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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 exc... 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
Based on the observations:
- Metal Z produced bubbles rapidly and had no metal remaining, indicating it is highly reactive.
- Metal Y also produced bubbles quickly and completely reacted after three minutes, making it more reactive than W and X.
- Metal W formed bubbles quickly, but some metal remained, suggesting less reactivity than Y and Z.
- Metal X had very few bubbles and remained largely unchanged, indicating it is the least reactive.
Thus, the order of reactivity from least 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 dilute sulfuric acid eventually stopped despite the presence of solid metal Y due to the formation of a barrier layer of metal sulfate on its surface. This layer prevents further reaction between the metal and sulfuric acid, as it serves as a physical barrier that limits access of acid to the metal surface. As the concentration of H⁺ ions in the solution decreases, the reaction conditions also become less favorable, contributing to the cessation of the reaction.