Some Group 1 and Group 7 elements are very reactive - OCR Gateway - GCSE Chemistry: Combined Science - Question 14 - 2019 - Paper 10
Question 14
Some Group 1 and Group 7 elements are very reactive.
Look at the reaction cycle.
Element A
Add to water
NaOH + gas D
Heat with Br₂(l)
Compound B
Dissolve in wate... show full transcript
Worked Solution & Example Answer:Some Group 1 and Group 7 elements are very reactive - OCR Gateway - GCSE Chemistry: Combined Science - Question 14 - 2019 - Paper 10
Step 1
Identify element A.
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Element A is likely Sodium (Na) because it is a Group 1 element known for its vigorous reaction with water.
Step 2
Identify compound B.
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Compound B is formed by the reaction of Element A with water, hence it is Sodium Hydroxide (NaOH).
Step 3
Write a balanced equation for the reaction of element A with Br₂(l).
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The balanced equation for the reaction of Sodium (Na) with Bromine (Br₂) is:
ightarrow 2 ext{NaBr} (s)$$
Step 4
Identify compound C.
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Compound C is likely Sodium Chloride (NaCl) as it is formed when Compound B reacts with hydrochloric acid in the presence of Chlorine gas (Cl₂).
Step 5
Give a reason for your answer to (c)(i).
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Sodium Chloride (NaCl) is a common product when Sodium Hydroxide (NaOH) reacts with Hydrochloric Acid (HCl); thus, it is a reasonable identification for compound C.
Step 6
test for carbon dioxide
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To test for carbon dioxide, bubble the gas through limewater. If the limewater turns cloudy, carbon dioxide is present.
Step 7
result with gas D
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If gas D is carbon dioxide, the limewater will turn cloudy.
Step 8
test for hydrogen
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To test for hydrogen, introduce a lit splint to the gas. A 'pop' sound indicates the presence of hydrogen.
Step 9
result with gas D
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If gas D is hydrogen, a 'pop' sound will be heard when the lit splint is introduced.
Step 10
test for oxygen
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To test for oxygen, insert a glowing splint into the gas. If it reignites, oxygen is present.
Step 11
result with gas D
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If gas D is oxygen, the glowing splint will reignite.
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