What is the Difference Between Concentration and Solubility

Concentration and solubility are both important concepts in chemistry, especially in understanding the behavior of solutions. Understanding the difference between concentration and solubility is fundamental for predicting and manipulating the properties of solutions.

What is the difference between concentration and solubility? Concentration is the amount of solute dissolved in a unit quantity of solution whereas solubility is the maximum amount of solute that can dissolve in a given amount of solvent under specific conditions (usually temperature and pressure).

Key Areas Covered

1. What is Concentration  
      – Definition, Features 
2. What is Solubility
      – Definition, Features 
3. Similarities Between Concentration and Solubility 
      – Outline of Common Features
4. Difference Between Concentration and Solubility
      – Comparison of Key Differences
5. FAQ: Concentration and Solubility
      – Frequently Asked Questions

Key Terms

Concentration, Solubility

What is Concentration

Concentration refers to the amount of solute dissolved in a unit quantity of solution. This can be expressed in various ways, like molarity (moles of solute per liter of solution) or percent by weight (grams of solute per 100 grams of solution). Concentration is essential because it dictates how fast reactions happen, the strength of solutions, and various other properties.

Chemists use different ways to express concentration depending on the situation.

Mass concentration: This is simply the mass of solute per unit volume of solution.

Molar concentration (Molarity): This is the most common unit and tells you the number of moles of solute per liter of solution.

Volume concentration: This is used for solutions where both solute and solvent are liquids. It’s expressed as a percentage of the total volume occupied by the solute. For example, 10% (v/v) alcohol solution means 10% of the solution’s volume is pure alcohol.

What is Solubility

Solubility is the ability of a substance (solute) to dissolve in another substance (solvent) to form a solution. Solubility is due to the intermolecular attraction forces. The main principle of solubility is polarity.

Polar solutes, which are molecules with uneven charge distribution, tend to dissolve well in other polar solvents. For example, sugar, which is a polar compound, dissolves in water, which is again another polar solvent, as their positive and negative charges can interact favourably.

On the other hand, nonpolar solutes (no uneven charge distribution) are more comfortable with other nonpolar solvents. Oil dissolving in grease is an example of nonpolar compounds dissolving in non-polar solvents. Hence, it could be said that like dissolves like.

The dissolving process itself involves solvation, where solvent molecules surround and interact with the solute particles. This disrupts the solute’s intermolecular forces, allowing it to disperse uniformly throughout the solution.

Two factors affecting solubility are temperature and pressure. An increase in temperature increases solubility while an increase in pressure favors higher solubility(of gas molecules).

Similarities Between Concentration and Solubility

1. Both are related to the amount of solute.
2. Changes in temperature can influence both.
3. Both help to understand and predict the behavior of solutions.

Difference Between Concentration and Solubility

Definition

• Concentration is the amount of solute dissolved in a unit quantity of solution whereas solubility is the maximum amount of solute that can dissolve in a given amount of solvent under specific conditions (usually temperature and pressure).

Units

• Concentration is expressed in various units depending on the type of concentration. Examples include grams per liter (g/L), molarity (M), or percent by volume (%v/v). However, solubility is typically given in grams of solute per 100 milliliters of solvent (g/100 mL) or grams per liter of solvent (g/L).

Value

• Concentration is a dynamic value, whereas solubility is a fixed property of a particular solute-solvent pair at a specific temperature and pressure.

Conclusion

Concentration denotes the amount of solute within a specific quantity of solution, expressed through units like molarity or mass concentration. Solubility indicates the maximum solute quantity that can dissolve in a given solvent under defined conditions, impacted by factors such as temperature and pressure. This is the main difference between concentration and solubility. 

FAQ: Concentration and Solubility

1. What factors affect solubility?

Solubility is mainly affected by 4 factors: temperature, pressure, polarity and molecular size. 

1. Temperature: Higher temperatures increase solubility for solids but can decrease it for gases.
2. Pressure: Higher pressure increases gas solubility in liquids.
3. Polarity: Solubility depends on the polarity match between solute and solvent.
4. Molecular size: Smaller molecules dissolve more readily due to better fit between solvent molecules.

2. Does higher concentration mean more solute?

A higher concentration indicates a greater amount of solute dissolved in a solution. Concentration quantifies the ratio of solute particles to the total volume or mass of the solution. Therefore, a higher concentration implies a larger number of solute particles dispersed within the solvent.

3. Which solution has the highest concentration?

The solution with the highest concentration would be a supersaturated solution, wherein the amount of solute exceeds the solvent’s capacity to dissolve it under normal conditions. In such a solution, the concentration surpasses that of a saturated solution.

4. What do you mean by unsaturation?

Unsaturation means that the concentration of the solute in the solution is lower than its maximum solubility at the given temperature and pressure. So, if the amount of solute present is less than what the solvent could potentially dissolve under those conditions, the solution is considered unsaturated.

5. Is solubility the same as molarity?

The solubility is not the same as molarity. Solubility is the ability of a substance to dissolve in a solvent and form a solution, while molarity is a unit of concentration expressed as the number of moles of dissolved solute per liter of solution.

Reference:

1. “Solubility Chemistry.” Encyclopedia Britannica.
2. “Concentrated Definition (Chemistry).” Thought Co.

Image Courtesy:

1. “Solubility Vs Temperature” (Public Domain) via Commons Wikimedia
2. “Palladium catalyst solutions with varying concentration” By [email protected] – Own work (CC BY-SA 4.0) via Commons Wikimedia