The reactivity of copper, magnesium and zinc was investigated - Edexcel - GCSE Chemistry Combined Science - Question 3 - 2019 - Paper 1
Question 3
The reactivity of copper, magnesium and zinc was investigated.
Each metal was placed separately in dilute hydrochloric acid.
The amount of effervescence was observed... show full transcript
Worked Solution & Example Answer:The reactivity of copper, magnesium and zinc was investigated - Edexcel - GCSE Chemistry Combined Science - Question 3 - 2019 - Paper 1
Step 1
(i) Which piece of apparatus should be used to find the mass of metal used?
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Answer
The correct piece of apparatus to find the mass of metal used is a balance. This device accurately measures the mass of solid materials, making it ideal for this experiment.
Step 2
(ii) State two variables, apart from the mass of the metals, that should be controlled in this investigation.
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Answer
The concentration of the hydrochloric acid should be kept constant to ensure that variations in reaction rates are due to the metals themselves.
The surface area of the metals should be controlled, meaning they should be in the same form (e.g., all powdered or all in large chunks) to ensure comparable results.
Step 3
(iii) Give the reason why copper does not produce any effervescence.
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Answer
Copper does not produce any effervescence because it is less reactive than hydrogen. Hence, when copper is placed in dilute hydrochloric acid, it does not displace hydrogen ions from the acid.
Step 4
(iv) Fill in the missing state symbols in the spaces provided.
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Answer
The correct state symbols are:
Mg(s) + 2HCl(aq) → MgCl₂(aq) + H₂(g)
Thus, the completed equation shows that magnesium chloride is in aqueous solution and hydrogen gas is produced.
Step 5
(i) Write the formula of potassium sulfate.
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The formula of potassium sulfate is K₂SO₄.
Step 6
(ii) Calculate the mean mass of potassium sulfate obtained, giving your answer to two decimal places.
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Answer
To calculate the mean mass of potassium sulfate:
Mean mass = ( rac{5.22 + 5.24 + 5.21}{3}) = ( rac{15.67}{3}) = 5.23 g.
Thus, the mean mass of potassium sulfate obtained is 5.23 g.
