Question

Design an Experiment You are given a sample of a solid solute and three aqueous solutions containing that solute. How would you determine which solution is saturated, unsaturated, and supersaturated?

Short answer

To determine which solution is saturated, unsaturated, and supersaturated, follow these steps: 1. Prepare three labeled beakers for each solution. 2. Add a small amount of solid solute to each beaker, gently stirring. 3. Observe if the solute dissolves: if it dissolves completely, the solution is unsaturated; if it doesn't dissolve and settles at the bottom, the solution is saturated; if the solution already has a high concentration of solute and doesn't dissolve, it's supersaturated. 4. Heat the supersaturated solution to observe if the undissolved solute dissolves, indicating it has become saturated when heated. 5. Record and analyze your observations, noting the differences in solubility and the effect of temperature on the supersaturated solution.

Step-by-step solution

Gather all necessary materials

Before starting the experiment, make sure you have the solute sample, three aqueous solutions, a stirring rod, three beakers, a hot plate, and a thermometer.

Label and prepare each beaker

Label the three beakers to avoid confusion and help identify each solution's corresponding status. Pour each provided aqueous solution into the respective labeled beaker.

Test solubility of each solution

Add a small amount of the solid solute to each beaker and gently stir using the stirring rod. Observe if the solute dissolves in the solution or not.

Identify unsaturated, saturated, and supersaturated solutions

Based on the results of step 3: - If the solute dissolves completely, the solution is unsaturated. - If the solute does not dissolve and settles at the bottom of the beaker, the solution is saturated. - If there's a high concentration of the solute already present in the solution and the solute does not dissolve, it indicates the solution is supersaturated.

Heat the supersaturated solution

Place the beaker with the supersaturated solution on a hot plate and gradually heat it. As it heats, observe if the undissolved solute begins to dissolve. A supersaturated solution will become saturated when heated, and more solute will dissolve in it.

Record and analyze observations

Once you have clearly identified which solution is unsaturated, saturated, and supersaturated, record your observations. Analyze the differences in solubility for each solution, and note how temperature affected the supersaturated solution.

Key concepts

Solute Solubility

Understanding the concept of solute solubility is crucial for anyone exploring chemistry. Solubility refers to the maximum amount of solute that can dissolve in a solvent at a specific temperature and pressure. It's typically expressed in grams of solute per 100 grams of solvent.

The solubility of solids in liquids often increases with temperature, while gases typically become less soluble as the temperature increases. To illustrate, consider adding sugar, our solute, to water, our solvent. At room temperature, only a certain amount of sugar can dissolve in the water. Once that limit is reached, no more sugar can dissolve, and we would call this a saturated solution.

However, if we were to heat the water, more sugar could be dissolved before reaching a saturation point, demonstrating the temperature dependence of solubility. This characteristic is essential when experimenting with chemical solutions, as understanding the solubility of different substances helps predict how they will behave under various conditions.

Designing a Chemistry Experiment

The design of a chemistry experiment is a methodical process that requires careful planning, precise measurements, and controlled variables. It's a means to answer a scientific question or test a hypothesis.

In the case of determining the saturation level of solutions, one would need to consider the following practical aspects: quantity of solute and solvent, purity of substances involved, temperature control, equipment calibration, and detailed record-keeping.

For example, when trying to determine the state of saturation of solutions, it's key to systematically add the solute to each solution and stir consistently. It is also essential to note any changes in temperature, as this can affect solubility. As the exercise suggests, heating a supersaturated solution may lead to additional solute dissolving, indicating that solubility is dynamic and influenced by environmental conditions. The reliability of the experiment's outcome hinges on replicating conditions across all test samples and accuracy in observations.

Solutions Concentration States

In chemistry, solutions can be classified into three concentration states based on the amount of solute in the solvent: unsaturated, saturated, and supersaturated. Recognizing these states is fundamental to understanding solution chemistry.

An unsaturated solution is one where there is less solute than the maximum amount that can be dissolved. This state indicates that if more solute is introduced, it will readily dissolve without needing to alter the conditions.

A saturated solution contains the maximum amount of solute that can be dissolved at a given temperature and pressure. Any additional solute added will remain undissolved, settling at the bottom.

A supersaturated solution, on the other hand, holds more solute than would typically dissolve at the current conditions. It is achieved by dissolving the solute at an elevated temperature and then cautiously cooling the solution. Once supersaturated, solute may precipitate out of the solution spontaneously or upon addition of a seed crystal, reverting to a saturated state. The ability to identify these states is key to many applications, including the formation of crystals, manufacturing of pharmaceuticals, and crafting of culinary delicacies.