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Metal oxides are produced when metals are heated in air - AQA - GCSE Chemistry Combined Science - Question 6 - 2021 - Paper 1
Question 6
Metal oxides are produced when metals are heated in air. A student investigated the change in mass when 0.12 g of magnesium was heated in air. Figure 5 shows the a... show full transcript
Worked Solution & Example Answer:Metal oxides are produced when metals are heated in air - AQA - GCSE Chemistry Combined Science - Question 6 - 2021 - Paper 1
Step 1
0.12 g of magnesium reacted to produce 0.20 g of magnesium oxide. Calculate the number of moles of oxygen gas (O₂) that reacted.
Answer
To find the mass of oxygen that reacted, we first subtract the mass of magnesium from the mass of magnesium oxide:
Next, we calculate the number of moles of oxygen gas using its relative atomic mass:
ext{Moles of oxygen (O}_2 ext{)} = rac{ ext{Mass of oxygen}}{ ext{Relative atomic mass of O}_2} = rac{0.08 ext{ g}}{32} = 0.0025 ext{ moles}Step 2
The student repeated the experiment without a lid on the crucible. Suggest why the mass of magnesium oxide produced would be different without a lid on the crucible.
Answer
Without a lid on the crucible, magnesium oxide can escape during the reaction. This would result in a lower mass of magnesium oxide being produced because some of the product is lost to the environment.
Step 3
63.5 g of copper produces 79.5 g of copper oxide. Calculate the mass of copper oxide produced when 0.50 g of copper reacts with oxygen.
Answer
We start by establishing a ratio from the given data:
ext{Mass of copper oxide} = rac{79.5 ext{ g}}{63.5 ext{ g}} imes 0.50 ext{ g} = 0.6259 ext{ g}Rounding this to three significant figures gives:
Step 4
0.015 moles of iron reacts with 0.010 moles of oxygen (O₂). Determine the formula of the iron oxide produced and the balanced symbol equation for the reaction.
Answer
The reaction of iron with oxygen to form iron oxide can be framed as follows:
- From the mole ratio of iron to oxygen: