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5 (a) Sulfur dioxide combines with oxygen to form sulfur trioxide in an exothermic reaction - Edexcel - GCSE Chemistry - Question 5 - 2017 - Paper 1
Question 5
5 (a) Sulfur dioxide combines with oxygen to form sulfur trioxide in an exothermic reaction. 2SO₂(g) + O₂(g) ⇌ 2SO₃(g) The reaction can reach equilibrium. At 2 at... show full transcript
Worked Solution & Example Answer:5 (a) Sulfur dioxide combines with oxygen to form sulfur trioxide in an exothermic reaction - Edexcel - GCSE Chemistry - Question 5 - 2017 - Paper 1
Step 1
When a temperature higher than 450 °C is used, the equilibrium yield of sulfur trioxide decreases.
Answer
In an exothermic reaction, increasing the temperature shifts the equilibrium position to favor the endothermic direction, which is the reverse reaction in this case. According to Le Chatelier's Principle, if the temperature of an exothermic reaction is raised, the system compensates by reducing the yield of the product, sulfur trioxide (SO₃), to re-establish equilibrium. Thus, the equilibrium yield of sulfur trioxide decreases.
Step 2
Describe how the apparatus below can be used to obtain these results, showing how the results can be used to find the volume occupied by one mole of hydrogen gas, H₂, at room temperature and pressure.
Answer
To obtain the results, the following steps can be followed:
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Setup of Apparatus: Connect the magnesium ribbon to a stopcock at the top of the flask. Add excess dilute sulfuric acid to the flask.
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Conduct Reaction: When the magnesium ribbon is placed inside the acid, it will react to produce hydrogen gas. The generated hydrogen will be collected in the attached graduated gas jar.
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Measure Volume: As the reaction proceeds, monitor the volume of hydrogen gas collected in the gas jar. In this experiment, 48 cm³ of hydrogen is produced.
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Relate to Moles: To find the volume occupied by one mole of hydrogen gas, use the ideal gas law and the known conditions of temperature and pressure (room temperature and pressure are typically 20 °C and 1 atm). Under these conditions, 1 mole of gas occupies approximately 24 dm³.
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Calculate: You can calculate the number of moles of hydrogen using the equation:
ightarrow n = rac{48 ext{ cm}^3}{24000 ext{ cm}^3/mol} = 0.002 moles$$.
Thus, the relationship between the volume of hydrogen collected and the molar volume at room temperature and pressure can help establish the volume occupied by one mole of hydrogen.