A
TRUE or FALSE
A buffer consists of a strong acid and weak base
FALSE
Weak base and conjugate acid
or
Weak acid and conjugate base
TRUE or FALSE
Adding NaOH to a solution of NaCl will make it more soluble
FALSE
Common ion effect
What is a polyprotic acid?
Any acid with 1 or more ionizable hydrogens
A precipitate forms when....
A) Q>Ksp B) Q<Ksp C) Q=Ksp
A
What is the solubility of Zn(OH)2 in a solution that is pH=7? (ksp=4.5e-17)
x=s=2.2e-6 M
Zn(OH)2 ⇔ Zn + 2OH
I 0 0
C +x +2x
E x 2x
[Zn][OH]2 = (x)(2x)2 = 4x3
ksp=4x3 = 2.2e-6 M
Which of these is the most soluble
A) Ksp(CuCO3)=1.4×10-10
B) Ksp(MgCO3)=3.5×10-8
C) Ksp(Zn3(PO4)2=9.0×10-33
B
Higher Ksp = More Soluble
You need to prepare a buffer with pH = 5.00. The conjugate acid-base pairs you have available are
A) HClO/NaClO (Ka, HClO = 2.9 x 10-8)
B) HCHO2/NaCHO2 (Ka, HCHO2 = 1.8 x 10-4)
C) HC2H3O2/NaC2H3O2 (Ka, HC2H3O2 = 1.8 x 10-5 )
Which of the acid-base pairs should you use to make your buffer?
C
pka=-log(1.8 x 10-5 ) = 4.74
Within range of buffer capacity if pH = 5
What is pH of a titration of 25mL of 0.1M HCl and 0.1M NaOH when no base is added?
pH = 1
strong acid -> plug directly into pH=-log[H]
pH = -log(0.1M)
Calculate titration of 100mL of 0.1M NH3 titrated w 50mL added of 0.1M HCl (kb=1.8e-5)
pH = 9.26
Moles
NH3 = 0.1*0.1L =0.010mol
H3O = 0.1*0.05L = 0.005mol
pH=pka
Find ka with kb
pH=-log(ka)
Determine if AgI(s) is more soluble in acid solution than neutral solution (when acid is added)
Strong acid forms in products so it is not soluble in acid
AgI + H3O+ <=> HI + H2O + Ag+
(If a SA or SB forms in products, it prevents the precipitate rxn from occurring)