Acids And Bases Flashcards
Difference between the Lewis and the bronsted Lowry definitions
Lewis is more broad - acid accepts electrons “electrophile” , base donates a pair of electrons “nucleophile”… this is more used in organic chem
Bronsted: acid donates a H , base accepts a proton … this is more used in general chem
List the strong acids you need to know
HCL HBr HI H2S04 HN03 nitric HCl03 HCl04
List strong bases you need to know
NaOH KOH CaO Na2O H CaOH2 BaOH2 SrOH2
Strong acid or base = _____ conjugate
Weak
Weak acid/base = ____ conjugate
Strong or weak
How does acidity increase on the periodic table
Increase across a period left to right and down a group
Because more electronegative conjugate base can better handle a negative charge. Increased size can spread out the negative charge *** size trumps electronegativity
How does resonance affect acidity
Electron is spread over several atoms so better stabilized conjugate base = more acidic
Explain inductive effects on the stability of an acid
Electron withdrawing groups weaken bond with H and stabilize conjugate base
Consider the nature of the group(more electronegative better), the number of them (more the better), and the proximity to the hydrogen (closer better)
Protonation states of amino acids
COOH pka = 2 deprotonated at ph = 7
NH3 pka = 9 protonated at ph = 7
What is the water equilibrium constant
Kw = 1 x 10 -14 = H30 x OH
Log 3.6
0.5
Log 5
0.7
When do we have to consider autoionization and what does that mean
When we have very little concentration of strong acid ie <1x10-7
Have to include it in the calculation of pH
H20 + H20 = H30 + OH
*** if the concentration of the acid is >1x10-7 can ignore water in the equation
What happens to Ka in a polyprotic acid
Decreases an ionizations becomes more difficult
What is the pH of a polyprotic acid and what’s the exception
PH = [h30] from the first ionization step
H2S04 have to account for HS04 as well because it has a substantial Ka
What is the relationship between Ka, pKa, and pH
Ka > 1 pKa will be negative
Ka = 1 pKa will be 0
Ka < 1 pKa will be positive
** higher Ka = stronger acid
Explain the reaction between a strong acid and a weak base
Forms a water and salt with two ions in solution. The weak base will react with water as a weak acid in a hydrolysis reaction to form a conjugate base and hydronium ion
Strong acid + weak base = acidic salt where cation is acidic and anion is neutral
Explain the reaction between a strong base and weak acid
Forms a basic salt where the cation in neutral and the anion acts as a base with water to form hydroxide ion and conjugate acid
What is the equivalence point of a titration
Number of moles of acid = base
What is an indicator in a titration
Weak acid or base whose conjugate if a different colour. Changes colour when end point is reached
Need a conjugate acid base pair
Explain the equivalence point in a weak acid strong base titration
Moles of conjugate base = moles of strong base added
Moles of weak acid = moles of strong base added
Features of half equivalence point in weak acid strong base titration
Moles of base added = 1/2 moles of weak acid
Concentration of weak acid and its conjugate base are equal (duh)
Ph = pka of the weak acid ***
What is the buffer region
PKa +/- 1
Will consist of the weak acid and its conjugate base in a titration of weak acid with strong base
What is the buffer solution
Resists changes to ph due to addition of acid, base , or water
Basically prevents the reaction from shifting
