QUESTION 7 (Start on a new page.)
Two beakers, A and B, contain strong bases.
Beaker A: 500 cm³ of barium hydroxide, Ba(OH)2(aq) of unknown concentration X
Beaker B: 400 cm³ of potassium hydroxide, KOH(aq) of concentration 0,1 mol dm³
7.1
7.2
7.3
Define a base according to the Arrhenius theory.
Calculate the number of moles of hydroxide ions (OH) in beaker B.
The contents of beakers A and B are added together in beaker C. The
solution in beaker C has a pH of 13.
Assume that the volumes are additive and that the temperature of the
solutions is 25 °C.
C
B
A
Ba(OH)2(aq) 500 cm³
pH = 13
0,1 mol dm³
400 cm³ KOH(aq)
7.3.1
Calculate the concentration, X, of the Ba(OH)2 in beaker A.
The solution in beaker C is titrated with ethanoic acid. It was found that
15 cm³ of the solution neutralises 30 cm³ of the acid.
The balanced equation for the reaction is:
7.3.2
7.3.3
CH3COOH(aq) + OH(aq)
-> CH, COO (aq) + H2O(l)
(2)
(2)
Is ethanoic acid, CH3COOH(aq), a WEAK acid or a STRONG acid?
Give a reason for the answer.
Calculate the concentration of the ethanoic acid.
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