PIONEER JUNIOR COLLEGE - ASKnLearn

4
11 The graph below shows the change in pH when 0.10 mol dm -3 acid is gradually
added to 10 cm 3 of 0.20 mol dm -3 alkali.
Which of the following substances could have given these results?
alkali
acid
A Ba(OH) 2 CH 3 COOH
B Ba(OH) 2 H 2 SO 4
C NaOH CH 3 COOH
D NH 3 HCl
12 Iodide ions react with peroxodisulfate ions to form iodine and sulfate.
2I - + S 2 O 8
2-
→ I 2 + 2SO 4
2-
The reaction was found to be first order with respect to I- and S 2 O 8 2- . At temperature
T, the rate constant was determined to be 0.200 mol -1 dm 3 s -1 .
2-
What is the half life of the reaction when S 2 O 8 with an initial concentration of
0.500 mol dm -3 was made to react with I - with an initial concentration of
0.010 mol dm -3 at the same temperature?
A 3.47 s B 6.93 s C 347 s D 693 s
13 The table shows experimental results obtained for the rate of the following reaction.
2XO(g) + O 2 (g) → 2XO 2 (g)
Partial pressure of XO
(arbitrary units)
100 50 75 25
Partial pressure of O 2
(arbitrary units)
100 100 25 -
Relative rate 1.0 0.50 0.19 0.063
What is the missing value of the partial pressure of O 2 in the table?
A 12.5 B 25.2 C 50.0 D 75.0