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.
(i) Write the word equation for this reaction.
(ii) What type of reaction occurs when chromium reacts w... 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
The word equation for the reaction of chromium with oxygen is:
Chromium + Oxygen → Chromium Oxide
Step 2
What type of reaction occurs when chromium reacts with oxygen?
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Answer
The correct option is D. oxidation. This is because in this reaction, chromium gains oxygen.
Step 3
Calculate the relative formula mass of chromium oxide, Cr2O3.
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Answer
To calculate the relative formula mass of Cr2O3, use the atomic masses given:
Chromium (Cr) = 52 (relative atomic mass)
Oxygen (O) = 16 (relative atomic mass)
The formula mass is calculated as:
extRelativeFormulaMass=2imes52+3imes16=104+48=152
Thus, the relative formula mass of Cr2O3 is 152.
Step 4
Place the metals in order of reactivity from most to least reactive.
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Answer
Based on the observations:
Magnesium (steady bubbling, highly reactive)
Iron (very slow bubbling, less reactive than magnesium)
Silver (no change, least reactive)
Most reactive: MagnesiumLeast reactive: Silver
Step 5
What is the safest way to ignite the gas?
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Answer
The safest method to ignite the hydrogen gas is C. put a lighted splint at the open end of the test tube. This allows for a controlled ignition.
Step 6
State the observation made in this test that shows that the gas is hydrogen.
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Answer
The observation that indicates the gas is hydrogen is a 'pop' sound when the lighted splint is introduced into the test tube.
Step 7
State why iron can be extracted by heating iron oxide with carbon.
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Iron can be extracted by heating iron oxide with carbon because carbon acts as a reducing agent, which removes oxygen from the iron oxide, producing iron.
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 an expensive process compared to reduction with carbon, which is more economical for large-scale iron production.
