1 Reduction Oxidation Reactions REDOX Is a chemical reaction in which electrons are transferred Must have both reduction and oxidation happening for the reaction to occur REDUCTION a process in which electrons are gained by an entity OXIDATION a process in which electrons are lost by an entity How can you remember this? LEO the lion says GER LEO = Losing Electrons = Oxidation GER = Gaining Electrons = Reduction Other memory devices: OIL RIG (Oxidation Is Losing electrons, Reduction Is Gaining electrons) REGOLE (Reduction Electron Gain Oxidation Loss of Electron)
2 Reduction Oxidation Reactions REDOX Examples of Redox Reactions: Synthesis, decomposition, combustion, single displacement, cellular respiration, photosynthesis, (NOT double displacement)
3 An Introduction to Redox Imagine that a reaction is a combination of two parts called half-reactions. A half reaction represents what is happening to one reactant, it tells one part of the story. Another half-reaction is required to complete the description of the reaction. Example: When metal is placed into hydrochloric acid solution, gas bubbles form as the zinc slowly disappears. Zn (s) + 2HCl (aq) ZnCl 2(aq) + H 2(g What happens to the zinc? To the HCl (aq)? Look at the half-reactions. Zn (s) Zn 2+ (aq) + 2 e - 2 H + (aq) + 2 e - H 2 (g) Notice that both of these half-reactions are balanced by mass (same number of atoms/ions of each element on both sides) and by charge (same total charge on both sides) A half reaction is a balanced chemical equation that represents either a loss or gain of electrons by a substance
4 An Introduction to Redox Imagine that a reaction is a combination of two parts called half-reactions. A half reaction represents what is happening to one reactant, it tells one part of the story. Another half-reaction is required to complete the description of the reaction. Example: When metal is placed into hydrochloric acid solution, gas bubbles form as the zinc slowly disappears. Zn (s) + 2HCl (aq) ZnCl 2(aq) + H 2(g What happens to the zinc? To the HCl (aq)? Look at the half-reactions. Zn (s) Zn 2+ (aq) + 2 e - OXIDATION - entity loses electrons REDUCTION - entity gains electrons 2 H + (aq) + 2 e - H 2 (g) Where is oxidation occurring?? (LEO) Where is reduction occurring?? (GER)
5 An Introduction to Redox Example: When a piece of copper is placed into a beaker of silver nitrate, the following changes occur. Cu (s) + AgNO 3(aq) Cu(NO 3 ) 2(aq) + Ag (s) Write the balanced half-reaction equations: To show that the number of electrons gained equals the number of electrons lost in two half-equations, it may be necessary to multiply one or both half-reaction equations by a coefficient to balance the electrons. I.e. Ag half reaction must be multiplied by 2 Cu (s) Cu 2+ (aq) + 2 e - 2 [Ag + (aq) + e - Ag (s) ] OXIDATION REDUCTION Where is Oxidation occurring? Where is Reduction occurring?
6 An Introduction to Redox OXIDATION REDUCTION Cu (s) Cu 2+ (aq) + 2 e - 2 [Ag + (aq) + e - Ag (s) ] Now add the half-reactions and cancel the terms that appear on both sides of the equation to obtain the net-ionic equation 2 Ag + (aq) + 2 e - + Cu (s) 2 Ag (s) + Cu 2+ (aq) + 2 e - 2 Ag + (aq)+ Cu (s) 2 Ag (s) + Cu 2+ (aq) Silver ions are reduced to silver metal by reaction with copper metal. Simultaneously, copper metal is oxidized to copper(ii) ions by reaction with silver ions.
7 An Introduction to Redox Silver ions are reduced to silver metal by reaction with copper metal. Simultaneously, copper metal is oxidized to copper(ii) ions by reaction with silver ions.
