Photo AI
This question is about the reaction between hydrogen sulfide (H₂S) and oxygen - AQA - GCSE Chemistry - Question 8 - 2021 - Paper 1
Question 8
This question is about the reaction between hydrogen sulfide (H₂S) and oxygen. The equation for the reaction is: 2 H₂S(g) + 3 O₂(g) → 2 H₂O(g) + 2 SO₂(g) What doe... show full transcript
Worked Solution & Example Answer:This question is about the reaction between hydrogen sulfide (H₂S) and oxygen - AQA - GCSE Chemistry - Question 8 - 2021 - Paper 1
Step 1
Step 2
Calculate the volume of oxygen required to react with 50 cm³ of hydrogen sulfide.
Answer
From the balanced equation, 2 moles of H₂S react with 3 moles of O₂. Therefore, the ratio of H₂S to O₂ is 2:3. To find the volume of oxygen required for 50 cm³ of H₂S:
-
Use the ratio:
50 cm³ H₂S × (3 O₂ / 2 H₂S) = 75 cm³ O₂
Therefore, the volume of oxygen required is 75 cm³.
Step 3
Complete Figure 6.
Answer
-
Draw the profile line starting from the reactants' energy level, reaching an energy peak, and then dropping to the products' energy level showing a net loss in energy (exothermic).
-
Label the peak of the curve as the 'Activation energy'.
-
Draw a horizontal line from the initial reactants level to the final product level and label this line as 'Overall energy change'.
Step 4
Calculate the bond energy X for the S=O bond.
Answer
To find the bond energy X for the S=O bond:
-
Total energy for bonds broken:
- (4 × 364) + (3 × 498) = 2950 kJ/mol
-
Total energy for bonds formed:
- (2 × 464) + (2 × X) = 2 × 464 + 2X
-
According to the information provided, the energy released forming new bonds is 1034 kJ/mol greater than the energy needed to break existing bonds:
2950 + 1034 = 1865 + 4X
3984 = 1865 + 4X
3984 - 1865 = 4X
2121 = 4X
X = 532 kJ/mol
Therefore, the bond energy X for the S=O bond is 532 kJ/mol.