WorksheetsIonic Equilibrium
Total questions: 30
Worksheet time: 3hrs 30mins
Which of the following is a weak acid?
HF
HCl
HBr
HI
In the reaction above, the Brönsted-Lowry acids are
H2O and OH-
HSO4- and OH-
H2O and H2SO4
HSO4- and H2SO4
The solution with the lowest pH is
1.0M HBr
1.0M HCN
1.0M HCOOH
1.0M CH3COOH
Solutions of each of the hypothetical acids in the following table are prepared with an initial concentration of 0.100 M. Which of the four solutions will have the lowest pH and be most acidic?
HA
HB
HC
HD
Calculate the approximate [H3O+] concentration in a 0.220 M solution of hypochlorous acid.
Ka for HOCl = 3.0 x 10-8.
1.7 x 10-4
3.7 x 10-4
8.1 x 10-5
1.4 x 10-7
In a 0.0100 M solution of a hypothetical weak acid HW, it is found that the [H3O+] = 2.50 x 10-3 M. Ka for the acid is:
6.25 x 10-4
8.33 x 10-4
6.25 x 10-2
2.50 x 10-1
Boric acid frequently is used as an eyewash to treat eye infections. The pH of a 0.050 M solution of boric acid is 5.28. What is the Ka value of the boric acid?
5.25 × 10–6
5.51 × 10–10
5.43 × 10–8
5.33 × 10–12
A 0.100 M solution of a monoprotic weak acid has a pH of 3.00. What is the pKa of this acid?
5.00
3.00
9.99
6.00
Which of the following combinations cannot produce a buffer solution?
25cm3 0.100 moldm-3 CH3CH2COOH(aq) and 25 cm3 0.100 mol CH3CH2COONa
50cm3 0.100 moldm-3 CH3CH2COOH(aq) and 25 cm3 0.100 mol NaOH
50 cm3 0.100 moldm-3 NH3 (aq) and 50 cm3 0.100 moldm-3 HCl(aq)
50 cm3 0.100 moldm-3 NH3 (aq) and 50 cm3 0.100 moldm-3 NH4Cl(aq)
A buffer solution contains 0.36 M sodium acetate (CH3COONa) and 0.45 M acetic acid (CH3COOH), pKa = 4.8. What is the pH of this buffer solution?
4.7
5.2
3.8
6.1
Calculate the approximate [H3O+] in a solution which is 0.120 M in HF and 0.0150 M in NaF.
Ka for HF = 6.7x10-4.
8.4 x 10-5
9.0 x 10-3
0.125
5.4 x 10-3
Sodium fluoride is added to a 0.10 M HF solution. You would expect the pH to:
increase slightly
increase dramatically
decrease slightly
decrease dramatically
A buffer made by dissolving 0.43 moles of hydrofluoric acid and 0.76 moles of potassium fluoride in enough water to form 1.00 dm3 of solution. Calculate the approximate pH of this buffer solution. Ka for HF is 6.7x10-4.
1.54
2.93
3.17
3.40
A buffer is made by dissolving hydrofluoric acid and potassium fluoride in enough water. When HCl is added to the original buffer solution, the pH slightly _____, the concentration of HF _____, and the concentration of F- _____.
A
B
C
D
The Ka of HCHO2 is 1.80 x 10-4 . An aqueous buffer solution is made up of HCHO2 and NaCHO2. If we want to make a buffer solution with a pH of 4.00, the [CHO2-] / [HCHO2] ratio would have to be......
1.8 / 1
1 / 1.8
4.00 / 1
1 / 4.00
Which one of the following combinations does the titration curve represent?
Addition of a strong base to a weak acid
Addition of a weak base to a strong acid
Addition of a weak acid to a strong base
Addition of a strong acid to a weak base
What is the pH of the solution at the equivalence point?
11.3
10.0
9.3
5.3
Which one of the following indicators would be most suitable for this titration?
phenolphthalein (pKa = 9.6)
cresol red (pKa = 8.3)
methyl red (pKa = 5.1)
methyl yellow (pKa = 3.1)
Methyl orange, bromothymol blue and phenolphthalein cahnge color according to the pH shown above. The three indicators are mixed to from a solution. What is the pH range when the solution turns yellow?
0 - 14
3 - 4.5
3 - 7.5
4.5 - 6
Two different bases were titrated using HCl and the titration curves were plotted. Based on two curves shown, choose one indicator that is suitable for both titrations.
Thymol blue ( pH range = 1.2 - 2.8)
Methyl red ( pH range = 4.4 - 6.2)
Phenol red ( pH range = 6.8 - 8.4)
Bromothymol blue ( pH range = 6.0 - 7.6)
A student evaporated 200.0cm3 of a saturated solution of SrCrO4 to dryness. The residue contained 1.2×10-3 mol SrCrO4 . The solubility of SrCrO4 is:
1. 4 × 10-6 moldm-3
3. 6 × 10-5 moldm-3
2. 4 ×10-4 moldm-3
6.0 ×10-3 moldm-3
The relationship between the solubility of iron (II) hydroxide and its Ksp is
In a saturated solution of Zn(OH)2, the [Zn2+] = 1.8 x 10-5 moldm-3. Calculate the Ksp for Zn(OH)2
5.8 x 10-15
2.3 x 10-14
1.8 x 10-14
6.5 x 10-10
The solubility of barium fluoride is 3.6 × 10 -3 moldm-3. The solubility product constant is:
4.7 ×10 –8
1. 9 × 10-7
1. 3 × 10-5
2.6 ×10-5
In an experiment, a student mixes equal volumes of 0.0020 moldm-3 Pb2+ ions with 0.0040 moldm-3 I– ions. The
ion product Q is
4.0 × 10-9
3.2 × 10-8
1.3 × 10-7
8.0 × 10-6
Ksp for PbCl2 is 1.7 x 10-5. When equal volumes of 2.0 moldm-3 Pb(NO3)2 and 2.0 moldm-3 KCl are mixed,
a precipitate forms because ion product Q < K sp
a precipitate forms because ion product Q > K sp
a precipitate does not form because ion product Q < K sp
a precipitate does not form because ion product Q > K sp
When considering partition coefficients which of the following statements is FALSE?
Partition coefficient is the ratio of concentration of a solute in two immiscible layers at equilibrium.
The dissolved chemical has the same molecular structure in both solvents.
Partition coefficient does not change when the temperature changes.
The solubility of the solute in each solvent are different.
A solution of 5.00 g of an organic compound X in 50 cm3 of water was shaken with 100 cm3 of ether. After separation, the aqueous solution was found to contain 0.80 g of X. Determine the partition coefficient of x between ether and water. Give your answer to two decimal places.
(a)
When 100 cm3 of an aqueous solution containing 2.0 g of organic dye X was shaken with 20 cm3 of hexane, it was found that 1.6 g of the dye had been extracted into the hexane. Calculate the volume of hexane needed (2nd extraction) to further reduce the amount of X in the aqueous layer to less than 0.1 g.
(a)
The partition coefficient for the distribution of cyclohexanone between water and octanol is 24. Calculate the mass of cyclohexanone that would be extracted if
20cm3 of octanol was shaken with 100cm3 of an aqueous solution containing 2.5g of cyclohexanone. Give your answer to 2 sf.
(a)
