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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. ... 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
Explain why the equilibrium yield of sulfur trioxide decreases.
Answer
The equilibrium yield of sulfur trioxide decreases when the temperature is increased because the reaction is exothermic. According to Le Chatelier's principle, increasing the temperature shifts the equilibrium position to favor the endothermic direction of the reaction to absorb the added heat. As a result, the formation of sulfur trioxide (SO₃) is reduced, leading to a lower equilibrium yield.
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 measure the volume of hydrogen gas produced, the magnesium ribbon is placed in excess dilute sulfuric acid in the flask shown. As the reaction proceeds, hydrogen gas is released and collects in the inverted graduated cylinder. By measuring the volume of gas collected at room temperature and pressure using the markings on the graduated cylinder, one can determine the volume of hydrogen gas produced from the reaction.
To find the volume occupied by one mole of hydrogen gas (H₂) at room temperature and pressure, the volumes collected from the reactions can be analyzed. For example, if 0.048 grams of magnesium produced 48 cm³ of hydrogen, you can scale up using the molar mass of magnesium to find that for every mole of hydrogen produced, under the same conditions, it would occupy approximately 24,000 cm³ or 24 liters according to Avogadro's law.