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Bromine is a liquid at room temperature and vaporises readily - Edexcel - GCSE Chemistry - Question 8 - 2022 - Paper 1
Question 8
Bromine is a liquid at room temperature and vaporises readily. Bromine has a simple molecular structure. (a) Part of the structure of graphene is shown in Figure 5... show full transcript
Worked Solution & Example Answer:Bromine is a liquid at room temperature and vaporises readily - Edexcel - GCSE Chemistry - Question 8 - 2022 - Paper 1
Step 1
Explain why graphene will be a good conductor of an electric current.
Answer
Graphene is an excellent conductor of electricity primarily because of its unique structure. It consists of a single layer of carbon atoms arranged in a two-dimensional honeycomb lattice.
- Delocalized Electrons: The structure allows for the presence of delocalized electrons that can move freely across the surface. This mobility of electrons facilitates electrical conduction.
- High Electron Density: The high electron density in the graphene sheet means that even minimal applied electric fields can significantly influence the motion of these electrons, thereby conducting electricity efficiently.
- Low Resistance: Due to its unique bonding and low resistance to electron movement, graphene demonstrates exceptional conductive properties comparable to metals.
Step 2
Explain why potassium chloride has a high melting point.
Answer
Potassium chloride (KCl) has a high melting point due to its ionic structure.
- Ionic Bonds: The compound is formed from potassium ions (K⁺) and chloride ions (Cl⁻), which are held together by strong electrostatic forces of attraction known as ionic bonds. These bonds require a significant amount of energy to break.
- Lattice Structure: In solid KCl, these ions are arranged in a rigid lattice structure, maximizing the strength of the ionic interactions.
- Energy Requirement: To melt the solid into a liquid, substantial thermal energy is needed to overcome these strong ionic bonds, resulting in a high melting point of 770°C.
Step 3
Describe what information can be obtained from each representation including the limitations of these representations of methane.
Answer
The different representations of methane (CH₄) provide various insights into its structure and bonding, along with certain limitations:
- Structure A: This shows the molecular formula (CH₄), indicating the ratio of carbon to hydrogen atoms; however, it lacks structural detail.
- Structure B: This representation highlights the bonding within the molecule, illustrating the four covalent bonds carbon makes with hydrogen. It does not depict the actual three-dimensional arrangement.
- Structure C: By revealing the spatial arrangement of atoms in a 3D form, this structure communicates the tetrahedral geometry. Yet, it does not illustrate bond angles explicitly.
- Structure D: This drawing identifies bond positions, but once again, it may not fully represent the actual bonding dynamics in three dimensions.
- Structure E: Presents a more stylized view but provides no specific information about bond lengths or angles between atoms. No representation fully captures the complexity of molecular interactions. Thus, each representation serves a purpose but also has limitations in conveying the complete molecular behavior.