Chemistry Flashcards
(52 cards)
What is Paramagnetism?
Electrons align with the magnetic fields and then return to orientation in absence of magnetic fields.
What is Diamagnetism?
Electrons resist alignment with magnetic field even in presence of an external magnetic field.
What is Ferromagnetism?
Electrons are strongly aligned even in absence of an external magnetic field.
What is the relationship between Keq and ∆G?
They are opposites within the same process. When Keq is greater than 1, then ∆G is less than 1 and this would be a spontaneous reaction. Vice Versa is to be assumed.
Arrhenius definition only works with…
Water! It can be applied only to reactions that occur in water because it defines acids and bases in terms of what happens when compounds dissolve in water.
What are the Arrhenius base and acid rules?
Arrhenius Acids are hydronium ion donors. Arrhenius Bases are hydronium ion acceptors. Hydronium is H3O+..
pH = ?
pH = -log (H+) or pOH = -log (OH-)
What is the relationship between Acids/Bases and their conjugates?
Strong acids make weaker conjugate bases. Weaker acids make stronger conjugate bases.
What are the Strong Acids to memorize?
HCl, HBr, HI, H2SO4 (sulfuric acid), HNO3 (nitric acid), HClO3 (chloric acid), HClO4 (perchloric acid)
What are the Weak Acids to memorize?
CH3COOH (acetic acid), H2CO3 (carbonic acid), HCN (hydrocyanic acid), HF, H3PO4 (phosphoric acid)
What are the Strong Bases to memorize?
NaOH, KOH, CsOH, Ca(OH)2, Ba(OH)2, Sr(OH)2, hydroxides made from group 1 (alkali) metals
What are the Weak Acids to memorize?
NH3 (ammonia), NH4OH (ammonium hydroxide), C5H5N (Pyridine)
What is the reduction potential?
Measured in volts and its energy per amount of charge. The tendency of a chemical to be reduced by gaining an electron. Higher electronegativity means higher reduction potential. Negative reduction potentials mean movement from positive side of battery to the negative.
AN OX
RED CAT
Electrons ALWAYS move from the anode to the cathode. The anode is oxidation and the cathode is reduction. Anions move toward the anode and cations move to the cathode.
Galvanic Cell
- Gets energy from spontaneous redox reactions
- Eₒ is positive
- ∆G is negative
- Cathode is (+)
- Anode is (-)
Electrolytic Cell
- Requires DC battery or AC source
- Eₒ is negative
- ∆G is positive
- Cathode is (-)
- Anode is (+)
Nucleophilic Addition
A nucleophile forms a sigma bond with an electron-deficient species. Can’t take place in the presence of excessive steric hinderance.
3 Steps:
1. Electrophilic carbonyl carbon bonds with nucleophile
2. Carbon-oxygen double bond is now broken, forming an alkoxide intermediate (oxygen has a negative charge).
3. Alkoxide gets protonated, making alcohol that is also attached to the nucleophile
Electrophile vs. Nucleophile
Electrophiles are lewis acids with positive charges. Nucleophiles are lewis bases with negative charges and they can use their electrons to make new bonds.
Aldehydes are better electrophiles than ketones.
What make the best Leaving Groups?
- Stable on its own
- Weakest bases and low energy
- Can take electrons and be stable with that negative charge or can spread out the negative charge
Examples: Water, alcohol, ethers, halides (the bigger the better), inorganic esters (H2PO4, HNO3), tosylates
Note: Anhydrides are good leaving groups as well
What makes the weakest Leaving Groups?
- Not stable
Example: hydroxides, alkoxides, carbanions, hydride (H-)
The relationship between pKa and acidity is…
pKa and acidity are inverse. As the pKa lowers, the acidity increases. The more positive the more acidic, the more negative the more basic.
What is the difference between polar protic and polar aprotic solvents?
Polar Protic: have protons and hydrogen bonding, the nucleophilicity of the halides increases down the table
Polar Aprotic: have no electrons to donate and no hydrogen bonding, the nucleophilicity of the halides increases up the table
Geminal and Vicinal Hack!
Gemini twins - Geminal
Same Vicinity - Vicinal
Aldol Condensation
When you add a base to a ketone, an enolate will be formed. Then, if you react this enolate with a ketone, it will become an aldol.
Enolates have a C=C bond with one of the carbons being bonded to an oxygen-carrying the negative charge.
