Sodium thiosulfate, Na2S2O3, can be used to investigate the effect of reaction conditions on the rate of reaction - Scottish Highers Chemistry - Question 1 - 2019
Question 1
Sodium thiosulfate, Na2S2O3, can be used to investigate the effect of reaction conditions on the rate of reaction.
(a) Sodium thiosulfate solution reacts with hydro... show full transcript
Worked Solution & Example Answer:Sodium thiosulfate, Na2S2O3, can be used to investigate the effect of reaction conditions on the rate of reaction - Scottish Highers Chemistry - Question 1 - 2019
Step 1
(i) The equation for the reaction is
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Answer
The balanced equation for the reaction between sodium thiosulfate and hydrochloric acid is:
(A) Complete the table to show the volumes of water that would have been used to vary the concentration of sodium thiosulfate.
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Experiment
Volume of 0.15 mol l⁻¹ Na2S2O3 (cm³)
Volume of water (cm³)
A
50
0
B
40
10
C
30
20
D
20
30
E
10
40
Step 3
(B) Calculate the time, in seconds, for the cross to disappear in experiment C.
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Answer
To calculate the time for the cross to disappear, we use the given rate for experiment C, which is 0.0285 s⁻¹. The time is the inverse of the rate:
Time=Rate1=0.02851≈35.09 seconds
Step 4
(iii) Use the graph to determine the temperature rise, in °C, required to double the rate of the reaction.
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From the graph, it can be observed that the rate doubles from approximately 0.04 s⁻¹ to 0.08 s⁻¹ at a temperature rise from about 20°C to 40°C. Hence, the required temperature rise is 20°C.
Step 5
(b) State two conditions necessary for the collisions to result in the formation of products.
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Particles must have sufficient or enough energy to react.
Particles must have the correct orientation during collisions.
Step 6
(c) (i) Draw an X on the potential energy diagram to show where the activated complex is formed.
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The X should be drawn at the peak of the curve on the potential energy diagram, indicating where the activated complex is formed.
Step 7
(c) (ii) Add a dotted line to the diagram to show the change in potential energy with the catalyst.
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The dotted line should be drawn below the original curve to illustrate the lower activation energy when a catalyst is present.
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