When chromium reacts with oxygen, chromium oxide is formed - Edexcel - GCSE Chemistry Combined Science - Question 2 - 2021 - Paper 1
Question 2
When chromium reacts with oxygen, chromium oxide is formed.
(a) (i) Write the word equation for this reaction.
(ii) What type of reaction occurs when chromium reac... show full transcript
Worked Solution & Example Answer:When chromium reacts with oxygen, chromium oxide is formed - Edexcel - GCSE Chemistry Combined Science - Question 2 - 2021 - Paper 1
Step 1
Write the word equation for this reaction.
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Answer
Chromium + Oxygen → Chromium Oxide
Step 2
What type of reaction occurs when chromium reacts with oxygen?
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Answer
D. oxidation
Step 3
Calculate the relative formula mass of chromium oxide, Cr₂O₃.
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Answer
To calculate the relative formula mass of Cr₂O₃, we add the relative atomic masses of its constituent elements:
Chromium (Cr): 2 × 52 = 104
Oxygen (O): 3 × 16 = 48
Thus, the total relative formula mass is:
104+48=152
Step 4
Place the metals in order of reactivity from most to least reactive.
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Most reactive: Magnesium
Least reactive: Silver
Step 5
What is the safest way to ignite the gas?
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Answer
C. put a lighted splint at the open end of the test tube
Step 6
State the observation made in this test that shows that the gas is hydrogen.
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Answer
The gas ignites with a 'pop' sound when a lighted splint is introduced.
Step 7
State why iron can be extracted by heating iron oxide with carbon.
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Iron can be extracted because carbon can reduce iron oxide to iron by displacing it from the oxide.
Step 8
State why electrolysis is not used to extract iron.
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Electrolysis is not used to extract iron because it is a costly method compared to reduction with carbon.
