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8. Bromine is a liquid at room temperature and vaporises readily - Edexcel - GCSE Chemistry - Question 8 - 2022 - Paper 1
Question 8
8. Bromine is a liquid at room temperature and vaporises readily. Bromine has a simple molecular structure. (a) Which row of the table shows the most likely melting... show full transcript
Worked Solution & Example Answer:8. Bromine is a liquid at room temperature and vaporises readily - Edexcel - GCSE Chemistry - Question 8 - 2022 - Paper 1
Step 1
(b) Explain why graphene will be a good conductor of an electric current.
Answer
Graphene is a good conductor of electric current due to its unique arrangement of carbon atoms in a two-dimensional hexagonal lattice. This structure allows for the delocalization of π (pi) electrons. The mobility of these free electrons enables efficient conduction of electricity. Additionally, the high degree of crystalline order in graphene contributes to low electrical resistance.
Step 2
(c) Explain why potassium chloride has a high melting point.
Answer
Potassium chloride has a high melting point due to the strong ionic bonds formed between potassium ions (K⁺) and chloride ions (Cl⁻). The electrostatic forces of attraction between these oppositely charged ions result in a strong ionic lattice structure. It requires a significant amount of energy to break these bonds during melting, leading to the high melting point of 770°C.
Step 3
(d) Describe what information can be obtained from each representation including the limitations of these representations of methane.
Answer
A. The structural formula shows that methane has one carbon atom and four hydrogen atoms, indicating the molecular composition.
B. The displayed formula provides insight into the bonding within the molecule, showing how hydrogen atoms are bonded to the carbon atom but lacks 3D spatial relationships.
C. The ball-and-stick model offers a visual representation of the molecular geometry and indicates the tetrahedral arrangement of the hydrogen atoms around the carbon atom.
D. The space-filling model illustrates the relative sizes of the atoms making up the molecule and their overall volume but does not depict bond angles or the arrangement of atoms.
E. The molecular formula simply conveys the ratio of carbon to hydrogen but does not provide detailed structural information.
Limitations of these representations include the inability of the 2D structures to adequately convey 3D shapes and spatial relationships, as well as ambiguities in bond characteristics.