15.2. Aqueous Solutions http://www.ck12.org
dissolution of a non-acidic molecular substance, only the intermolecular interactions that hold individual molecules
together are disrupted.
Scenario 3 –Sand Added to Water
If we were to mix sand and water, no solution would form. No matter how long we stirred this mixture, the sand
would still settle out to the bottom. Sand and water combine to make a heterogeneous mixture. TheFigure15.13
shows this on a large scale.
FIGURE 15.13
Sand mixing with water.In order to create a homogeneous aqueous solution, we need the solute to be soluble in water. Sand isinsolublein
water, and we can easily see that the two substances remain separate when mixed. The conductivity of this system
would also be similar to that of pure water, because neither component is conductive on its own, and no real change
occurs when they are mixed together.
Lesson Summary
- Water is a versatile solvent that can dissolve many ionic and polar molecular solutes to make aqueous solutions.
- The ability of water to dissolve polar and ionic substances is due to its own polarity, which provides partial
positive and negative charges to stabilize isolated ions and molecules. - A homogeneous solution is created when a solute dissolves completely into a solvent. In a solution, we cannot
visually distinguish between the solute and solvent. - Ionic substances dissociate into ions when they dissolve in water, but most molecular substances do not.
- Not all substances are soluble in water.
Lesson Review Questions
- How can a solution be classified as aqueous?
- What distinguishes solvent and solute?
- How are dissolution and dissociation related?