Chapter 5 – Analysing Oxidants & Reductants Week 3, Lesson 1.

Slides:



Advertisements
Similar presentations
Oxidation and Reduction (Redox) Lance S. Lund April 19, 2011.
Advertisements

Oxidation and Reduction Chem 1061 – Tro, Chapter 4 Lance S. Lund.
Redox Reactions Chapter 18 + O2 .
Chapter 4B: Balancing Redox Reactions
Oxidation Number Rules  The oxidation number of any free, uncombined element is zero. n The oxidation number of an element in a simple (monatomic) ion.
Redox Reactions Chapter 18 + O 2 . Oxidation-Reduction (Redox) Reactions “redox” reactions: rxns in which electrons are transferred from one species.
Volumetric Analysis. Volumetric analysis involves the analysis of a solution of unknown concentration with a standard solution. A pipette is used to transfer.
Balancing Redox Equations: following the electrons Review: Oxidation and reduction Oxidation numbers.
Copyright Sautter REVIEW OF ELECTROCHEMISTRY All electrochemical reactions involve oxidation and reduction. Oxidation means the loss of electrons.
Advanced Higher Chemistry Unit 1 Oxidation states of the transition metals.
Redox Reactions. What is redox? Redox reactions involve a transfer of electrons. Oxidation – involves losing electrons (increase in oxidation number)
 Oxidation is a chemical change in which electrons are lost by an atom or group of atoms.  Zn(s)  Zn 2+ (aq) + 2 e - (oxidized0  Example: The reaction.
Chapter 20 – Redox Reactions One of the earliest recognized chemical reactions were with oxygen. Some substances would combine with oxygen, and some would.
Oxidation Reduction Reactions. Oxidation Reduction Reactions… are chemical changes that occur when electrons are transferred between reactants.
REDOX Reactions Oxidation – Reduction.
CHAPTER 4 AP CHEMISTRY. PRECIPITATION PROBLEMS Water Highly polar Ionic and polar compounds are attracted to the positive and/or negative ends of the.
Unit 5 ELECTROCHEMISTRY.
REDOX Oxidation and Reduction Chapters 20 and 21.
REDOX REVIEW Assigning Oxidation Numbers Balancing Half Reactions.
Oxidation Numbers & Redox Reactions How to Make Balancing Redox Reactions a Relatively Painless Process.
CHAPTER 4 Aqueous Reactions and Solution Stoichiometry 1.
Redox Reactions Year 11 Chemistry ~ Unit 2.
Redox Reactions.
CHAPTER 5 ANALYSING OXIDANTS AND REDUCTANTS. REDOX REACTIONS Redox reactions involve complementary processes of oxidation and reduction, and can be identified.
1 Oxidation- Reduction Chapter 16 Tro, 2 nd ed. 1.1.
REDOX AND ELECTROCHEMISTRY Oxidation Number A. Convenient way for keeping track of the number of electrons transferred in a chemical reaction A. Convenient.
Objective: Determine the equivalence point. Equivalence point n OH - = n H + If 25.00mL of M NaOH is needed to react with mL of HCl. What is.
TEKS 10H: Understand and differentiate among acid-base reactions, precipitation reactions, and oxidation-reduction reactions. What are oxidation numbers?
Oxidation Number. What is an Oxidation Number? Oxidation-reduction reactions (redox reactions) are reactions in which electrons are lost by an atom or.
Oxidation/Reduction Reactions REDOX REACTONS! All chemical reactions fall into two categories those that are redox and those that are not redox! Redox.
Aqueous Reactions CHAPTER 20 “Oxidation-Reduction Reactions” LEO SAYS GER.
Redox Reactions. Redox is the abbreviated way to write reduction- oxidation reaction. Redox is the abbreviated way to write reduction- oxidation reaction.
Oxidation-Reduction Reactions Redox. Iron is oxidized when it rusts.
Sodium loses an electron - oxidation Chlorine gains an electron - reduction.
Redox Reactions. REDOX-OXIDATION STATES Day One.
Oxidation Numbers and Redox Reactions Section 7.2.
Oxidation, Reduction and Electrochemistry
The Finish Line is in site… Electrochemistry. Oxidation Numbers OBJECTIVES Determine the oxidation number of an atom of any element in a pure substance.
Oxidation States Assigning oxidation numbers 1. Assigning Oxidation Numbers An “oxidation number” is a positive or negative number assigned to an atom.
Oxidation-Reduction Reactions
Electron-transfer reactions are called oxidation-reduction reactions or redox reactions. Oxidation – loss of electrons by one reactant. Reduction – gain.
Calculating and using oxidation numbers. 1 The oxidation number of any free, uncombined element is zero. This includes polyatomic molecules of elements.
Oxidation-Reduction Reactions “Redox” LEO SAYS GER.
CHAPTER 20 “Oxidation-Reduction Reactions” LEO SAYS GER Pre-AP Chemistry Charles Page High School Modified Stephen L. Cotton.
Chemistry Chapter 19 Oxidation and Reduction 1. Oxidation-Reduction Involves movement of electrons Oxidation: ▫Effective loss of electrons Reduction:
Oxidation – Reduction Mr. Chan Northwestern University To insert your company logo on this slid From the Insert Menu Select “Picture” Locate your logo.
Aim: How do chemists assign oxidation numbers? An oxidation-reduction (redox) reaction involves the transfer of electrons (e-). Reduction is the gain of.
Redox Identifying Ox. States Balancing A.) Assigning Oxidation Numbers 1.) An oxidation number is a positive or negative number assigned to an atom.
The Finish Line is in site…
Redox Reactions.
RULES FOR ASSIGNING OXIDATION NUMBERS (STATES
Oxidation-Reduction Chapter 20.
Redox Reactions AP Chemistry Unit 3.
Oxidation-Reduction Reactions
Redox chemistry September 19th, 2016.
Oxidation and Reduction Reactions
REDOX REACTIONS.
AP Chem This is our last unit!.
Types of Reactions in Solution and their Stoichiometry
Chapter 19.1 oxidation number or oxidation state –
BALANCING REDOX EQUATIONS
Electrochemistry Topic #29
Chapter 5 – Analysing Oxidants & Reductants
Click a hyperlink or folder tab to view the corresponding slides.
POWER POINT PRESENTATION ON OXIDATION NUMBERS
Oxidation-Reduction Reactions (REDOX reactions)
Redox Reactions Reduction Oxidation.
Oxidation-Reduction Reactions
Oxidation Reduction.
AP Chem Today: Intro to last unit We will only touch basics this week.
Presentation transcript:

Chapter 5 – Analysing Oxidants & Reductants Week 3, Lesson 1

Redox Reactions Redox reactions involve the transfer of electrons. Two half equations occur during a redox reaction. One reactant loses electrons – this is oxidation. One reactant gains electrons – this is reduction. These two processes occur simultaneously.

Redox Reactions cont… Substances that cause oxidation are called oxidants, or oxidising agents. While, substances that cause reduction are called reductants, or reducing agents.

Oxidation Numbers To determine whether a reaction is a redox reaction, oxidation numbers are assigned to elements involved in the reaction. These numbers are determined by applying a set of rules that treat molecular substances as if they were composed of ions. Oxidation numbers have no physical meaning. Oxidation numbers are also known as oxidation states.

Oxidation Number Rules Free elements have an oxidation number of 0. In ionic compounds composed of simple ions, the oxidation number is the same as the charge on that ion. Some elements have oxidation numbers that are regarded as fixed, except in a few exceptional circumstances: – Oxygen usually takes -2 in compounds, except in peroxides it is -1. – Hydrogen takes +1 in compounds, except in metal hydrides if is -1. The sum of the oxidation number in a neutral compound is zero. In a polyatomic ion the sum of the oxidation numbers is equal to the charge on that ion. The most electronegative element in a compound has the negative oxidation number.

Variable Oxidation Number In all their compounds, the group I metals only have an oxidation number of +1 and the group II metals only have an oxidation number of +2. The oxidation numbers of transition metals vary depending on the compound. The oxidation numbers of non-metallic elements may also vary from compound to compound.

Changing Oxidation Numbers Once oxidation numbers are assigned to the elements involved in a chemical reaction, we can look for a change in these numbers during a reaction. An increased oxidation number means the element has been oxidised. A decreased oxidation number means the element has been reduced.

Writing Half Equations Half equations that involve atoms or simple ions can be written with little difficulty, as you just need to add electrons to the appropriate side. Half equations involving polyatomic ions is a little more difficult. The process is as follows: 1.Balance all elements except hydrogen and oxygen in the half equation. 2.Balance the oxygen atoms by adding water. 3.Balance the hydrogen atoms by adding H + ions. 4.Balance the charge by adding electrons.

Volumetric Analysis This process can also be used to find the concentration of solutions of substances in a redox reaction. Instead of reacting an acid with a base, a redox titration involves reaction of an oxidant with a reductant. To find the concentration, the same process is followed as in an acid-base reaction.