8 An Introduction to Redox There are two methods for developing net ionic equations: 1) ½ reaction method we just learned OR 2) Using the net-ionic equation method from Chem 20 Cu (s) + 2AgNO 3(aq) Cu(NO 3 ) 2(aq) + 2Ag (s) (dissociate high solubility NON-IONIC and ionic compounds) Cu (s) + 2Ag + (aq) + 2 NO - 3 (aq) Cu 2+ (aq)+ 2NO - 3 (aq) + 2Ag (s) (cancel TOTAL spectator IONIC ions) 2 Ag + (aq)+ Cu (s) 2 Ag (s) + Cu 2+ (aq) (Do NET-IONIC we get the same net ionic reaction?? YES!)
9 Summary Electron Transfer Theory A redox reaction is a chemical reaction in which electrons are transferred between entities The total number of electrons gained in the reduction equals the total number of electrons lost in the oxidation Reduction is a process in which electrons are gained by an entity Oxidation is a process in which electrons are lost by an entity Both reduction and oxidation are represented by balanced halfreaction equations.
10 REDOX Reactions. so far Reduction Historically, the formation of a metal from its ore (or oxide) Oxidation Historically, reactions with oxygen I.e. nickel(ii) oxide is reduced by hydrogen gas to nickel metal I.e. iron reacts with oxygen to produce iron(iii) oxide NiO (s) + H 2(g) Ni (s) + H 2 O (l) Ni +2 Ni o 4 Fe (s) + O 2(g) Fe 2 O 3(s) Fe 0 Fe +3 A gain of electrons occurs (so the entity becomes more negative) Electrons are shown as the reactant in the half-reaction A loss of electrons occurs (so the entity becomes more positive) Electrons are shown as the product in the half-reaction
11 Oxidation States An oxidation state is defined as the apparent net electric charge an atom would have if the electron pairs in a covalent bond belonged entirely to the most electronegative atom. An oxidation number is a positive or negative number corresponding to the oxidation state of the atom in a compound. (These are NOT charges!) Example: In water, which is the most electronegative atom, H or O? Oxygen, so we act as if the oxygen owns both electrons in the electron pair. Each oxygen atom has 8 p + and 8 e -. But if the oxygen atom gets to count the two hydrogen electrons (red dots) in the two shared pairs, as its own, then it has 8 p + but 10 e -, leaving an apparent net charge of -2 Each hydrogen atom has 1 p+, but with no additional electron (since oxygen has already counted it), that leaves hydrogen with an apparent net charge of +1
12 Oxidation States Tip: The sum of the oxidation numbers for a neutral compound = 0 The sum of the oxidation numbers for a polyatomic ion = ion charge ** This method only works if there is only one unknown after referring to the above table
13 Oxidation States Example: What is the oxidation number of carbon in methane CH 4? After referring to Table 1, we assign an oxidation number of +1 to hydrogen So now we have some simple math Since a methane molecule is electrically neutral, then the oxidation number of the one carbon atom and the four hydrogen atoms 4(+1) must equal zero. x + 4(+1) = 0 So the oxidation number of carbon is = -4 How do we write this?
14 Oxidation States Example: What is the oxidation number of manganese in a permanganate ion, MnO 4-? After referring to Table 1, we assign an oxidation number of -2 to oxygen Since a permanganate ion has a charge of 1-, then the oxidation number of the one manganese atom and the four oxygen atoms 4(-2) must equal -1. x + 4(-2) = -1 x + -8 = -1 So the oxidation number of manganese is = -7 Example: What is the oxidation number of sulfur in sodium sulfate? We know the oxidation numbers of both Na and O, and solve algebraically 2(+1) + x + 4(-2) = x + -8 = 0 So the oxidation number of sulfur is +6
15 Redox in Living Organisms The ability of carbon to take on different oxidation states is essential to life on Earth. Photosynthesis involves a series of reduction reactions in which the oxidation number of carbon changes from +4 in carbon dioxide to an average of 0 in sugars such as glucose. The smell of a skunk is caused by a thiol compound (R-SH). To deodorize a pet sprayed by a skunk, you need to convert the smelly thiol to an odourless compound. Hydrogen peroxide in a basic solution acts as an oxidizing agent to change the thiol to a disulfide compound (RS-SR), which is odourless.
