CEM 142 Exam 2 Cangelosi
% Ionization - ANS-About what number of water molecules are ionized at 25 celsius (in pure
water) ?
% ionization = (1x10^-7 M/55.5M) x a hundred
=1.8x10^-7
1. What is the conjugate acid of H2O?
2. What is the conjugate base of H2O? - ANS-1. H3O+
2. HO-
1. What is the Oxidation # of N in NH3?
2. What is the Oxidation # of H in NH3?
Three. What is the Oxidation # of N in NH4+?
4. What is the Oxidation # of H in NH4+? - ANS-1. -three
2. +1
3. -three
4. +1
2H2 + O2 -> 2H2O - ANS-VERY exothermic reaction: ΔH = -286 kJ/mol
- rocket fuel!
2 H-H + O=O -> 2 H-O-H
For this reaction to occur we should - Break H-H bonds and O=O bonds
- Form O-H bonds
So which tactics require electricity and which of them produce strength? Requires power to
break HH and OO bonds and produces strength to shape the brand new bonds
A Lewis Acid-Base Complex - ANS-
A word about H+ - ANS-There isn't any such issue as H+ (in aqueous solution).
H+ is a completely small quite charges species - it is always surrounded by way of a number of
water molecules (a salvation shell)
The Hydronium ion (H3O+) is a higher way to represent H+
BUT - if you see H+ you should expect H3O+
, A answer of HCl(g) in water (HCl(aq)) conducts energy.
What does that inform you about the character of the solution? - ANS-There MUST be ions
present in solution!
Acetic acid - ANS-
Acid Base Reactions - ANS-Several fashions of acid base reactions: From simple (with
constrained utility)...
...To complicated (with extensive application)
Acid electricity (in water) relies upon on: - ANS-The enthalpy exchange whilst added to water
-The energy of the H-X bond
-The balance of the X- conjugate base
The entropy alternate while brought to water
Acid Strength Increases Down a Group - ANS-HF<HCl<HBr<HI
This is both an enthalpic and entropic effect
Acid strength is increased... - ANS-If the conjugate base can be stabilized - by "spreading it out"
over several atoms.
*Strong acids have weak conjugate bases*
Examples:
Compare CH3COOH to CH2CH2OH
H2SO4 is a strong acid
HNO3 is a strong acid
All reactions are accompanied by energy changes - ANS-We use this energy for lots of
purposes:
- Combustion (oxidation of hydrocarbons) to heat houses and drive cars.
- Food is oxidized in our bodies - the energy is used to drive other reactions (and us!).
Where does this energy come from?
Where does it go?
Arrhenius Acid and Base Examples
Common Arrhenius acids?
Common Arrhenius bases?
KNOW - ANS-Common Arrhenius acids: HCl, HNO3, H2SO4, H3PO4, HClO4, H2CO3
% Ionization - ANS-About what number of water molecules are ionized at 25 celsius (in pure
water) ?
% ionization = (1x10^-7 M/55.5M) x a hundred
=1.8x10^-7
1. What is the conjugate acid of H2O?
2. What is the conjugate base of H2O? - ANS-1. H3O+
2. HO-
1. What is the Oxidation # of N in NH3?
2. What is the Oxidation # of H in NH3?
Three. What is the Oxidation # of N in NH4+?
4. What is the Oxidation # of H in NH4+? - ANS-1. -three
2. +1
3. -three
4. +1
2H2 + O2 -> 2H2O - ANS-VERY exothermic reaction: ΔH = -286 kJ/mol
- rocket fuel!
2 H-H + O=O -> 2 H-O-H
For this reaction to occur we should - Break H-H bonds and O=O bonds
- Form O-H bonds
So which tactics require electricity and which of them produce strength? Requires power to
break HH and OO bonds and produces strength to shape the brand new bonds
A Lewis Acid-Base Complex - ANS-
A word about H+ - ANS-There isn't any such issue as H+ (in aqueous solution).
H+ is a completely small quite charges species - it is always surrounded by way of a number of
water molecules (a salvation shell)
The Hydronium ion (H3O+) is a higher way to represent H+
BUT - if you see H+ you should expect H3O+
, A answer of HCl(g) in water (HCl(aq)) conducts energy.
What does that inform you about the character of the solution? - ANS-There MUST be ions
present in solution!
Acetic acid - ANS-
Acid Base Reactions - ANS-Several fashions of acid base reactions: From simple (with
constrained utility)...
...To complicated (with extensive application)
Acid electricity (in water) relies upon on: - ANS-The enthalpy exchange whilst added to water
-The energy of the H-X bond
-The balance of the X- conjugate base
The entropy alternate while brought to water
Acid Strength Increases Down a Group - ANS-HF<HCl<HBr<HI
This is both an enthalpic and entropic effect
Acid strength is increased... - ANS-If the conjugate base can be stabilized - by "spreading it out"
over several atoms.
*Strong acids have weak conjugate bases*
Examples:
Compare CH3COOH to CH2CH2OH
H2SO4 is a strong acid
HNO3 is a strong acid
All reactions are accompanied by energy changes - ANS-We use this energy for lots of
purposes:
- Combustion (oxidation of hydrocarbons) to heat houses and drive cars.
- Food is oxidized in our bodies - the energy is used to drive other reactions (and us!).
Where does this energy come from?
Where does it go?
Arrhenius Acid and Base Examples
Common Arrhenius acids?
Common Arrhenius bases?
KNOW - ANS-Common Arrhenius acids: HCl, HNO3, H2SO4, H3PO4, HClO4, H2CO3
