Acids and bases Flashcards
What is a bronsted acid?
proton donor
What is a bronsted base?
proton acceptor
What is the pH?
the concentration of hydrogen ions in solution
Give 7 examples of strong acids.
Nitric, Sulfuric, Chloric, Hydrochloric, Hydrobromic, Hydroiodic, Hydronium ion
Remember as NSC4Hi
Give 7 examples of weak acids.
Hydrocyanic, Hypoclorous, Hydrofluoric, Hydrogen Sulfide, Sulfurous, Phosphoric, Nitrous,
Remember as 4HSPN
What are the common strong bases?
Group 1A metal hydroxides.
What is the equation for the acid equilibrium constant?
Ka = [H+][A-] / [HA]
What is the trend with increasing dissociation constant?
The larger the dissociation constant, the stronger the acid or base.
What is the equation for the base equilibrium constant?
Kb = [HB+][OH-] / [B]
What are the components of a conjugate acid-base pair?
The acid HA and the base it produces A-
What are examples of biological conjugate acid bases?
Amino acids
Due to excessive acidity of COOH, the dominant forms are COO- and NH3+
What is a zwitterion?
A zwitterion bears no net charge which has a positive and negative ion in one compound
What is the ion product constant (Kw) at STP?
Kw = [H+] [OH-] = 1.0 x 10¹⁴
What is the pH of neutral water?
10⁻⁷M
What is the equation for pH?
-log10[H+]
What colour does litmus indicator paper?
Red for acid
Blue for base
What colour does phenolphthalein indicator turn?
Colourless for acid
Pink for base
What is the equivalence point?
The volume of titrant required to change the colour of indicator during titration.
What is the trend with strength of conjugate acids?
The weaker the conjugate acid, the stronger the conjugate base.
What is a buffer?
a solution that resists change to pH when small amounts of acid or base are added or when the solution is diluted
How do you work out pKa?
pH = pKa + log([salt]/[acid])
What is a useful biological buffer?
A combination of phosphate salts
What factor must be thought about when picking an indicator for acid-base titrations?
Must have a pKA close to that of the pH of the equivalence point.
What is the equivalence point in weak acid-strong base titrations?
Alkaline
What is the equivalence point in strong acid-weak base titrations?
Acidic
What is the equivalence point in strong acid-strong base titrations?
close to neutral pH
What is the best oxidising agent for redox titrations?
Potassium permanganate (KMnO4)
It turns colourful at the equivalence point.