The ionisation constant of an acid, Ka , is the measure of the strength of an acid. The Ka values of acetic acid, hypochlorous acid and formic acid are and , respectively. The correct order of pH value of 0.1 mol dm-3 solutions of these acids is -
1. Acetic acid > hypochlorous acid > formic acid
2. Hypochlorous acid < acetic acid > formic acid
3. Formic acid > hypochlorous acid > acetic acid
4. Formic acid < acetic acid < hypochlorous acid
are the respective ionisation constants for the following reactions.
\(\mathrm{H}_2 \mathrm{~S} \rightleftharpoons \mathrm{H}^{+}+\mathrm{HS}^{-}\)
\(\mathrm{HS}^{-} \rightleftharpoons \mathrm{H}^{+}+\mathrm{S}^{2-}\)
\(\mathrm{H}_2 \mathrm{~S} \rightleftharpoons 2 \mathrm{H}^{+}+\mathrm{S}^{2-}\)
The correct relationship between is:
1. | \(\mathrm{K}_{\mathrm{a}_3}=\mathrm{K}_{\mathrm{a}_1} \times \mathrm{K}_{\mathrm{a}_2} \) | 2. | \(\mathrm{K}_{\mathrm{a}_3}=\mathrm{K}_{\mathrm{a}_1}+\mathrm{K}_{\mathrm{a}_2} \) |
3. | \(K_{a_3}=K_{a_1}-K_{a_2} \) | 4. | \(\mathrm{K}_{\mathrm{a}_3}=\mathrm{K}_{\mathrm{a}_1} / \mathrm{K}_{\mathrm{a}_2}\) |
The concentration of hydrogen ion in a sample of soft drink is . The pH of the soft drink will be:
1. 3.14
2. 2.42
3. 11.58
4. 6.00
0.561 g of KOH is dissolved in water to give 200 mL of solution at 298 K. The pH of the solution will be
1. | 12.70 | 2. | 1.30 |
3. | 3.14 | 4. | 11.70 |
The ionization constant of chloroacetic acid is 1.35 × 10–3. The pH of a 0.1 M acid solution will be:
1. | 1.94
|
2. | 6.14
|
3. | 3.23
|
4. | 5.64 |
PCl5, PCl3, and Cl2 are at equilibrium at 500 K in a closed container and their concentrations are 0.8×10-3 mol L-1 , 1.2×10-3 mol L-1 and 1.2×10-3 mol L-1, respectively.
The value of Kc for the reaction PCl5(g) ⇌ PCl3(g) + Cl2(g) will be:
1. | 1.8 × 103 mol L-1 | 2. | 1.8 × 103 |
3. | 1.8 × 10-3 mol L-1 | 4. | 0 . 55 × 104 |
Given below are two statements:
Assertion (A): | A solution containing a mixture of acetic acid and sodium acetate maintains a constant value of pH on the addition of small amounts of acid or alkali. |
Reason (R): | A solution containing a mixture of acetic acid and sodium acetate acts as a buffer solution. |
1. | Both (A) and (R) are true and (R) is the correct explanation of (A). |
2. | Both (A) and (R) are true but (R) is not the correct explanation of (A). |
3. | (A) is true but (R) is false. |
4. | (A) is false but (R) is true. |
Match the following species with the corresponding conjugate acid.
Species | Conjugate acid |
A. | 1. |
B. | 2. |
C. | 3. |
D. | 4. |
5. |
Codes
A | B | C | D | |
1. | 2 | 5 | 1 | 5 |
2. | 2 | 4 | 3 | 5 |
3. | 5 | 4 | 3 | 2 |
4. | 4 | 5 | 3 | 2 |
Match the standard free energy of the reaction with the corresponding equilibrium constant.
A. | 1. K>1 |
B. | 2. K=1 |
C. | 3. K=0 |
4. K<1 |
Codes
A | B | C | |
1. | 4 | 1 | 2 |
2. | 1 | 2 | 3 |
3. | 2 | 4 | 3 |
4. | 4 | 1 | 3 |
A sample of pure PCl5 was introduced into an evacuated vessel at 473 K.
After equilibrium was attained, a concentration of PCl5
was found to be 0.5 × 10–1 mol L–1. If the value of
Kc is 8.3 × 10–3 mol L–1, the concentrations of
PCl3 and Cl2 at equilibrium would be:
PCl5 (g) PCl3 (g) + Cl2(g)
1. | |
2. | |
3. | |
4. |