16 Determining Oxidation Numbers Summary 1. Assign common oxidation numbers (Table 1 on page 658) 2. The total of the oxidation numbers of atoms in a molecule or ion equals the value of the net electric charge of the molecule or ion. a) The sum of the oxidation numbers for a compound is zero. b) The sum of the oxidation numbers for a polyatomic ion equals the charge of the ion. 3. Any unknown oxidation number is determined algebraically from the sum of the known oxidation numbers and the net charge on the entity.
17 Oxidation Numbers and Redox Although the concept of oxidation states is somewhat arbitrary, because it is based on assigned charges, it is self-consistent and allows predictions of electron transfer. Chemists believe that if the oxidation number of an atom or ion changes during a chemical reaction, then an electron transfer (oxidation-reduction reaction) occurs. Based on oxidation numbers, If the oxidation numbers do not change = no transfer of e - s = not a redox rxn An increase in the oxidation number = oxidation A decrease in the oxidation number = reduction
18 Oxidation Numbers and Redox Example: Identify the oxidation and reduction in the reaction of zinc metal with hydrochloric acid. First write the chemical equation (as it is not provided) Determine all of the oxidation numbers Now look for the oxidation number of an atom/ion that increases as a result of the reaction and label the change as oxidation. There must also be an atom/ion whose oxidation number decreases. Label this change as reduction.
19 Oxidation Numbers and Redox Example: When natural gas burns in a furnace, carbon dioxide and water form. Identify oxidation and reduction in this reaction. First write the chemical equation (as it is not provided) Determine all of the oxidation numbers Now look for the oxidation number of an atom/ion that increases as a result of the reaction and label the change as oxidation. There must also be an atom/ion whose oxidation number decreases. Label this change as reduction.
20 Balancing Redox Equations using Oxidation Numbers 1. Assign oxidation numbers and identify the atoms/ions whose oxidation numbers change 2. Using the change in oxidation numbers, write the number of electrons transferred per atom. 3. Using the chemical formulas, determine the number of electrons transferred per reactant. (Use formula subscripts to do this) 4. Calculate the simplest whole number coefficients for the reactants that will balance the total number of electrons transferred. Balance the reactants and products. 5. Balance the O atoms using H 2 O (l), and then balance the H atoms using H + (aq)
21 Balancing Redox Equations using Oxidation Numbers #1 Example: When hydrogen sulfide is burned in the presence of oxygen, it is converted to sulfur dioxide and water vapour. Use oxidation numbers to balance this equation. H 2 S (g) + O 2(g) SO 2(g) + H 2 O (g) 1.Assign oxidation numbers to all atoms/ions and look for the numbers that change. Highlight these. Notice that a sulfur atom is oxidized from -2 to +4. This is a change of 6 meaning 6 e - have been transferred. An oxygen atom is reduced from 0 to -2. This is a change of 2 or 2e - transferred. Because the substances are molecules, not atoms, we need to specify the change in the number of e - s per molecule 2.The next step is to determine the simplest whole numbers that will balance the number of electrons transferred for each reactant. The numbers become the coefficients of the reactants 1.The coefficients for the products can be obtained by balancing the atoms whose oxidation numbers have changed and then any other atoms.
22 Balancing Redox Equations using Oxidation Numbers #2 Example: Chlorate ions and iodine react in an acidic solution to produce chloride ions and iodate ions. Balance the equation for this reactions. ClO 3 - (aq) + I 2(aq) Cl - (aq) + IO 3 - (aq) 1.Assign oxidation numbers to all atoms/ions and look for the numbers that change. Highlight these. Remember to record the change in the number of electrons per atom and per molecule or polyatomic ion. 1.The next step is to determine the simplest whole numbers that will balance the number of electrons transferred for each reactant. The numbers become the coefficients of the reactants. The coefficients for the products can be obtained by balancing the atoms whose oxidation numbers have changed and then any other atoms. 2.Although Cl and I atoms are balanced, oxygen is not. Add H 2 O (l) molecules to balance the O atoms. 3.Add H + (aq) to balance the hydrogen. The redox equation should now be completely balanced. Check your work by checking the total numbers of each atom/ion on each side and checking the total electric charge, which should also be balanced.
