A \(3.20-\mathrm{g}\) sample of a salt dissolves in \(9.10 \mathrm{~g}\) of water to give a saturated solution at \(25^{\circ} \mathrm{C}\). What is the solubility (in \(\mathrm{g}\) salt/ \(100 \mathrm{~g}\) of \(\mathrm{H}_{2} \mathrm{O}\) ) of the salt?

At the heart of many scientific inquiries and practical applications is the concept of chemical solubility. This concept answers the question: How much of a substance (the solute) can be dissolved in a given amount of solvent, such as water, before the solution becomes saturated?
In simple terms, solubility measures the maximum amount of solute that can be dissolved in a solvent at a specific temperature and pressure. This is typically presented in grams per 100 grams of solvent. Chemical solubility is influenced by several factors including the temperature, the nature of the solute and solvent, and the presence of other chemicals. With our salt-water example from the exercise, it's clear that these measures provide a quantitative way to describe how soluble a substance is under given conditions.

• Temperature: Generally, the solubility of solid solutes in liquid solvents increases with temperature.
• Nature of Solute and Solvent: The 'like dissolves like' rule is handy, meaning polar solutes typically dissolve well in polar solvents, and non-polar solutes in non-polar solvents.
• Presence of Other Chemicals: The presence of other substances can either increase or decrease solubility through various interactions.

When calculating the solubility, we need to consider these factors carefully to ensure our results are accurate in predicting how much of a substance can actually be dissolved.

A saturated solution is reached when the maximum amount of solute has been dissolved in a solvent and any additional solute will no longer dissolve. At this point, the system is in a state of dynamic equilibrium: the rate at which the solute dissolves in the solvent is equal to the rate at which it precipitates out.
In our exercise, the given sample forms a saturated solution, which means that the 3.20g of salt represents the maximum amount that can dissolve in 9.10g of water at 25°C. If more salt was added to this mixture, it would simply remain undissolved, visibly settling at the bottom of the container. This particular concept is vital in fields such as pharmacology, where saturation points affect the effectiveness of drugs, or in environmental science, where it influences pollutant absorption.
A saturated solution's concentration is directly related to the solubility of the solute at a specific temperature. Precision in finding this saturation point is crucial for chemists and other professionals who work with chemical solutions regularly.

Water, known as the 'universal solvent', is renowned for its ability to dissolve many substances, which is why solubility in water is a significant topic in chemistry. Solubility in water is specifically important because it has far-reaching implications for both practical applications—such as mixing medicines, cooking, and industrial processes—and natural phenomena, such as the nutrient cycles in bodies of water.

• Calculating Solubility: In our exercise, we show that solubility is calculated by first finding the mass ratio of solute to solvent and then expressing it per 100g of solvent. This aligns with the common way solubility is reported in scientific literature, making comparisons more straightforward.
• Relevance: Understanding solubility in water helps predict how substances will behave in aqueous environments, affecting decisions in pharmaceutical formulation, chemical manufacturing, and environmental management.

To enhance student comprehension of the problem, it's advantageous to provide a practical example: If a salt has a solubility of 35g per 100g of water, you can dissolve up to 35g of that salt in 100g of water at a specific temperature. If you were to add 40g of salt to 100g of water, you would end up with a saturated solution plus 5g of undissolved salt, assuming temperature remains constant.