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Multiple Choice
Which of the following best explains why polar molecules, such as sugar, dissolve in water?
A
Polar molecules dissolve in water only if they are ionic compounds.
B
Water's nonpolar nature repels polar molecules, preventing them from dissolving.
C
Water can only dissolve nonpolar molecules due to hydrophobic interactions.
D
Water's polarity allows it to surround and separate polar molecules, causing them to dissolve.
Verified step by step guidance
1
Understand the concept of polarity: Polar molecules have regions of partial positive and partial negative charges due to unequal sharing of electrons in their bonds. Water is a polar molecule because its oxygen atom is more electronegative than its hydrogen atoms, creating a dipole moment.
Recognize the principle of 'like dissolves like': Polar solvents, such as water, are effective at dissolving polar substances because the partial charges in the solvent can interact with the partial charges in the solute.
Explain how water interacts with polar molecules: The positive region of water (hydrogen atoms) is attracted to the negative regions of the polar molecule, while the negative region of water (oxygen atom) is attracted to the positive regions of the polar molecule. This interaction helps break apart the polar molecules and disperse them in the solution.
Describe the process of hydration: Once the polar molecules are separated, water molecules surround them, forming a hydration shell. This stabilizes the polar molecules in the solution and prevents them from recombining.
Conclude why water dissolves polar molecules: Water's polarity allows it to effectively surround and separate polar molecules, disrupting their intermolecular forces and causing them to dissolve.