Solutions Worksheet Answer Key Pdf - Fill Online, Printable ... - Free Printable

Problem Analysis:

The task involves understanding and describing the concept of a solute in solutions, providing examples, and explaining how solute concentration is expressed. Let's break this down step by step.

---

Task 1: Define the term "solute"

A solute is the substance that is dissolved in a solution. It is present in a smaller amount compared to the solvent and exists as individual molecules or ions in the solution. The solute is uniformly distributed throughout the solvent.

- Key Points:
- The solute is the component being dissolved.
- It can be a solid, liquid, or gas.
- In a solution, the solute is dispersed at the molecular or ionic level.

---

Task 2: Provide two examples of solutes in everyday life

#### Example 1: Sugar in water
- Solute: Sugar (sucrose)
- Solvent: Water
- Solution: Sugar dissolves in water to form a homogeneous mixture. Here, sugar is the solute because it is the substance being dissolved in water.

#### Example 2: Salt in water
- Solute: Sodium chloride (NaCl)
- Solvent: Water
- Solution: When salt dissolves in water, sodium ions (Na⁺) and chloride ions (Cl⁻) are dispersed throughout the water. Sodium chloride is the solute.

---

Task 3: Explain how the concentration of a solute is expressed

The concentration of a solute in a solution is a measure of the amount of solute present relative to the amount of solvent or the total volume of the solution. There are several ways to express concentration:

1. Molarity (M):
- Definition: Molarity is the number of moles of solute per liter of solution.
- Formula:
\[
\text{Molarity (M)} = \frac{\text{moles of solute}}{\text{liters of solution}}
\]
- Example: A 1 M solution of NaCl means there is 1 mole of NaCl dissolved in 1 liter of solution.

2. Mass Percent (%):
- Definition: Mass percent is the mass of the solute divided by the total mass of the solution, multiplied by 100.
- Formula:
\[
\text{Mass Percent} = \left( \frac{\text{mass of solute}}{\text{total mass of solution}} \right) \times 100
\]
- Example: If 5 g of NaCl is dissolved in 95 g of water, the mass percent is:
\[
\text{Mass Percent} = \left( \frac{5}{5 + 95} \right) \times 100 = 5\%
\]

3. Molality (m):
- Definition: Molality is the number of moles of solute per kilogram of solvent.
- Formula:
\[
\text{Molality (m)} = \frac{\text{moles of solute}}{\text{kilograms of solvent}}
\]
- Example: A 1 m solution of NaCl means there is 1 mole of NaCl dissolved in 1 kg of water.

4. Parts per Million (ppm):
- Definition: ppm is used for very dilute solutions and represents the mass of solute per million units of mass of the solution.
- Formula:
\[
\text{ppm} = \left( \frac{\text{mass of solute}}{\text{total mass of solution}} \right) \times 10^6
\]
- Example: A solution with 1 mg of solute in 1 kg of solution has a concentration of 1 ppm.

---

Task 4: Additional Notes on Solubility

- Polar solvents dissolve polar solutes: Polar solvents (e.g., water) dissolve polar solutes (e.g., NaCl) due to electrostatic interactions.
- Nonpolar solvents dissolve nonpolar solutes: Nonpolar solvents (e.g., hexane) dissolve nonpolar solutes (e.g., oil) due to London dispersion forces.
- Like dissolves like: This principle explains why certain solutes dissolve in specific solvents based on their polarity or nonpolarity.

---

Final Answer

1. Definition of Solute: The substance that is dissolved in a solution, present in a smaller amount compared to the solvent.
2. Examples:
- Sugar in water: Solute = Sugar, Solvent = Water.
- Salt in water: Solute = Sodium chloride (NaCl), Solvent = Water.
3. Concentration Expressions:
- Molarity (M): Moles of solute per liter of solution.
- Mass Percent (%): Mass of solute divided by total mass of solution, multiplied by 100.
- Molality (m): Moles of solute per kilogram of solvent.
- Parts per Million (ppm): Mass of solute per million units of mass of the solution.

\boxed{\text{See detailed explanation above.}}