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What is a phenomenon?
It is a fact or a situation that is observed to exist or happen.
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Define Electrochemistry?(also prove its simple definition)
The branch of chemistry that deals with the relation between electrical and chemical phenomena (occurrence/happening).
- Electrochemistry is the study of the flow of electrons
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Define electrons
An electron is a tiny particle of matter than an atom and has a negative electric charge.
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Define Reduction?
A process by which electrons are gained by an entity
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Define Oxidation?
A process by which electrons are lost by an entity
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Redox reactions examples (6)?
which reaction can’t be an example of a redox reaction.
- Formation, decomposition, combustion, single replacement, cellular respiration, photosynthesis (but not double replacement)
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Define Half reaction(s)
Half reaction(s) is a balance chemical equation which represents the gain or loss of electrons by a substance.
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Define Reduction Half Reactions
The electrons are on the reactant side of the equation
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Define Oxidation Half Reaction
The electrons are on the product side of the equation
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What are the thing you need to know about Adding or cancelling reactants or products of half reactions (4pts)
- - Half reactions can be manipulated similar of Hess’ law
- - Coefficients of half-reactions can be altered by multiplying or dividing by a constant factor to make the number of electrons gained equal the number of electrons lost.
- - When electrons gained equal the electrons lost, the substance can be added up (like in Hess law)
- - The equation that remains is called the net ionic equation
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Define Reducing Agent (2pts)
- - The substance that causes the reduction of another substance
- - The substance (the RA) undergoes oxidation
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Define Oxidizing Agent (2pts)
- - The substance that causes the oxidation of another substance
- - The substance (The OA) undergoes reduction
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Define what a Redox reaction is (2pts)
- - A chemical reaction in which electrons are transferred
- - Must have both reduction and oxidation happening for the reaction to occur.
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Define Ionic compounds (2pts)
- - A bond formed between a metal and a non metal (metal goes first)
- - Atoms are electrically attracted to each other and energy/electrons are transferred
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Define Molecular compounds (2pts)
- - A bond formed between a nonmetal and a nonmetal
- - a bond in which atoms (nonmetals) are joined by covalent bonds
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Define Covalent bonds
- a bond formed between two or more nonmetals by sharing (outermost ring) electrons:valence electrons
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Define Polyatomic ions
- are compounds composed of two or more atoms (metals or nonmetals) that are covalently bonded and has an overall charge
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Define Molten
(Especially of materials with high melting point such as metal and glass) Liquified by heat/melted
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Define Electrolysis
Chemical decomposition produced by passing electric current through a liquid or solution containing ions.
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Oxidation State is defined as
Is defined as the net electric charge an atom would have if the electron pairs in a covalent bond belonged entirely to the most electronegative atom.
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Define Oxidation Number
An oxidation number is a positive r negative number corresponding to the oxidation state of the atom in a compounds
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The commons of oxidation numbers
1) All atoms in elements have an oxidation number of?
2) Hydrogen in all compounds have an oxidation number of ___ except for hydrides which has __
3) Oxygen in all compounds have an oxidation number of __ except in peroxides which has __
4) All monatomic ions have an oxidation number of?
- 1) have 0 charge
- 2) have +1 charge, have -1 charge
- 3) have -2 charge, have -1 charge
- 4 charge on ions
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How do you determine the oxidation number of an unknown element in a polyatomic compound? Provide an example
- When you have a metal with a polyatomic ion, treat them as separate and use the charge of the metal to determine the charge of unknown
- Eg: KMnO4 (the unknown is MnO4)
- K is +1 = MnO4 must be -1
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How do you solve Oxidation numbers and Redox problems? (3pts)
- 1) Write the chemical equation
- 2) Determine all the oxidation numbers
- 3) Label atoms/ions as reduction or oxidation
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What is the Redox Spontaneity Rule and when do we use it?
Redox Spontaneous rule - a spontaneous redox reaction will occur if the oxidizing agent (OA) is above the reducing agent (RA) in the table of reduction half reactions.
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What does a spontaneous and non spontaneous redox reaction mean?
- Spontaneous reactions - product will form
- Non spontaneous reactions - product will not form
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What are the 2 ways of using the Spontaneity Rule?
- 1) Generate a table of reduction half reactions
- 2) Predict which redox reaction will occur (5 step method)
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In Predicting Redox Reactions how do you Generate a table of Reduction Half reactions? (5pts)
- 1) If the reaction is Spontaneous OA/RA
- - label the OA and RA
- 2) if the reaction is Non-Spontaneous RA/OA
- - label the OA and RA
- 3) When all reactions provided have been evaluated an order can be established for all OA’s and RA’s
- 4 Write the Reduction Half Reaction for the each OA in the proper order
- 5) label the table SOA at the top left corner and SRA at the bottom right corner.
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Define SOA and what does it stand for?
- SOA acronym for Strongest Oxidizing agent, the higher an element is on the left side of the reduction half reactions table (pg 7 of data booklet) the stronger oxidizing Agent it is.
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Define SRA and what does it stand for?
- SRA acronym for Strongest Reducing Agent, the lower an element is on the table of Reduction half reactions (pg 7 of databooklet) the stronger reducing agent it is.
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When is a reaction considered spontaneous (not asking about how OA has to be Over RA)
A reaction is considered spontaneous when it occurs by its own
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What are 2 Redox Table trends? (2pts)
- - OA’s (left side) tend to be metal ions and nonmetal atoms
- -RA’s (on right side) tend to be metal atoms and non metal ions
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Can some entities act as both OA and RA in a reduction half reaction, if so which ones? (5pts)
- Yes, some entities can act as both OA and RA
- - Fe2+
- - Cr2+
- - Sn2+
- - Cu+
- - H20
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When using the 5 step method for predicting Redox reactions there are hints for labelling entities (that is important for step 1), what are the following hints? (5pts)
- - Aqueous Solution contains H2O(l) molecule
- - Acidic Solution contains H+1(aq) ions
- - Basic Solution contains OH-1(aq) ions
- - Some oxidizing and reducing Agents are combinations, for example MnO4-1 (so don’t separate them)
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What is The 5 step method when predicting redox reactions? (5pts)
- 1) Determine all entities that are present in the question (keep in mind the hints for labelling entities)
- 2) Determine all the possible OA’s and RA’s
- 3) Determine the SOA and SRA
- 4) Show the reduction half reactions of the SOA and SRA and balance the electrons gained and lost. Write the net ionic equation
- 5) Predict spontaneity, determine whether or not the reaction is spontaneous (will occur) or non spontaneous (will not form products/not occur)
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Define Titration
It s a common laboratory process used to determine the concentration of a known substance
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Define stoichiometry
It is the study of the reactants and products involved in a chemical reaction
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What are the 4 steps use to solve stoichiometry problems
- 1) balance the chemical equation
- 2) Convert units of a given substance to mole n=cv n=m/M
- 3) use the mole, calculate the moles you ave and multiply it with (mole ratio) Want/have to get the mole of the other substance
- 4) Convert moles to find the unknown
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Define titrant
A solution of a known concentration that is added (titration) to another solution to determine the concentration of a second chemical species
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In redox reactions, what do we do when the half reactions is not provided to us/not in pg 7of data booklet?
What are the rules for writing half reactions
We creat our own table
- Rules for writing Half-Reactions
- 1) write an unbalanced chemical equation, showing formulas for the reactants and products
- 2) Balance all atoms except H and O
- 3) Balance O by adding H2O(l) to the other side
- 4) Balance H by adding H+(aq) to the other side
- 5) balance the charge by adding e- and cancel anything that is the same on both sides
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