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6 (a) In some chemical reactions, bonds are broken in the reactant molecules and new bonds are formed to make the product molecules - Edexcel - GCSE Chemistry Combined Science - Question 6 - 2022 - Paper 1
Question 6
6 (a) In some chemical reactions, bonds are broken in the reactant molecules and new bonds are formed to make the product molecules. (i) Which row is correct about ... show full transcript
Worked Solution & Example Answer:6 (a) In some chemical reactions, bonds are broken in the reactant molecules and new bonds are formed to make the product molecules - Edexcel - GCSE Chemistry Combined Science - Question 6 - 2022 - Paper 1
Step 1
6 (a) (i) Which row is correct about the energy changes for these processes?
Answer
The correct answer is C: breaking a bond requires energy (energy is absorbed) while making a bond releases energy (energy is released). This reflects the nature of chemical bonds, where energy is needed to break bonds and energy is released when bonds are formed.
Step 2
6 (a) (ii) Hydrogen reacts with fluorine.
Answer
To calculate the overall energy change for the reaction:
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Determine the total bond energy of the reactants:
- H−H bond: 436 kJ/mol
- F−F bond: 562 kJ/mol
- Total energy for reactants = 436 + 562 = 998 kJ/mol
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Determine the total bond energy of the products:
- 2 × H−F bond: 2 × 158 = 316 kJ/mol
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Calculate the overall energy change:
- Energy change = Total energy of reactants − Total energy of products
- Energy change = 998 kJ/mol − 316 kJ/mol = 682 kJ/mol.
Thus, the reaction is exothermic since energy is released.