Sodium thiosulfate reacts with dilute hydrochloric acid as shown - AQA - A-Level Chemistry - Question 1 - 2019 - Paper 3
Question 1
Sodium thiosulfate reacts with dilute hydrochloric acid as shown.
Na2S2O3(aq) + 2HCl(aq) → 2NaCl(aq) + SO2(g) + S(s) + H2O(l)
1. Give the simplest ionic equation f... show full transcript
Worked Solution & Example Answer:Sodium thiosulfate reacts with dilute hydrochloric acid as shown - AQA - A-Level Chemistry - Question 1 - 2019 - Paper 3
Step 1
1. Give the simplest ionic equation for this reaction.
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Answer
The simplest ionic equation for the reaction is:
ightarrow ext{SO}_2 (g) + ext{S} (s) + ext{H}_2 ext{O} (l)$$
Step 2
2. State the property of SO2 that causes pollution when it enters rivers.
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Answer
SO2 is acidic in nature, which means it can produce H+ ions in solution. This property contributes to the acidification of water bodies, adversely affecting aquatic life.
Step 3
Give an equation to show the reaction of SO2 with water.
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Answer
The reaction of SO2 with water can be represented as follows:
ightarrow ext{H}_2 ext{SO}_3 (aq)$$
Step 4
3. Draw a diagram to show the shape of a molecule of H2O.
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Answer
The shape of a water molecule (H2O) is bent and can be depicted as follows:
H
|
O—H
This diagram includes lone pairs of electrons on the oxygen atom.
Step 5
State the H–O–H bond angle.
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Answer
The H–O–H bond angle in a water molecule is approximately 104.5°.
Step 6
Explain this shape and bond angle.
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The bent shape of the water molecule is due to the two lone pairs of electrons on the oxygen atom, which repel the hydrogen atoms. This repulsion causes the bond angle to be less than the ideal tetrahedral angle of 109.5°.
Step 7
4. Describe an experiment to investigate the effect of temperature on the initial rate of this reaction.
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Answer
To investigate the effect of temperature on the reaction rate:
Outline of Method: Set up a reaction between sodium thiosulfate and hydrochloric acid in a conical flask placed on a white tile. Measure the time taken for a fixed amount of sulfur (
S) to be produced.
Measuring Time: Use a stopwatch to time how long it takes for the solution to turn opaque (the fixed amount of sulfur) as a result of the reaction.
Presenting Results: Record the times at different temperatures. Create a table to show temperature vs. reaction time, and plot a graph of temperature (x-axis) against the rate of reaction (y-axis).
Expected Graph Sketch: The graph is expected to show an increase in the rate of reaction with increasing temperature, indicating that a higher temperature accelerates the reaction.
