WorksheetspH and buffers, solubility
Total questions: 20
Worksheet time: 3600secs
What would be the result when 50 mL of distilled water are added to an ethanoic acid/ sodium ethanoate buffer?
The H+ ions in water would react with the sodium ethanoate in the buffer
None of the responses
The buffer capacity will be exceeded
The OH- ions in water would react with the ethanoic acid in the buffer.
What will be observed when the following solutions are mixed: 1 M NaCl (aq) and 1 M AgNO3 (aq)?
Effervescence will be seen
An acidic solution will be obtained
A precipitate will form
A misty gas is evolved
A saturated solution of magnesium hydroxide, Mg(OH)2 is prepared at 25°C and the hydroxide ion concentration of the solution is found to be 0.014 M. Calculate the Ksp for Mg(OH)2 at this temperature.
5.55 x 10-10 M3
2.30 x 10-8 M3
1.37 x 10-6 M3
7.61 x 10-11 M3
A sample of silver chloride, AgCl(s) is added to some distilled water and a few drops of concentrated ammonia, NH3 are then added to the mixture. Which of the following will be observed?
The amount of AgCl that dissolves in water is unaffected by the addition of ammonia
Less AgCl goes into solution after the ammonia is added
More AgCl solid dissolves after the ammonia is added
AgCl is neutralized by the ammonia
Arrange the following bases from weakest to strongest:
(CH3)2NH (pKb = 3.27); NH2OH (pKb = 8.06); NH3 (pKb = 4.75); C5H5N (pKb = 8.77)
NH3 <(CH3)2NH < NH2OH < C5H5N
C5H5N < NH2OH < (CH3)2NH < NH3
(CH3)2NH < NH3 < NH2OH < C5H5N
C5H5N < NH2OH < NH3 < (CH3)2NH
Which of the following equations is correct?
I. H2SO3 (aq) + H2O ⇌ HSO2(aq) + H3O+ (aq)
II. H2PO4- (aq) + NH3 (aq) ⇌ NH4+ (aq) + HPO42-(aq)
III. CH3CH2COOH(aq) + OH-(aq) ⇌ CH3CH2COO-(aq) + H3O+(aq)
IV. NH4+ (aq) + CN- (aq) ⇌ HCN (aq) + NH2 (aq)
I
IV
II
III
Calculate the molar solubility of calcium carbonate CaCO3 if its solubility product is 5 x 10-9
7.07 x 10-5 mol L-1
1.11 x 10-4 mol L-1
9.43 x 10-7 mol L-1
3.02 x 10-7 mol L-1
Which of the following statements are true?
I. When a base is added to a solution the pOH of that solution increases.
II. Water molecules are amphiprotic
III. The ammonium cation can produce hydrogen ions in aqueous solution
IV. Up to three protons can be produced from phosphoric acid.
II, III & IV
I, II, III & IV
II & III
I, II & IV
Which of the following indicators is most suitable for the titration between ascorbic acid (vitamin C) and sodium hydroxide.
Phenolphthalein
Bromoscresol blue
Methyl orange
Bromocreso green
What concentration of cyanide anion, CN- must be present if a buffer of pH 8.7 is to be formed with 1.7 mol dm-3 of hydrocyanic acid, HCN? The pKa of hydrocyanic acid is 9.21.
4.1 mol dm-3
0.2 mol dm-3
3.2 mol dm-3
0.53 mol dm-3
Which of the following represents the Ksp expression for iron phosphate, Fe3(PO4)2?
[Fe2+][2PO4-]2
[Fe2+]3[PO43-]2
[Fe3+]3[PO42-]
[Fe3+][2PO42-]
The pH of a 0.10 M solution of histidine, C6H9N3O2, a weak organic base was measured at equilibrium and found to be 8.33. Calculate the hydroxide ion concentration in this solution.
1.40 x 10-5 M
9.90 x 10-2 M
2.14 x 10-6 M
8.93 x 10-5 M
A solution contains anions with the following concentrations:
0.20 M CO32-and 0.01 M Cl-
If a dilute AgNO3 solution is added to this solution, which is the first compound to precipitate.
AgCl (Ksp = 1.8 x 10-10)
Ag2CO3 (Ksp = 1.2 x 10-12)
None of the responses
Both compounds will precipitate at the same time
Which of the following is true regarding a C2H5COOH/C2H5COO- buffer?
The buffer is comprised of a weak base and its conjugate
It is an acidic buffer
Aqueous ammonia can be neutralized by the anion in the buffer
A pH of 8.45 can be maintained by this buffer
Which of the following titration curves is most likely to result if a titration was done by adding sulfuric acid to aqueous ammonia?
d
a
b
c
Given that the pKa of the ammonia ion is 9.24, what is the pH of a buffer mixture composed of equal concentrations of NH4Cl and NH3?
9.24
10.80
6.56
7.50
Which of the following best defines a Lewis acid?
Any substance that can act as an electron or an electron-pair acceptor
Any substance that can donate a proton to another substance
Any substance that can act as an electron or an electron-pair donor
A substance that produces hydrogen ions in aqueous solution.
The average normal concentration of Ca2+ in urine is 5.33 g L-1. What concentration of oxalate is needed to precipitate calcium oxalate to initiate formation of a kidney stone?
CaC2O4 (s) ⇌ Ca2+ (aq) + C2O42- (aq)
Ksp of CaC2O4 = 2.3 x 10-9 Ca = 40 g
2.35 x 10-5 M
1.73 x 10-8 M
5.52 x 10-7 M
1.01 x 10-4 M
Consider the following solubility equilibrium in a saturated solution:
Ag2CO3(s) ⇌ 2Ag+(aq) + CO32-(aq)
If excess aqueous ammonia is added to the solution what will be the result?
The concentration of carbonate ions remains constant
The carbonate ions are neutralized by ammonia
The solubility equilibrium remains unchanged
The position of equilibrium shifts to the right
Which of the following is false about the reaction quotient, Q, as applied to solubility product equilibria and the solubility product constant, Ksp?
If Q < Ksp, a precipitate will form
If Q = Ksp, the system is at equilibrium
If Q < Ksp, no precipitate will form
If Q = Ksp, the solution is saturated
