7
Determination of Oxidation States
in a Compound
Chapter 11
Redox Reactions
23. Oxidation Reduction
Gain of oxygen Loss of oxygen
Loss of hydrogen Gain of hydrogen
Loss of electron(s)
(Increase in oxidation state)
Gain of electron(s)
(Decrease in oxidation state)
Summary
Chapter 11
Redox Reactions
24. 1. State which substance is oxidised. What substance has it been
oxidised to? State a reason for your answer.
(a) Zn + 2HCl ZnCl2 + H2
(b) Mg + H2SO4 MgSO4 + H2
(c) Fe + Cl2 FeCl2
(d) Zn + CuSO4 ZnSO4 + Cu
(e) Fe + Pb(NO3)2 Fe(NO3)2 + Pb
(f) 2KI + Br2 2KBr + I2
Solution
Quick check 2
Chapter 11
Redox Reactions
25. 2. State which substance is reduced. What substance has it
been reduced to? State a reason for your answer.
(a) CuO + Mg MgO + Cu
(b) 2Fe3+
+ 2Cl-
2Fe2+
+ Cl2
(c) 2Na + Cl2 2NaCl
(d) Zn + CuSO4 ZnSO4 + Cu
(e) Mg + H2SO4 MgSO4 + H2
3. State the oxidation state of nitrogen in the following:
(i) NO, (ii) N2O, (iii) NO2, (iv) NO3
-
Solution
Quick check 2 (cont’d)
Chapter 11
Redox Reactions
26. 2Mg(s) + O2(g) 2MgO(s)
In the above reaction, magnesium is
oxidised into magnesium oxide by oxygen.
Consider the burning of magnesium in
oxygen to form magnesium oxide:
Oxygen is called the oxidising agent.
Oxidising Agents and Reducing Agents
Chapter 11
Redox Reactions
27. An oxidising agent is a substance which causes
oxidation. It acts as an acceptor of electrons.
2Mg(s) + O2(g) 2MgO(s)
In the above reaction, oxygen has received or
accepted 2 electrons from magnesium to
form magnesium oxide.
Hence oxygen is the oxidising agent.Hence oxygen is the oxidising agent.
Definition:
Oxidising Agents
Chapter 11
Redox Reactions
28. Other examples of oxidising agents are:
chlorine and bromine
potassium manganate(VII)
potassium dichromate(VI)
Oxidising Agents
Chapter 11
Redox Reactions
29. Consider the reaction between heated
copper(II) oxide and hydrogen.
CuO(s) + H2(g) Cu(s) + H2O(g)
Copper(II) oxide is reduced to copper by
hydrogen.
Hydrogen is called the reducing agentreducing agent..
Reducing Agents
Chapter 11
Redox Reactions
30. A reducing agent is a substance which causes
reduction. It acts as a donor of electrons.
CuO(s) + H2(g) Cu(s) + H2O(g)
In the above reaction, hydrogen has given
away (donated) 2 electrons to the
copper(II) ion which then becomes copper.
Hence hydrogen is the reducing agent.Hence hydrogen is the reducing agent.
Definition:
Reducing Agents
Chapter 11
Redox Reactions
31. Other examples of reducing agents are:
carbon
carbon monoxide
reactive metals like potassium, sodium, magnesium and aluminium
potassium iodide
Reducing Agents
Chapter 11
Redox Reactions
32. Since redox reactions always occur together, an oxidising agent will
be the substance reduced in the reaction.
Similarly, a reducing agent will be the substance oxidised in the
reaction.
H2S(g) + Cl2(g) S(s) + 2HCl(g)
HH22S is oxidised toS is oxidised to
sulphur bysulphur by chlorine.chlorine.
Chlorine is reduced to HClChlorine is reduced to HCl
byby hydrogen sulphide.hydrogen sulphide.
HH22S is the reducing agent.S is the reducing agent.ClCl22 is the oxidising agent.is the oxidising agent.
Oxidising Agents and Reducing Agents
Chapter 11
Redox Reactions
33. (a) Which substance is oxidised?
Ans: ________________________________________
(b) Which substance is reduced?
Ans: ________________________________________
(c) Which is the oxidising agent?
Ans: ________________________________________
(d) Which is the reducing agent?
Ans: ________________________________________
Worked Example
Fe2O3(s) + 3CO(g) 2Fe(l) + 3CO2(g)
Carbon monoxide is oxidised (gain of oxygen)
Iron(III) oxide is reduced (loss of oxygen)
Iron(III) oxide is the oxidising agent.
Carbon monoxide is the reducing agent.
Consider the
following reaction:
Chapter 11
Redox Reactions
34. Test for oxidising agent
To test if an unknown substance is an oxidising agent, add a
solution of potassium iodide to it.
If the mixture turns reddish brown due to the liberation of iodine
from the potassium iodide, then the unknown substance is an
oxidising agent.
Potassium iodide
solution added
unknown
solution
Mixture turns
reddish brown
Chapter 11
Redox Reactions
35. To test if an unknown substance is a reducing agent, add an
acidified solution of potassium dichromate(VI)solution of potassium dichromate(VI) to it.
