Calculate the relative atomic mass of titanium in this sample - Edexcel - GCSE Chemistry - Question 6 - 2020 - Paper 1

To find the mass of oxygen that combines with 0.500 g of iron wool:

1. Weigh the empty crucible and its lid to get their initial mass.
2. Add the 0.500 g of iron wool to the crucible and weigh it again to get the combined mass of iron and crucible.
3. Heat the crucible gently to allow the iron to react with oxygen in the air, ensuring the lid is loosely placed to allow oxygen to enter.
4. Once the reaction is complete, allow the crucible to cool down.
5. Weigh the crucible with the iron oxide formed. Subtract the initial mass of the crucible to find the mass of iron oxide.
6. The difference in mass reflects the mass of oxygen that combined with the iron.

Given:

• Mass of iron = 2.24 g
• Mass of oxygen = 0.96 g
• Atomic mass of Fe = 56.0 g/mol
• Atomic mass of O = 16.0 g/mol

1. Calculate the number of moles of iron and oxygen:

   • Moles of Fe = \frac{2.24 ext{ g}}{56.0 ext{ g/mol}} = 0.04 ext{ mol}
   • Moles of O = \frac{0.96 ext{ g}}{16.0 ext{ g/mol}} = 0.06 ext{ mol}

2. Find the simplest mole ratio:

   • Ratio of Fe:O is:
   • Fe : O = 0.04 : 0.06 = 1 : 1.5 = 2 : 3

3. Therefore, the formula of the oxide of iron is:

   $Fe_2O_3$

4. Balanced equation for the reaction is:

   $4Fe + 3O_2 \rightarrow 2Fe_2O_3$