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QLDChemistryQuick questions
Unit 2: Molecular interactions and reactions
Quick questions on Water as a solvent and the dissolution of ionic and polar substances (QCE Chemistry Unit 2)
8short Q&A pairs drawn directly from our worked dot-point answer. For full context and worked exam questions, read the parent dot-point page.
What is the structure of water?Show answer
Water has the molecular formula H_2O. The O atom is sp3-like with two bond pairs (to H) and two lone pairs. VSEPR predicts a bent shape with H-O-H angle around 104.5 degrees.
What is hydrogen bonding in water?Show answer
H bonded to O (one of N, O, F) can hydrogen bond. Each water molecule has:
What is dissolution of ionic compounds (ion-dipole interaction)?Show answer
When an ionic solid such as NaCl is placed in water:
What are dissolution of polar molecular substances?Show answer
Polar molecules with hydrogen-bond donor or acceptor groups dissolve readily because they can substitute for water-water hydrogen bonds with comparable strength water-solute hydrogen bonds.
What is "Like dissolves like" as a heuristic?Show answer
Polar / hydrogen-bonding substances dissolve in polar / hydrogen-bonding solvents.
What is q1?Show answer
Explain, with a diagram in words, how water dissolves sodium chloride. [3 marks]
What is q2?Show answer
Predict and justify whether (a) hexane (b) ethanol are miscible with water. [4 marks]
What is q3?Show answer
A QCAA data-test gives solubilities at : water; water. (a) Account for the difference. (b) Predict effect of warming.