Solutes and Solvents

During our latest mini lab, we experimented with sugar and salt solutions. A solution is defined as a “homogeneous mixture of two or more pure substances”, and is composed of solvents and solutes. A solute is present in greatest abundance, and is usually in the form of water. A solute is any other substance in the solution. In our experiment, we worked with multiple solutions, with the goal of differentiating them. We differentiated the salt solution, sugar solution, and DI water by the level of cloudiness present in the water, but this was just out of luck. Generally, solutions are not easily distinguishable. We tested with a light bulb for conductivity to ensure our observations, which is what would usually be done in this situation. The conductivity present is a result of charged ions in the solution.

The difference between an electrolyte and a nonelectrolyte is that an electrolyte dissociates into ions when dissolved in water, while a nonelectrolyte may dissolve, but it does not dissociate into ions when it does so. Particle diagrams can be created to represent these changes. Particle diagrams include individual ions/particles surrounded by the solute, which, in this case, is water. They appear this way because when something dissolves, it is engulfed by the abundant material. Depending on the charge of the particle, the hydrogen of the water molecules may face away from or towards the surrounded material. For example, a diagram of our sodium chloride solution would show both sodium and chloride ions isolated with water encircling them. The chloride molecule would be displayed as larger because of its greater negative charge and corresponding electron cloud. As a result of the negative charge, the chloride molecule would have the slightly positive hydrogen heads of water facing it, because opposites attract. The opposite would occur with the sodium molecule. It would be shown as smaller, and as a result of its positive charge, would attract the slightly negative oxygen atom.

AnCl in crystal structure and in water

A particle diagram can also be created for a sugar solution. In this instance, the sugar molecule would be engulfed by water molecules, as displayed below. 

Sources:

Flipped Notes 4.2 B and C

http://www.thunderboltkids.co.za/Grade6/02-matter-and-materials/chapter4.html

http://www.biology.arizona.edu/biochemistry/tutorials/chemistry/page3.html

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