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The arrangement of carbon atoms in diamond is shown - Edexcel - GCSE Chemistry - Question 6 - 2015 - Paper 1
Question 6
The arrangement of carbon atoms in diamond is shown. Explain why diamond has a very high melting point. (i) Calculate the percentage by mass of calcium in calcium ... show full transcript
Worked Solution & Example Answer:The arrangement of carbon atoms in diamond is shown - Edexcel - GCSE Chemistry - Question 6 - 2015 - Paper 1
Step 1
Explain why diamond has a very high melting point.
Answer
Diamond has a very high melting point due to its strong covalent bonding. Each carbon atom in diamond forms four strong covalent bonds with other carbon atoms, creating a three-dimensional tetrahedral lattice structure. This extensive bonding network requires a significant amount of energy to break, resulting in a high melting point.
Step 2
Calculate the percentage by mass of calcium in calcium chloride, CaCl₂.
Answer
To calculate the percentage by mass of calcium in calcium chloride, we first need to find the mass of calcium in the compound:
- Relative formula mass of CaCl₂ = 40 (Ca) + 2 × 35.5 (Cl) = 111 g/mol.
- Mass of calcium = 40 g.
Now we can find the percentage:
Percentage by mass of Ca = ( \frac{40}{111} \times 100 \approx 36.04 % )
Step 3
Which row of the table correctly shows the solubility of calcium chloride and barium sulfate in water?
Answer
Calcium chloride is known to be soluble in water, while barium sulfate is insoluble. Therefore, the correct answer is Row A, which shows calcium chloride as soluble and barium sulfate as insoluble.
Step 4
Use the diagram to describe the structure of a metal and to explain why metals are malleable and conduct electricity.
Answer
The diagram illustrates the metallic structure characterized by a lattice of metal cations surrounded by a sea of delocalized electrons. This unique arrangement allows metals to be malleable, as layers of atoms can easily slide over one another without breaking the metallic bond due to the presence of the delocalized electrons that maintain the structure. Additionally, the free-moving electrons enable metals to conduct electricity efficiently, as they can flow freely through the lattice when an electrical potential is applied.