23 Balancing Redox Equations using Oxidation Numbers #3 Example: Methanol reacts with permanganate ions in a basic solution. The main reactants and products are shown below. Balance the equation for this reaction. Assign oxidation numbers to all atoms/ions and look for the numbers that change. Highlight these. Remember to record the change in the number of electrons per atom and per molecule or polyatomic ion. Determine the simplest whole numbers that will balance the number of electrons transferred for each reactant. The numbers become the coefficients of the reactants. The coefficients for the products can be obtained by balancing the atoms whose oxidation numbers have changed and then any other atoms. Add H 2 O (l) to balance the oxygen, add H + (aq) to balance the hydrogen.
24 Balancing Redox Equations using Oxidation Numbers #4 Example: Household bleach contains sodium hypochlorite. Some of the hypochlorite ions disproportionate (react with themselves) to produce chloride ions and chlorate ions. Write the balanced redox equation for the disproportionation. For disproportionation reactions, start with two identical entities on the reactant side and follow the usual procedure for balancing equations.
25 Balancing Redox Equations using Oxidation Numbers #5 Example: A person suspected of being intoxicated blows into this device and the alcohol in the person s breath reacts with an acidic dichromate ion solution to produce acetic acid (ethanoic acid) and aqueous chromium(iii) ions. Balance the equation for this reaction. Remember to balance the C and Cr first, then add H 2 O (l) to balance O, H + (aq) to balance H and then stop because this is an acidic solution
26 Balancing Redox Reactions using Half- Reactions Rules for Writing Half-Reactions 1. Write an unbalanced ½ reaction showing formulas for reactants and products 2. Balance all atoms except H and O 3. Balance O by adding H 2 O (l) 4. Balance H by adding H + (aq) 5. Balance the charge by adding e - and cancel anything that is the same on both sides For basic solutions only: 6. Add OH-(aq) to both sides to equal the number of H+(aq) present 7. Combine H + (aq) and OH - (aq) on the same side to form H 2 O (l). Cancel equal amounts of H 2 O (l) from both sides.
27 Balancing Redox Reactions by Constructing Half-Reactions SUMMARY 1. Use the information provided to start two half-reaction equations. 2. Balance each half-reaction equation. 3. Multiply each half-reaction by simple whole numbers to balance electrons lost and gained. 4. Add the two half-reaction equations, cancelling the electrons and anything else that is exactly the same on both sides of the equation.
28 Balancing Redox Reactions by Constructing Half Reactions Example: A person suspected of being intoxicated blows into this device and the alcohol in the person s breath reacts with an acidic dichromate ion solution to produce acetic acid (ethanoic acid) and aqueous chromium(iii) ions. Predict the balanced redox reaction equation. Create a skeleton equation from the information provided: Separate the entities into the start of two half-reaction equations Now use the steps you learned for balancing half reactions Now, balance the electrons lost and gained, and add the half reactions. Cancel the electrons and anything else that is exactly the same on both sides of the equation.
29 Redox Terms Review: LEO the lion says GER Loss of electrons = entity being oxidized Gain of electrons = entity being reduced BUT. Chemists don t say the reactant being oxidized or the reactant being reduced Rather, they use the terms OXIDIZING AGENT (OA) and REDUCING AGENT (RA) OXIDIZING AGENT: causes oxidation by removing (gaining) electrons from another substance in a redox reaction REDUCING AGENT: causes reduction by donating (losing) electrons to another substance in a redox reaction What does this mean? Let s revisit our first example when zinc and hydrochloric acid reacted. Which reactant was reduced? Which was oxidized? So. Which is the Oxidizing Agent (OA)? Which is the Reducing Agent (RA) LEO = Oxidized GER = Reduced Zn (s) Zn 2+ (aq) + 2 e - 2 H + (aq) + 2 e - H 2 (g) Reducing Agent Oxidizing Agent
30 Redox Terms Silver ions were reduced to silver metal by reaction with copper metal. Simultaneously, copper metal was oxidized to copper(ii) ions by reaction with silver ions. If Ag + (aq) is reduced it is the: If Cu (s) is oxidized it is the: OXIDIZING AGENT (OA) REDUCING AGENT (RA) It is important to note that oxidation and reduction are processes, and oxidizing agents and reducing agents are substances.
