Question

The same amount of red-colored Kool-Aid crystals is added to a still glass of thick sugar water and a still glass of disrilled water. Both are the same temperature. Neither are stirred. Which should become uniform in color first?

Short answer

The distilled water should become uniform in color first.

Step-by-step solution

Understand the Scenario

We have two glasses: one with sugar water and the other with distilled water, both at the same temperature. Red Kool-Aid crystals are added to both.

Identify the Solvent Properties

Recognize that distilled water is a pure solvent, while sugar water is a solution with sugar dissolved in it, making it thicker or more viscous.

Determine Diffusion Rates

Diffusion is the process by which particles spread out evenly in a liquid. In this case, the rate of diffusion of Kool-Aid depends on the viscosity of the liquid.

Compare Viscosity Effects

The thicker sugar water has a higher viscosity compared to distilled water. Higher viscosity implies slower diffusion rates.

Predict Uniformity Outcome

Since particles in a less viscous liquid (distilled water) can move more freely, the diffusion of Kool-Aid crystals should be faster in distilled water, making the color uniform sooner in distilled water.

Key concepts

Viscosity

Viscosity is like the stickiness or thickness of a liquid. Imagine trying to swim through syrup compared to swimming in water.
The syrup would be harder to move through because it's thicker. This thickness impacts how substances spread in a liquid, a process known as diffusion.

• High viscosity means the liquid is thicker, like honey or syrup.
• Low viscosity means the liquid is thinner, like water.

In the experiment with Kool-Aid, the sugar water has high viscosity due to the dissolved sugar. This thickness slows down the movement of particles, causing slower diffusion rates.

Solutions

When we talk about solutions, we're referring to mixtures of two or more substances. In a solution, particles from one substance are evenly distributed within another.
There are many types of solutions, like sugar dissolved in water.
Solutions have certain properties:

• A solvent, which is the substance in which another is dissolved (in this case, water).
• A solute, such as sugar or Kool-Aid, which is the dissolved substance.

In the scenario discussed, sugar water is a solution because it contains sugar dispersed in water, making it different from pure distilled water.

Diffusion Rates

Diffusion is the process where particles spread from an area of higher concentration to an area of lower concentration until they're uniformly distributed. The rate at which diffusion occurs can be influenced by several factors.
One critical factor is viscosity - the thicker the liquid, the harder it is for particles to move around.
Water, being less viscous, allows Kool-Aid crystals to spread quickly and achieve uniform color faster compared to sugar water. Some points to consider regarding diffusion rates:

• Higher viscosity leads to slower diffusion.
• Temperature can also affect diffusion speed, though not a variable in our current scenario.

By understanding diffusion rates, we learn why some solutions mix faster than others.

Solvent Properties

Solvents play a crucial role in dissolving substances (the solutes) to create solutions.
The properties of a solvent, like its viscosity and purity, greatly influence how substances diffuse in it.
In our example, distilled water serves as a purer solvent compared to sugar water:

• Distilled water has no additional substances, allowing molecules to move freely.
• The absence of other solutes like sugar leads to lower viscosity in distilled water.

These properties of the solvent determine how fast and effectively Kool-Aid crystals can spread through the liquid. This highlights the importance of solvent selection when predicting the behaviors of solutions.