Exam 3

Question 1

how do we measure the strength of an acid

Answer 1

tendency to ionize

Question 2

what are the two factors the influence the extent which an acid undergoes ionization

Answer 2

1. strength of the bond between hydrogen and other molecule
2. polarity between H and other element (difference in electronegativity) highly polar = strong acid

Question 3

hydrohalic acids

Answer 3

binary acids from halogen series (HF, HCl, HBr, HI) which only HF is a weak acid
- predominant factor to determine strength of acid is the strength of the bond
HF<HCl<HBr<HI

Question 4

oxoacids: hydrogen, oxygen, and central nonmental atom

Answer 4

if central atom is electronegative or has high oxidation state it will attract electrons causing O-H bond to be more polar making it easier for H+ to leave and making it a strong acid

1. if oxoacids have different central atoms but from same group on periodic table (which means same oxidation number) look at which is more electronegative
2. oxoacids with same central atom but different number of oxygen atoms: electronegativity increases with more oxygen atoms (the one with the most oxygen with be the strongest acid)

Question 5

carboxylic acids

Answer 5

have an acid molecule with the carboxyl group (-COOH)
the conjugate base of a carboxylic acid is a carboxylate anion (RCOO-) the more stable this anion is from electron delocalization the greater tendency for the acid to ionize

Question 6

what is auto-ionization of water

Answer 6

what is amphoteric - it can act as both a base and an acid. When two water molecules reaction with each other they form hydronium ion (H3O+) and hydroxide (OH-). The reaction would have equilibrium arrow

Question 7

what is Ka and Kb for?

Answer 7

its the same as Kc just specific to equilibrium constant for weak acids and bases

Question 8

ionization of a strong acid

Answer 8

strong acids completely ionize and go to completion - this means they would not have double arrows in the reaction equation only a single arrow from reactants to products

• the concentration of hydronium (H3O+) ions is equal to the starting concentration of the strong acid

Question 9

at equilibrium - what is present in an aqueous solution with weak acid

Answer 9

aqueous acid, hydronium, and conjugate base

Question 10

what does the value of Ka indicate

Answer 10

high Ka = strong acid
low Ka = weak acid