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A student carried out an investigation to determine the order of reactivity of four metals, W, X, Y and Z - Edexcel - GCSE Chemistry Combined Science - Question 6 - 2022 - Paper 1
Question 6
A student carried out an investigation to determine the order of reactivity of four metals, W, X, Y and Z. A piece of metal W was added to a test tube containing ex... show full transcript
Worked Solution & Example Answer:A student carried out an investigation to determine the order of reactivity of four metals, W, X, Y and Z - Edexcel - GCSE Chemistry Combined Science - Question 6 - 2022 - Paper 1
Step 1
Use the information in Figure 6 to place the metals in order of reactivity from the least reactive to the most reactive.
Answer
From the observations made in Figure 6:
- Metal Z reacted the fastest, as it produced bubbles very quickly with no metal remaining, indicating it is the most reactive.
- Metal Y reacted quickly, with all metal consumed after three minutes, placing it next in order of reactivity.
- Metal W showed bubbles quickly but had some metal remaining, making it less reactive than Y but more than X.
- Metal X exhibited minimal reaction with a few bubbles and no change after three minutes, making it the least reactive. Therefore, the order from least reactive to most reactive is:
X < W < Y < Z
Step 2
Explain why the reaction between metal Y and excess dilute sulfuric acid stopped even though there was solid metal Y left.
Answer
The reaction between metal Y and excess dilute sulfuric acid ceases because:
- The reaction rate decreases as the concentration of hydrogen ions (H⁺) around the surface of the metal Y diminishes as the reaction proceeds and reacts with the metal, reducing active sites for further reaction.
- As metal Y reacts, it forms a layer of metal sulfate on its surface, which can act as a barrier preventing further contact between the acid and the remaining solid metal, effectively hindering the reaction.
- As the solution becomes saturated with products, the effective concentration of H⁺ ions in the vicinity of the solid metal decreases, leading to a slowdown until the reaction stalls.