31 REDOX Reactions so far Reduction Historically, the formation of a metal from its ore (or oxide) I.e. nickel(ii) oxide is reduced by hydrogen gas to nickel metal NiO (s) + H 2(g) Ni (s) + H 2 O (l) Ni +2 Ni o A gain of electrons occurs (so the entity becomes more negative) Electrons are shown as the reactant in the half-reaction A species undergoing reduction will be responsible for the oxidation of another entity and is therefore classified as an oxidizing agent (OA) Oxidation Historically, reactions with oxygen I.e. iron reacts with oxygen to produce iron(iii) oxide 4 Fe (s) + O 2(g) Fe 2 O 3(s) Fe 0 Fe +3 A loss of electrons occurs (so the entity becomes more positive) Electrons are shown as the product in the half-reaction A species undergoing oxidation will be responsible for the reduction of another entity and is therefore classified as an reducing agent (RA)
32 Redox Terms Summary so far: The substance that is reduced (gains electrons) is also known as the oxidizing agent The substance that is oxidized (loses electrons) is also knows as the reducing agent Question: If a substance is a very strong oxidizing agent, what does this mean in terms of electrons? The substance has a very strong attraction for electrons. Question: If a substance is a very strong reducing agent, what does this mean in terms of electrons? The substance has a weak attraction for its electrons, which are easily removed
33 Redox Table A reaction is considered spontaneous if it occurs on its own A reduction ½ reaction table is useful in predicting the spontaneity of a reaction Reduction Tables show reduction ½ reactions in the forward direction, therefore all the reactants will be oxidizing agents If we list the OA s from an experiment in decreasing order of strength, we create a reduction ½ reaction table: SOA Ag + (aq) + 1 e - Ag (s) Cu 2+ (aq) + 2 e - Cu (s) Zn 2+ (aq) + 2 e - Zn (s) Mg 2+ (aq) + 2 e - Mg (s) SRA
34 Building Redox Tables #1 Consider the following experimental information and add half-reactions to the redox table you have created Hg 2+ (aq) Cu 2+ (aq) Ag + (aq) Au 3+ (aq) Hg (s) Cu (s) Ag (s) Au (s) SOA Au 3+ (aq) + 3 e - Au (s) Hg 2+ (aq) + 2 e - Hg (s) Ag + (aq) + 1 e - Ag (s) Cu 2+ (aq) + 2 e - Cu (s) Zn 2+ (aq) + 2 e - Zn (s) Mg 2+ (aq) + 2 e - Mg (s) SRA
35 Building Redox Tables #1 SOA Au 3+ (aq) + 3 e - Au (s) Hg 2+ (aq) + 2 e - Hg (s) Ag + (aq) + 1 e - Ag (s) Cu 2+ (aq) + 2 e - Cu (s) Zn 2+ (aq) + 2 e - Zn (s) Mg 2+ (aq) + 2 e - Mg (s) SRA The spontaneity rule! A reaction will be spontaneous if on a redox table: OA above RA = Spontaneous below = Non-spontaneous RA Reaction OA Reaction
36 Building Redox Tables #2 Example 2: Use the following information to create a table of reduction ½ reactions OA RA 3 Co 2+ (aq) + 2 In (s) 2 In 3+ (aq) + 3 Co (s) OA RA Cu 2+ (aq) + Co (s) Co 2+ (aq) + Cu (s) Cu 2+ Co 2+ Pd (s) Co (s) OA RA Cu 2+ (aq) + Pd (s) no reaction In (s) SOA Pd 2+ (aq) + 2 e - Pd (s) Cu 2+ (aq) + 2 e - Cu (s) Co 2+ (aq) + 2 e - Co (s) In 3+ (aq) + 3 e - In (s) SRA
37 Building Redox Tables #3 Example 3: Use the following information to create a table of reduction ½ reactions OA RA 2 A 3+ (aq) + 3 D (s) 3 D 2+ (aq) + 2 A (s) OA RA G + (aq) + D (s) no reaction A 3+ D 2+ (aq) D (s) OA RA E (s) 3 D 2+ (aq) + 2 E (s) 3 D (s) + 2 E 3+ (aq) OA RA G + (aq) + E (s) no reaction G + SOA A 3+ (aq) + 3 e - A (s) D 2+ (aq) + 2 e - D (s) E 3+ (aq) + 3 e - E (s) G + (aq) + 1 e - G (s) SRA
38 Building Redox Tables So far we have been using examples where the oxidizing agents are metal ions and the reducing agents are metal atoms. What else could gain or lose electrons? Non-metal atoms I.e. Cl 2(g) + 2e - 2 Cl - (aq) (Cl 2(g) could act as a Reducing Agent) Non-metal ions I.e. 2 Br - (aq) Br 2(l) + 2 e - (2Br - (aq) could act as an Oxidizing Agent) Redox Table Trend OA s tend to be metal ions and non-metal atoms RA s tend to be metal atoms and non-metal ions Also, are there any entities that could act as both OA or RA? Multivalent metals
