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This question is about ionic and simple covalent compounds - OCR Gateway - GCSE Chemistry: Combined Science - Question 14 - 2020 - Paper 1
Question 14
This question is about ionic and simple covalent compounds. Look at the information about two compounds, Y and Z. | Compound Y | Compound Z | |---... show full transcript
Worked Solution & Example Answer:This question is about ionic and simple covalent compounds - OCR Gateway - GCSE Chemistry: Combined Science - Question 14 - 2020 - Paper 1
Step 1
State if Y is ionic or simple covalent compound
Answer
Compound Y is an ionic compound. This conclusion is based on its high melting point of 807 °C and boiling point of 1465 °C, which are typical characteristics of ionic compounds. They have strong electrostatic forces between ions, requiring significant energy to break.
Step 2
State if Z is ionic or simple covalent compound
Answer
Compound Z is a simple covalent compound. The low melting point of -95 °C and boiling point of 69 °C suggest weak intermolecular forces, typical of covalent substances. Additionally, it does not conduct electricity, further indicating it does not have free ions present.
Step 3
Explain your decision using ideas about structure and bonding
Answer
In ionic compounds, the lattice structure formed by the strong attraction between positively and negatively charged ions accounts for their high melting and boiling points. In contrast, simple covalent compounds consist of molecules held together by weaker van der Waals forces, leading to lower melting and boiling points. The electrical conductivity of Compound Y, which conducts in molten state, further supports its ionic nature as ions are free to move. Conversely, Compound Z's inability to conduct electricity implies that it lacks free-moving charged particles, characteristic of covalent compounds.