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8. Calcium carbonate reacts with dilute hydrochloric acid to produce calcium chloride, water and carbon dioxide - Edexcel - GCSE Chemistry - Question 8 - 2019 - Paper 1
Question 8
8. Calcium carbonate reacts with dilute hydrochloric acid to produce calcium chloride, water and carbon dioxide. CaCO₃ + 2HCl → CaCl₂ + H₂O + CO₂ (a) A student ... show full transcript
Worked Solution & Example Answer:8. Calcium carbonate reacts with dilute hydrochloric acid to produce calcium chloride, water and carbon dioxide - Edexcel - GCSE Chemistry - Question 8 - 2019 - Paper 1
Step 1
Complete Figure 4 to show the apparatus that could be used to measure accurately the volume of gas given off in two minutes.
Answer
To measure the volume of gas produced accurately, the following apparatus should be drawn: a conical flask connected to a delivery tube, which leads to an inverted measuring cylinder or a gas syringe filled with water. Ensure the delivery tube is sealed to prevent gas escape, and there should be a bung or cork to hold everything in place.
Step 2
Explain, in terms of bond breaking and bond making, why some reactions are exothermic.
Answer
The reaction is exothermic because:
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Breaking bonds: When reacting compounds like calcium carbonate and hydrochloric acid, energy is absorbed to break the bonds in the reactants. This process is endothermic since it requires energy input.
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Making bonds: During the reaction, new bonds are formed in the products (calcium chloride, water, and carbon dioxide). The formation of these new bonds releases more energy than was initially absorbed to break the bonds in the reactants.
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Net energy change: If the energy released from bond formation is greater than the energy absorbed for bond breaking, the overall reaction releases energy to the surroundings, hence it is categorized as exothermic.