Ionic Equilibria, pH and Buffers Flashcards
What is an electrolyte solution?
A solution that has ions present and can conduct electricity
Can you easily measure the equilibrium constant of a strong electrolyte? Why?
No. Ions are almost completely dissociated
What is the calculation for equilibrium constant?
K = [C][D]/[A][B]
If the equilibrium of a solution lies to the RHS, what is the value of K?
> 1
If the equilibrium of a solution lies to the LHS, what is the value of K
< 1
What is the value of Kw?
1 x 10^-14
What type of solution has a [H+] of less than 1 x 10^-7?
Acidic
What type of solution has a [H+] of more than 1 x 10 -7?
Alkaline
Give the equation for pH? (2 possible answers)
pH = -log10[H+]
OR
pH = log10(1/[H+])
T or F? If you have a higher [H+], you have a higher pH
False
What can limit the activity of H+? What is this ability called?
Presence of other ions.
Ionic strength
What is the equation relating to H+ activity?
pH = -log {[H+ x [f]}
How does a pH sensor take a measurement?
Determines the potential difference between measuring electrode and reference electrode
What type of solution will give a positive potential difference
Acidic
What type of solution will give a negative potential difference?
Basic
What two buffers would you use to calibrate a basic solution?
pH 7 and pH 10
What is the relationship between Ka/b and strength of acid/base
The larger the Ka/b , the stronger the acid/base
What is the difference between a strong and weak acid?
A strong acid is fully ionised whereas a weak acid is not
What is the relationship between pH and pKa for an acid?
pH = 0.5 pKa - 0.5 log c
What is the relationship between pH and pKb
pH = 0.5 (pKw + pKa + log c)
Give some characteristics of salts
Ionic H2O soluble High melting point Crytalline solids Can increase the H2O solubility of a drug
What type of salt is produced by a reaction between a strong acid and a strong base?
Neutral salt
Give an example of a strong acid/strong base reaction and explain why the salt is acidic, basic or neutral
HCl + NaOH -> NaCl + H2O
NaCl dissociates into Na+ and Cl-. Neither of these ions react with water so salt is neutral
What type of salt is produced by a strong acid/weak base reaction
Acidic Salt