This question is about metals and metal compounds - AQA - GCSE Chemistry - Question 2 - 2018 - Paper 1

The number of protons in an atom of iron is 26.

The number of neutrons in an atom of iron is 30.

The number of electrons in an atom of iron is 26.

1. Iron has a higher melting and boiling point than sodium, making it more suitable for structural applications.
2. Iron is stronger and denser compared to sodium, which is softer and lighter.

Carbon can be used to extract nickel from nickel oxide because it is more reactive than nickel. During the reduction process, carbon displaces nickel from nickel oxide by removing oxygen, thereby allowing the nickel to be recovered.

To calculate the percentage atom economy:

1. Determine the total molar mass of the reactants:
   Molar mass of NiO = 75 g/mol + Molar mass of C = 12 g/mol = 87 g/mol.

2. The molar mass of the desired product (nickel) is 59 g/mol.

3. Apply the atom economy formula:

   $ext{Percentage Atom Economy} = \left( \frac{\text{Molar mass of desired product}}{\text{Total molar mass of reactants}} \right) \times 100$

   $= \left( \frac{59}{87} \right) \times 100 \approx 67.68\%$

Thus, the percentage atom economy is approximately 67.7% when rounded to three significant figures.