39 Example 4: Use the following information to create a table of reduction ½ reactions RA Ag (s) OA + Br 2(l) AgBr (s) Cl - RA OA Ag (s) + I 2(s) no evidence of reaction Br 2(l) Ag (s) OA RA Cu 2+ (aq) + I - (aq) no redox reaction OA RA Br 2(l) + Cl - (aq) no evidence of reaction I 2(s) Cu 2+ (aq) I - (aq) SOA Cl 2(g) + 2 e - 2Cl - (aq) Br 2(l) + 2 e - 2Br - (aq) Ag + (aq) + 1 e - Ag (s) I 2(s) + 2 e - 2I - (aq) Cu 2+ (aq) + 2 e - Cu (s) SRA
40 Predicting Redox Reactions Now that you know what redox reactions are, you will be responsible for determining if a reaction will occur (is spontaneous) and if so, what the reaction equation will be. How do we do this? 1. The first step is to determine all the entities that are present. Helpful reference: Table 5 pg. 680 Remember: In solutions, molecules and ions behave independently of each other. Example: When a solution of potassium permanganate is slowly poured through acidified iron(ii) sulfate solution. Does a redox reaction occur and what is the reaction equation?
41 Predicting Redox Reactions 2. The second step is to determine all possible OA s and RA s This is a crucial step!! Things to watch out for: Combinations (i.e. MnO 4 - (aq) is an oxidizing agent only in an acidic solution) To indicate this draw an arc between the permanganate and hydrogen ion Species that can act as both OA and RA Any lower charge multivalent metal i.e. Fe 2+, Cu +, Sn 2+, Cr 2+ Water (H 2 O (l) ) Label both possibilities in your list
42 Before we move on, let s practice Step 1 and 2 Pg. 680 #23
43 Pg. 680 #23
44 Pg. 680 #23
45 Predicting Redox Reactions 3. The third step is to identify the SOA and SRA using Appendix C11 (page 805) SOA SRA 3. The fourth step is to show the ½ reactions (from the redox table) and balance SOA equation straight from table. SRA equation read from right to left Are these equations balanced? Do the number of electrons lost = electrons gained If not, multiply one or both equations by a number then add the balanced equations
46 Predicting Redox Reactions 3. The last step is to predict the spontaneity. Does the net ionic equation represent a spontaneous or non-spontaneous redox reaction? If the SOA above Spontaneous SRA?? If the SRA below Nonspontaneous SOA
47 Predicting Redox Reactions #2 Could copper pipe be used to transport a hydrochloric acid solution? 1. List all entities 1. Identify all possible OA s and RA s 1. Identify the SOA and SRA 2. Show ½ reactions and balance 3. Predict spontaneity Since the reaction is nonspontaneous, it should be possible to use a copper pipe to carry hydrochloric acid
48 REDOX Reactions the end Reduction Historically, the formation of a metal from its ore (or oxide) I.e. nickel(ii) oxide is reduced by hydrogen gas to nickel metal NiO (s) + H 2(g) Ni (s) + H 2 O (l) Ni +2 Ni o A gain of electrons occurs (so the entity becomes more negative) Electrons are shown as the reactant in the half-reaction A species undergoing reduction will be responsible for the oxidation of another entity and is therefore classified as an oxidizing agent (OA) Decrease in oxidation number Oxidation Historically, reactions with oxygen I.e. iron reacts with oxygen to produce iron(iii) oxide 4 Fe (s) + O 2(g) Fe 2 O 3(s) Fe 0 Fe +3 A loss of electrons occurs (so the entity becomes more positive) Electrons are shown as the product in the half-reaction A species undergoing oxidation will be responsible for the reduction of another entity and is therefore classified as an reducing agent (RA) Increase in oxidation number
