To prepare a sample of magnesium oxide, a small strip of magnesium ribbon was placed inside a crucible and heated strongly as shown in the diagram - Leaving Cert Chemistry - Question c - 2021
Question c
To prepare a sample of magnesium oxide, a small strip of magnesium ribbon was placed inside a crucible and heated strongly as shown in the diagram. The lid of the cr... show full transcript
Worked Solution & Example Answer:To prepare a sample of magnesium oxide, a small strip of magnesium ribbon was placed inside a crucible and heated strongly as shown in the diagram - Leaving Cert Chemistry - Question c - 2021
Step 1
Suggest a reason why the lid of the crucible was raised during the heating process.
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Answer
The lid of the crucible was raised to allow oxygen to enter and react with the magnesium. This ensures that combustion occurs effectively, as the reaction requires oxygen.
Step 2
Use the valencies of magnesium and oxygen to write the chemical formula of magnesium oxide.
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Answer
The valency of magnesium is +2 and the valency of oxygen is -2. Therefore, the chemical formula of magnesium oxide is MgO.
Step 3
Replace the words in the word equation above with chemical formulae and balance your equation.
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Answer
The word equation can be rewritten as:
ightarrow 2 ext{MgO} $$
This equation balances as there are two magnesium atoms and two oxygen atoms on both sides.
Step 4
Would you expect the mass of the crucible and its contents to increase, decrease or remain constant as the reaction proceeded? Explain your answer.
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Answer
The mass of the crucible and its contents would increase. This is because magnesium reacts with oxygen from the air to form magnesium oxide, which adds to the mass of the original magnesium ribbon.
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