CHEM 1150 Lecture Notes - Limiting Reagent, Molar Concentration, Alkali Metal
She only cares about balancing atoms
-
Steps:
○
General tips and hints:
Start w/ atoms in most complex substance (and end w/ simplest
substance like H2)
§
Take one element at a time, working left to right (or vice versa)
§
Balance oxygen in a combustion reaction last (it will occur in
multiple reactants or products)
§
Polyatomic ions that appear on both sides of equation should be
balanced as independent units
§
It is useful to use fractions when balancing, but make it clear when
multiplying entire equation by the denominator!
§
Check your atoms!
§
○
-
Stoich
Molar ratio: 1 of CO2for every 2 moles O2(get out of the equation)
○
Limiting reagent/ reactant: g of reactant of MM * (# of mole of product of
interest/ # mole of reactant) and then compare the two to determine
limiting reactant
Multiply moles of product by product of interest by its MM to
get its theoretical yield
□
§
Use LR to use how much ER is used and how much is left over
§
Percent yield= (actual yield/ theoretical yield)*100
Side reactions
®
□
§
○
-
Molarity
M= moles/ liter
○
M1V1= n = M2V2
○
-
Ions in water
Solute:
○
Solvent:
○
Ex. 5 mol ammonium sulfate dissolved in water
(NH4)SO4(s) --> 2NH4+(aq) + SO42-(aq)
Good to understand for test: oxygen is the negative part of
the water, and H is the partial/ positive part (b/c H2O
supposed to be over -->)
□
Solve for ions (products) using stoich.□
§
○
-
Types of reactions:
Precipitation reactions:
Double displacement
§
○
Acid base reaction
Gas evolution reaction (bubbles formed)
§
§
§
Make a salt (aq) and water (l)
§
○
Oxidation reduction reactions (redox reactions)
Decomposition/ combination reactions
§
Single displacement reactions
§
Combustion reactions
§
○
Predicting reactions
○
Titration
Neutralization reactions (w/ burette)
○
○
Solubility rules
Water is universal solvent
§
Thing in excess: solvent
§
(aq)= soluble (dissociates)
§
HAVE TO MEMORIZE
Group 1A: alkali metals: will always be soluble no
matter what
Also NH4+, NO3-, ClO4-
◊
®
Cl-, Br-, I-soluble with Ag+, Pb2-, Cu+
®
CO32- and PO43- insoluble EXCEPT alkali metals and NH4+
®
OH-insoluble EXCEPT alkali metals, NH4+, Ca2+, Sr2+, Ba2+
®
S2- insoluble EXCEPT alkali metals, alkali earth metals,
and NH4+
®
□
§
Aqueous ionic reactions
◊
§
○
-
Oxidation reaction
○
If 2 of a compound, don't get tripped up
○
What loses e- is oxidized (b/c becomes more +), what gains e- is reduced
(b/c becomes more -)
What loses e- is reducing agent (oxidized), what gains e- is oxidizing
agent (reduced)
§
○
LEO says GER
Loose e- Oxidized
§
Gain e- Reduced
§
○
-
Chapter 4: Chemical rx's and stoich: chem rxn's and
stoich
Monday, February 5, 2018
10:46 AM
She only cares about balancing atoms
-
Steps:
○
General tips and hints:
Start w/ atoms in most complex substance (and end w/ simplest
substance like H2)
§
Take one element at a time, working left to right (or vice versa)
§
Balance oxygen in a combustion reaction last (it will occur in
multiple reactants or products)
§
Polyatomic ions that appear on both sides of equation should be
balanced as independent units
§
It is useful to use fractions when balancing, but make it clear when
multiplying entire equation by the denominator!
§
Check your atoms!
§
○
-
Stoich
Molar ratio: 1 of CO2for every 2 moles O2(get out of the equation)
○
Limiting reagent/ reactant: g of reactant of MM * (# of mole of product of
interest/ # mole of reactant) and then compare the two to determine
limiting reactant
Multiply moles of product by product of interest by its MM to
get its theoretical yield
□
§
Use LR to use how much ER is used and how much is left over
§
Percent yield= (actual yield/ theoretical yield)*100
Side reactions
®
□
§
○
-
Molarity
M= moles/ liter
○
M1V1= n = M2V2
○
-
Ions in water
Solute:
○
Solvent:
○
Ex. 5 mol ammonium sulfate dissolved in water
(NH4)SO4(s) --> 2NH4+(aq) + SO42-(aq)
Good to understand for test: oxygen is the negative part of
the water, and H is the partial/ positive part (b/c H2O
supposed to be over -->)
□
Solve for ions (products) using stoich.□
§
○
-
Types of reactions:
Precipitation reactions:
Double displacement
§
○
Acid base reaction
Gas evolution reaction (bubbles formed)
§
§
§
Make a salt (aq) and water (l)
§
○
Oxidation reduction reactions (redox reactions)
Decomposition/ combination reactions
§
Single displacement reactions
§
Combustion reactions
§
○
Predicting reactions
○
Titration
Neutralization reactions (w/ burette)
○
○
Solubility rules
Water is universal solvent
§
Thing in excess: solvent
§
(aq)= soluble (dissociates)
§
HAVE TO MEMORIZE
Group 1A: alkali metals: will always be soluble no
matter what
Also NH4+, NO3-, ClO4-
◊
®
Cl-, Br-, I-soluble with Ag+, Pb2-, Cu+
®
CO32- and PO43- insoluble EXCEPT alkali metals and NH4+
®
OH-insoluble EXCEPT alkali metals, NH4+, Ca2+, Sr2+, Ba2+
®
S2- insoluble EXCEPT alkali metals, alkali earth metals,
and NH4+
®
□
§
Aqueous ionic reactions
◊
§
○
-
Oxidation reaction
○
If 2 of a compound, don't get tripped up
○
What loses e- is oxidized (b/c becomes more +), what gains e- is reduced
(b/c becomes more -)
What loses e- is reducing agent (oxidized), what gains e- is oxidizing
agent (reduced)
§
○
LEO says GER
Loose e- Oxidized
§
Gain e- Reduced
§
○
-
Chapter 4: Chemical rx's and stoich: chem rxn's and
stoich
Monday, February 5, 2018
10:46 AM
Document Summary
Chapter 4: chemical rx"s and stoich: chem rxn"s and stoich. Start w/ atoms in most complex substance (and end w/ simplest substance like h2) Take one element at a time, working left to right (or vice versa) Balance oxygen in a combustion reaction last (it will occur in multiple reactants or products) Polyatomic ions that appear on both sides of equation should be balanced as independent units. It is useful to use fractions when balancing, but make it clear when multiplying entire equation by the denominator! Molar ratio: 1 of co2 for every 2 moles o2 (get out of the equation) Limiting reagent/ reactant: g of reactant of mm * (# of mole of product of interest/ # mole of reactant) and then compare the two to determine limiting reactant limiting reactant. Multiply moles of product by product of interest by its mm to get its theoretical yield.