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Chapter 7: Chemical Equations Name: Date: Period: 7-1 What is a chemical reaction? Read pages 232-237 a) Explain what a chemical reaction is. b) Distinguish between evidence that suggests a chemical reaction
SNC2D Chemistry Review Name: Draw the Bohr-Rutherford diagram for each of the following atoms and determine the valence charge of their ions: Sodium: Aluminum: Sulfur: Fluorine: From your periodic table/chemistry
WRITING CHEMICAL FORMULA For ionic compounds, the chemical formula must be worked out. You will no longer have the list of ions in the exam (like at GCSE). Instead you must learn some and work out others.
Chapter 8: Chemical Equations and Reactions I. Describing Chemical Reactions A. A chemical reaction is the process by which one or more substances are changed into one or more different substances. A chemical
1 OXIDATION NUMBERS (Section 4.4) Oxidation number is the charge of an atom in a molecule if all the bonding is considered ionic. Oxidation number is different from formal charge. Using oxidation numbers
Introduction Chapter 5 Chemical Reactions and Equations Chemical reactions occur all around us. How do we make sense of these changes? What patterns can we find? 1 2 Copyright The McGraw-Hill Companies,
Chemical Reactions, Counting Atoms, and Balancing Chemical Equations. A Chemical Reaction is A process where one or more elements or compounds are changed into one or more different substances A process
Open the TI-Nspire TM document Balancing_Chemical_Equations_Practice.tns. In this activity you will use ChemBox feature of TI-Nspire TM technology to practice balancing chemical equations. Move to pages
Why? Types of Chemical Reactions Do atoms rearrange in predictable patterns during chemical reactions? Recognizing patterns allows us to predict future behavior. Weather experts use patterns to predict
1 Chemical Reactions Unit 8: Chemical Reactions and Equations What are chemical reactions and how do they occur? How are chemical reactions classified? How are products of chemical reactions predicted?
Chapter 7 Chemical Reactions Chemical & Physical Changes In a physical change, the chemical composition of the substance remains constant. Examples of physical changes are the melting of ice or the boiling
Q1. Identify each of the following half equations as involving either oxidation or reduction: a Na(s) Na + (aq) + e b Cl 2 (g) + 2e 2Cl (aq) c S(s) + 2e S 2 (aq) d Zn(s) Zn 2+ (aq) + 2e A1. a oxidation
HOMEWORK 4A Oxidation-Reduction Reactions 1. Indicate whether a reaction will occur or not in each of following. Wtiring a balcnced equation is not necessary. (a) Magnesium metal is added to hydrochloric
MOLE CONVERSION PROBLEMS 1. What is the molar mass of MgO? [40.31 g/mol] 2. How many moles are present in 34 grams of Cu(OH) 2? [0.35 moles] 3. How many moles are present in 2.5 x 10 23 molecules of CH
EPERIMENT 8: Activity Series (Single Displacement Reactions) PURPOSE a) Reactions of metals with acids and salt solutions b) Determine the activity of metals c) Write a balanced molecular equation, complete
4/15/13 Illustrate bonding Describe the signs of a chemical reaction and discuss chemical equations Find the charge of the ions below: (int: Ignore the neutrons and compare p and e) 1.5 protons, 6 electrons,
Balancing Reaction Equations Oxidation State Reduction-oxidation Reactions OCN 623 Chemical Oceanography Balanced chemical reactions are the math of chemistry They show the relationship between the reactants
CHAPTER 8 Chemical Equations and Reactions SECTION 1 Describing Chemical Reactions OBJECTIVES 1. List three observations that suggest that a chemical reaction has taken place. 2. List three requirements
-1- Inorganic Chemistry Writing (Net Ionic) Equations for Various Reactions On the AP examination you will encounter a question in which you will be required to write net ionic equations for various reactions.
