Acids Bases Qs
Acids and Bases
Q1.This question is about several Brønsted–Lowry acids and bases.
(a) Define the term Brønsted–Lowry acid.
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........................................................................................................................ (1)
(b) Three equilibria are shown below. For each reaction, indicate whether the substance immediately above the box is acting as a Brønsted–Lowry acid (A) or a Brønsted–Lowry base (B) by writing A or B in each of the six boxes. (i)
CH3COOH
+
H2O
CH3COO–
+
H3O+
(ii)
CH3NH2
+
H2O
CH3NH3+
+
OH–
(iii) HNO3
+
H2SO4
H2NO3+
+
HSO4 –
(3)
(c) A 25.0 cm3 sample of 0.0850 mol dm–3 hydrochloric acid was placed in a beaker. Distilled water was added until the pH of the solution was 1.25.
Calculate the total volume of the solution formed. State the units.
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(d) At 298 K, the value of the acid dissociation constant (Ka) for the weak acid HX in aqueous solution is 3.01 × 10–5 mol dm–3.
(i) Calculate the value of pKa for HX at this temperature.
Give your answer to 2 decimal places.
...............................................................................................................
............................................................................................................... (1)
(ii) Write an expression for the acid dissociation constant (Ka) for the
Q1.This question is about several Brønsted–Lowry acids and bases.
(a) Define the term Brønsted–Lowry acid.
........................................................................................................................
........................................................................................................................ (1)
(b) Three equilibria are shown below. For each reaction, indicate whether the substance immediately above the box is acting as a Brønsted–Lowry acid (A) or a Brønsted–Lowry base (B) by writing A or B in each of the six boxes. (i)
CH3COOH
+
H2O
CH3COO–
+
H3O+
(ii)
CH3NH2
+
H2O
CH3NH3+
+
OH–
(iii) HNO3
+
H2SO4
H2NO3+
+
HSO4 –
(3)
(c) A 25.0 cm3 sample of 0.0850 mol dm–3 hydrochloric acid was placed in a beaker. Distilled water was added until the pH of the solution was 1.25.
Calculate the total volume of the solution formed. State the units.
........................................................................................................................
........................................................................................................................
........................................................................................................................
........................................................................................................................ (3)
(d) At 298 K, the value of the acid dissociation constant (Ka) for the weak acid HX in aqueous solution is 3.01 × 10–5 mol dm–3.
(i) Calculate the value of pKa for HX at this temperature.
Give your answer to 2 decimal places.
...............................................................................................................
............................................................................................................... (1)
(ii) Write an expression for the acid dissociation constant (Ka) for the