Chapter 4 Chemistry Review Aqueous Reactions and Solution Stoichiometry By: Enid Truong and Alyisha...
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Transcript of Chapter 4 Chemistry Review Aqueous Reactions and Solution Stoichiometry By: Enid Truong and Alyisha...
![Page 1: Chapter 4 Chemistry Review Aqueous Reactions and Solution Stoichiometry By: Enid Truong and Alyisha Bouges.](https://reader036.fdocuments.in/reader036/viewer/2022082817/56649e675503460f94b61f47/html5/thumbnails/1.jpg)
Chapter 4 Chemistry Review
Aqueous Reactions and Solution Stoichiometry
By: Enid Truong and Alyisha Bouges
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Electrolytes
A substance whose aqueous solution contains ions. The more ions present the stronger the solution. Ex:NaCl
Nonelectrolyte: a substance that does not form ions Ex: C12H22O11
Strong vs. Weak
• Strong = completely ionized, all Ionic compounds and the strong molecular acids
• Weak = some amount ionizes, weak acids and bases
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Electrolytes
Dissolution?
When an ionic compound dissolves in water.
Solvation?
When water molecules surround an ion to stop them from rebonding.Denoted with an aqueous phase abbreviation: (aq)
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Precipitates
A reaction that results in the formation of an insoluble product are called Precipitation Reactions.
A precipitate is an insoluble solid that is formed in a reaction
Ex:KI (aq) + Pb(NO3)2 (aq) ---> PbI2 (s) + 2KNO3 (aq)
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Solubility Rules!
Which of the pair is insoluble (will be solid)?
• Na2SO4 or BaS
• KOH or CaCl2
• MgCrO4 or LiClO3
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Solubility Rules!
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Net Ionics
CaCl2 (aq) + Na2CO3 (aq) ---> CaCO3 (s) + 2NaCl (aq)
Write the net ionic and find the precipitation reaction that occurs when aqueous solutions of Calcium Chloride and Sodium Carbonate are mixed.(as seen above)
Ca^2+(aq) + CO3^2+(aq) ------> CaCO3(s)
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Acids vs. Bases
Acids:
• H+
• Proton donor
• Ex: HCl(monoprotic)H2SO4(diprotic)H3P(triprotic)Bases:
• OH-
• Proton acceptor
• Ex: Al(OH)3
Strong acids and bases are strong electrolytes, so they ionizes completely. Weak acids and bases do not.
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Acids vs. Bases
Ways to remember:
Our favorite for strong acids: http://www.youtube.com/watch?v=jPilrd7b1B8
Something new for strong bases: The Thumb Rule
(AKA: The Rule of Thumb)
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Neutralization Reactions
When you add an acid to a base, the result is water and a salt.
Ex: HCl (aq) + NaOH (aq) ---> H2O (l) + NaCl (aq)
Try one!! Magnesium hydroxide and hydrochloric acid. What do they form?
H2O(l) + MgCl2(aq)
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Acid-Base Gas FormationsSulfide ion and Carbonate ions both from
gas when they react with acids. For example:
2HCl(aq) + Na2S(aq) --->H2S(g) + 2NaCl(aq)
But what does this produce?Na2SO3(aq) + HCl(aq)----> ?
NaCl(aq) + H2SO4
H2O(l) + SO2(g)
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Oxidation-Reduction
AKA :REDOX Reactions
Oxidation - the LOSS of electrons by a substance.Reduction - the GAIN of electrons by a substanceGreat way to memorize this: LEO says GER (Lose
Electron Oxidizes/ Gains Electrons Reduces)
Which one reduces and which one oxidizes? :
Ca(s) + 2 H^+(aq) ---> Ca2^+(aq) + H2(g)
oxidized!
Reduced!
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Oxidation Numbers
1) For an Atom in its elemental form, the oxidation number is always zero
EX: H2 has an oxidation number of 0
2) For any Monatomic ion the oxidation number equals the charge on the ion
EX: K+ has an oxidation number of +1 and S2- has an oxidation number of -2
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Oxidation Numbers
3) Nonmetals usually have negative oxidation numbers, but they can be positive with some exceptions:
1) The oxidation number of oxygen is usually -2 in both ionic and molecular compounds. The exception is in peroxides (O2)^2-, giving each oxygen a charge of 1-.
For ex: BaO2 ; (1)(-2) + (2)(x) = 0 ; O = -1
2) The oxidation of Hydrogen is usually +1 when bonded to nonmetals and -1 with metals
For ex: NaH ; Na is a metal, so in this case, the ox. number of H is -1
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Oxidation Numbers
3) The oxidation number of fluorine is -1 in all compounds. Other halogens have an ox. number of 1- in most binary compounds, but when combined with oxygen, they have positive ox. numbers.
4) The sum of the oxidation numbers of all atoms in a neutral compound is zero. The sum of the ox. number of polyatomic ions equals the charge of the ion.
For ex: (Cr2O7)^ -2 Cr is unknown, but we know O has an oxidation number of -2, so (x)(2) + (-2)(7) = -2. Cr = -1
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Molarity
Molarity (M) = Moles solution / volume of solution in liters
Problem: What is the molar concentration of K+ ions in a o.o15M solution of potassium carbonate?
0.030M
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Dilution and Titration
McVc = MdVd (where c = concentrate & d = dilute)
Titration: a method scientists often use to determine the concentration of a particular solute in a solution..
MaVaIa = MbVbIb (M stands for molarity, V stands for volume, I stand for ions, a = acids and b = base) To find "I" look at the amount of H+ and OH- ions
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Activity Series
Take out your Super Secret Periodic Tables and turn to page 39.
This is your table of the activity series.Which is a list of metals arranged in
order of decreasing ease of oxidation and to form compounds.
Any metal on the list can be oxidized by the element below it!
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Activity Series
Now answer this:
If you add copper to a solution with silver present, will there be a reaction?
Yes!
Now what if gold were added to the same solution?
No!