Inorganic Nomenclature Chem 1-A Lab Lecture Spring 010 Chemical Formulas: the acronyms of chemistry Composed of element symbols, subscripts and sometimes parentheses Subscripts tell the number of atoms
Worksheet # 11 1. A solution of sodium chloride is mixed with a solution of lead (II) nitrate. A precipitate of lead (II) chloride results, leaving a solution of sodium nitrated. Determine the class of
1. Complete the following table: ATOMIC STRUCTURE Name Symbol # protons # neutrons # electrons Net charge Sodium ion Na +1 +1 Oxygen atom Gold ion +3 C Cl -1 Cesium ion +1 12 +2 16-2 18 +1 10 0 Ba +2 Helium
Name: Teacher: Pd. Date: STAAR Tutorial : Energy and Matter: Elements, Compounds, and Chemical Equations: 6.5C Differentiate between elements and compounds on the most basic level. 8.5F Recognize whether
à xidation numbers In the Lewis model of bonding, when nonidentical atoms are bonded together, an important consideration is how the bonding electrons are apportioned between the atoms. There are two different
Chemistry B11 Chapter 4 Chemical reactions Chemical reactions are classified into five groups: A + B AB Synthesis reactions (Combination) H + O H O AB A + B Decomposition reactions (Analysis) NaCl Na +Cl
Topics 1. Reaction Types a. Combustion b. Synthesis c. Decomposition d. Single replacement i. Metal activity series ii. Nonmetal activity series e. Double replacement i. Precipitates and solubility rules
Experiment 9 - Double Displacement Reactions A double displacement reaction involves two ionic compounds that are dissolved in water. In a double displacement reaction, it appears as though the ions are
Solutions for Practice Problems p. 114 Ch.4 Solutions 1. Consider the following reaction. 2H 2(g) + O 2(g) 2H 2 O (l) (a) Write the ratio of H 2 molecules: O 2 molecules: H 2 Omolecules. The ratio is given
Answers to Practice Problems 6.1, p. 226 1. This is a synthesis reaction (between a metal and a non-metal). The balanced chemical equation is: 2Li + Cl 2 2LiCl. 2. This is a synthesis reaction (between
8 CHEMICAL REACTIONS SECTION 8.1 DESCRIBING CHEMICAL CHANGE (pages 203 211) This section explains how to write equations describing chemical reactions using appropriate symbols. It also describes how to
Chemistry of Voltaic Cells An electrochemical cell consists of two parts, called half-cells, in which the separate oxidation and reduction reactions take place. Each half cell contains a metal electrode
EXPERIMENT 9: Double Replacement Reactions PURPOSE a) To identify the ions present in various aqueous solutions. b) To systematically combine solutions and identify the reactions that form precipitates
Experiment 5 Chemical Reactions OBJECTIVES 1. To observe the various criteria that are used to indicate that a chemical reaction has occurred. 2. To convert word equations into balanced inorganic chemical
Assessment Chapter Test A Chapter: Chemical Equations and Reactions In the space provided, write the letter of the term or phrase that best completes each statement or best answers each question. 1. You
Using the Periodic table: Main Group Main Group Elements 1 Using the Periodic Table:Transition Group Transition Metals Form various cations by loss of electrons e.g. Fe 2+ / Fe 3+, Cu + / Cu 2+ Cr 2+ /
AP Chem Summer Assignment Worksheet #1 Atomic Structure 1. a) For the ion 39 K +, state how many electrons, how many protons, and how many 19 neutrons are present? b) Which of these particles has the smallest
APPENDIX A Molarity of Ions in Solution ften it is necessary to calculate not only the concentration (in molarity) of a compound in aqueous solution but also the concentration of each ion in aqueous solution.