If the mixture turns from yellow/orange to green,green, then the
unknown substance is a reducing agentreducing agent.
Test for reducing agent
Chapter 11
Redox Reactions
36. 1. In each of the following reactions, state
(i) the substance oxidised, (ii) the substance reduced, (iii) the
oxidising agent and (iv) the reducing agent.
(a) ZnO + CO Zn + CO2
(b) Al2O3 + 3Mg 2Al + 3MgO
(c) 2FeCl2 + Cl2 2FeCl3
2. (a) Define oxidation in terms of electron transfer.
(b) Give an example of a redox reaction, including a
chemical equation with state symbols.
State clearly in your example, which substance is
oxidised and which substance is reduced.
Solution
Quick check 3
Chapter 11
Redox Reactions
37. Solution to Quick check 1
1. (a) C + O2 CO2
Carbon is oxidised into carbon dioxide. (gain of oxygen)
(b) Mg + H2O MgO + H2
Magnesium is oxidised into magnesium oxide. (gain of oxygen)
(c) 2CO + O2 2CO2
Carbon monoxide is oxidised into carbon dioxide. (gain of oxygen)
(d) H2I + Cl2 2HCl + I2
Hydrogen iodide is oxidised into iodine. (loss of hydrogen)
(e) CuO + H2 Cu + H2O
Hydrogen is oxidised into water. (gain of oxygen)
(f) Cl2(g) + H2S(g) 2HCl(g) + S(s)
Hydrogen sulphide is oxidised into sulphur. (loss of hydrogen)
(g) 2NH3 + 3CuO 3Cu + N2 + 3H2O
Ammonia is oxidised into nitrogen. (loss of hydrogen)
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Chapter 11
Redox Reactions
38. 2.
(a) ZnO + H2 Zn + H2O
Zinc oxide is reduced into zinc. (loss of oxygen)
(b) CO2 + 2Mg 2MgO + C
Carbon dioxide is reduced into carbon. (loss of oxygen)
(c) Mg + H2O MgO + H2
Water is reduced into hydrogen. (loss of oxygen)
(d) Fe2O3 + 3CO 2Fe + 3CO2
Iron(III) oxide is reduced into iron. (loss of oxygen)
(e) H2 + Cl2 2HCl
Chlorine is reduced into hydrogen chloride. (gain of hydrogen)
(f) CuO + Mg Cu + MgO
Copper(II) oxide is reduced into copper.(loss of oxygen)
(g) FeS + 2HCl FeCl2 + H2S
Iron(II) sulphide is reduced to hydrogen sulphide. (gain of hydrogen)
Return
Solution to Quick check 1 (cont’d)
Chapter 11
Redox Reactions
39. 1. (a) Zn + 2HCl ZnCl2 + H2
Zinc is oxidised into zinc chloride.
(loss of electrons/increase in oxidation state)
(b) Mg + H2SO4 MgSO4 + H2
Magnesium is oxidised to magnesium sulphate.
(loss of electrons)
(c) Fe + Cl2 FeCl2
Iron is oxidised to iron(II) chloride. (loss of electrons)
(d) Zn + CuSO4 ZnSO4 + Cu
Zinc is oxidised to zinc sulphate. (loss of electrons)
(e) Fe + Pb(NO3)2 Fe(NO3)2 + Pb
Iron is oxidised to iron(II) nitrate. (loss of electrons)
(f) 2KI + Br2 2KBr + I2
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Solution to Quick check 2
Chapter 11
Redox Reactions
40. 2. (a) CuO + Mg MgO + Cu
Copper(II) oxide is reduced to copper.
(loss of oxygen/decrease in oxidation state/gain of electrons)
(b) 2Fe3+
+ 2Cl-
2Fe2+
+ Cl2
Iron(III) is reduced to iron(II). Decrease in oxidation state/gain of electron.
(c) 2Na + Cl2 2NaCl
Chlorine is reduced to sodium chloride. (gain of electron)
(d) Zn + CuSO4 ZnSO4 + Cu
Copper(II) sulphate is reduced to copper (gain of electrons)
(e) Mg + H2SO4 MgSO4 + H2
Sulphuric acid is reduced to hydrogen (gain of electron)
3. (i) +2, (ii) +1, (iii) +4, (iv) +5 Return
Solution to Quick check 2 (cont’d)
Chapter 11
Redox Reactions
41. 1. (a) ZnO + CO Zn + CO2
(i) carbon monoxide, (ii) zinc oxide,
(iii) zinc oxide, (iv) carbon monoxide
(b) Al2O3 + 3Mg 2Al + 3MgO
(i) magnesium, (ii) aluminium oxide,
(iii) aluminium oxide, (iv) magnesium
(c) 2FeCl2 + Cl2 2FeCl3
(i) iron(II) chloride, (ii) chlorine,
(iii) chlorine, (iv) iron(II) chloride
2. (a) Oxidation occurs when there is a loss of electrons from an atom or
ion.
(b) 2KI(aq) + Cl2 (g) 2KCl(aq) + I2(s)
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Solution to Quick check 3
Chapter 11
Redox Reactions