Question

A saturated solution of non-radioactive sugar was taken and a little radioactive sugar was added to it. A small amount of it gets dissolved in solution and an equal amount of sugar was precipitated. This proves: (a) The equilibrium has been established in the solution (b) Radioactive sugar can displace non-radioactive sugar from its solution.

Short answer

(a) The equilibrium has been established in the solution.

Step-by-step solution

Understanding Saturated Solutions

A saturated solution is one where the maximum amount of solute has been dissolved at a given temperature. If additional solute is added, it should not be able to dissolve unless conditions change (e.g., temperature or pressure).

Effect of Adding Radioactive Sugar

When radioactive sugar is added to the saturated solution, some of it dissolves, and a corresponding amount of non-radioactive sugar precipitates out. This indicates that the solubility limit of the sugar in the solution is maintained.

Interpreting Precipitation and Dissolution

The fact that an equal amount of sugar precipitates as dissolves demonstrates a dynamic equilibrium. The system adjusts by allowing only the same total concentration of solute, maintaining its saturated state.

Concluding the Type of Equilibrium

Since the process results in an equal exchange of dissolved and precipitated sugar molecules without changing the total concentration, it illustrates that equilibrium between dissolved and undissolved sugar has been established, where the rate of dissolution equals the rate of precipitation.

Key concepts

Saturated Solutions

A saturated solution is a fascinating concept in chemistry where the solution contains the maximum concentration of solute possible at a specific temperature and pressure. Imagine you are adding sugar to a glass of water. Initially, the sugar dissolves, making the water sweeter. However, at a certain point, no more sugar can dissolve, even if you keep stirring. This point is called saturation.

In saturated solutions, if you try to add more solute without changing the conditions (like temperature), the undissolved solute will simply remain in solid form. That's because the solution has reached its solubility limit. Therefore:

• A saturated solution maintains a balance between dissolved solute and undissolved solute.
• Temperature or pressure changes can alter this balance and allow more solute to dissolve.

Understanding the concept of saturation helps in tasks like predicting how much solute a solution can hold and determining the effects of changes in conditions.

Precipitation and Dissolution

Precipitation and dissolution are key processes occurring in a solution, especially in a saturated one. When you add a bit of radioactive sugar to a non-radioactive saturated sugar solution, some of it dissolves, while an equivalent amount of non-radioactive sugar precipitates. It's like a swap! The radioactive sugar integrates into the solution, replacing the same amount of its non-radioactive counterpart.

This happens because the solution has reached its capacity to dissolve sugar. Let's break it down:

• **Dissolution:** Radioactive sugar particles dissolve into the solution.
• **Precipitation:** Simultaneously, an equal amount of non-radioactive sugar forms crystals and separates out.

Through these processes, the overall concentration of sugar in the solution does not change. The relationship between precipitation and dissolution is in perfect balance in a saturated solution, ensuring that it remains at its solubility limit.

Dynamic Equilibrium

The term "dynamic equilibrium" describes a situation where the rate of two opposing processes is equal, leading to a stable system. In the case of our sugar solution, dynamic equilibrium occurs between the processes of dissolution and precipitation. This means:

• The rate at which radioactive sugar dissolves equals the rate at which non-radioactive sugar precipitates.
• The overall concentration of dissolved sugar does not change.

This balance ensures that even though molecules continually swap places between the dissolved and undissolved states, the total composition of the solution remains unchanged. It's a dynamic state because the sugar molecules are moving and changing positions constantly, but equilibrium is maintained without altering the concentration.

Dynamic equilibrium showcases the balancing act of nature, where constant changes do not affect the overall state of the system. This principle is crucial for understanding many chemical reactions and processes, highlighting the persistent motion and balance within solutions.