Chemistry: Solutions

Solution

• A solution consists of two major components: solute and solvent.
• A solution is a homogeneous mixture where the solute is absolutely soluble in the solvent.
• The definition of a solution is a homogeneous mixture of two or more than two components.

Solute and Solvent

• A solution has one solvent and one or more than one solute.
• Example: Lemonade (water as solvent and sugar and salt as solutes).

Classification of Solutions

• Based on the number of solutes and solvents, solutions can be classified into:
  • Binary solution (one solute and one solvent)
  • Ternary solution (one solvent and two solutes)
  • Quaternary solution (one solvent and three solutes)
• If not specified, a solution is assumed to be a binary solution.

Concentration of a Solution

• Concentration is a measure of the amount of solute in a solution.
• Expressions of concentration can vary, but they all convey the same information: how much solute is present in a given amount of solution.

Molarity (M)

• Molarity (M) is the number of moles of solute present in one liter of solution.
• Molarity is represented by the symbol M (capital M).
• Formula: M = moles of solute / volume of solution (in liters)
• Example: 3 M NaOH solution means 3 moles of NaOH are present in one liter of solution.

Molality (m)

• Molality (m) is the number of moles of solute present in one kilogram of solvent.
• Molality is represented by the symbol m (small m).
• Formula: m = moles of solute / mass of solvent (in kg)
• Example: 3 m NaOH solution means 3 moles of NaOH are present in one kilogram of solvent.

Mass by Volume Percentage

• Mass by volume percentage is the mass of solute present in 100 milliliters of solution.
• Formula: mass by volume percentage = (mass of solute in grams) / (volume of solution in milliliters) × 100
• Example: 10% mass by volume percentage NaOH solution means 10 grams of NaOH are present in 100 milliliters of solution.

Mass by Mass Percentage

• Mass by mass percentage is the mass of solute present per 100 grams of solution.
• Formula: mass by mass percentage = (mass of solute in grams) / (mass of solution in grams) × 100
• Example: 10% mass by mass percentage NaOH solution means 10 grams of NaOH are present in 100 grams of solution.### Calculating Mass of Solvent
• Mass of solution = mass of solute + mass of solvent
• Given 100 grams of solution and 10 grams of solute, mass of solvent = 100 - 10 = 90 grams
• Convert mass of solvent from grams to kilograms: 90 grams ÷ 1000 = 0.09 kg

Calculating Molality

• Molality = moles of solute ÷ mass of solvent in kilograms
• Calculate molality using the formula: moles of solute ÷ 0.09 kg

Calculating Molarity

• Molarity = moles of solute ÷ volume of solution in liters
• Calculate volume of solution using the density of the solution (if given)
• Convert volume from milliliters to liters

Volume by Volume Percentage

• Volume by volume percentage = volume of solute in milliliters ÷ volume of solution in milliliters × 100
• Formula: volume of solute ÷ volume of solution × 100
• Example: 10 volume by volume aqueous NaOH solution means 10 mL of solute is present in 100 mL of solution

Mole Fraction

• Mole fraction is represented by x (or χ)
• Mole fraction is a fraction, always between 0 and 1
• Formula for mole fraction of a component: moles of component ÷ total moles present in the solution
• Example: mole fraction of A = moles of A ÷ (moles of A + moles of B)
• The sum of mole fractions of all components is always equal to 1
• If mole fractions of two components are known, the third component's mole fraction can be calculated by subtracting them from 1

Parts Per Million (PPM)

• Parts per million is similar to percentage, but with a different scale
• Formula: mass of solute in grams ÷ mass of solution in grams × 10^6
• PPM is used to calculate the number of grams of solute per 10^6 grams of solution
• Example: 3 ppm of Cl2 means 3 grams of solute is present in 10^6 grams of solution### Concentration Terms and Vapor Pressure
• The concept of concentration terms is crucial in understanding vapor pressure.
• Vapor pressure is the maximum pressure exerted by a vapor in equilibrium with a liquid.
• At a saturated condition, the pressure exerted by vapor molecules is equal to the vapor pressure.

Vapor Pressure and Boiling Point

• Imagine a closed container with water inside, where water molecules (particles) are in constant motion.
• Particles on the surface of the liquid have a higher energy and are unbalanced, wanting to escape the surface.
• When a particle on the surface gains enough energy, it escapes the surface, creating a vapor and exerting pressure on the container walls.
• At a particular temperature, an equilibrium is reached, where equal numbers of molecules are converted into the vapor phase and the liquid phase.
• This equilibrium point is known as the saturated vapor or saturation point.
• The pressure exerted at this point is the vapor pressure.

Characteristics of Vapor Pressure

• Vapor pressure is constant at a particular temperature.
• It depends only on the temperature and nature of the liquid.
• Vapor pressure does not depend on the volume of the container or the amount of the liquid.

Raoult's Law

• Raoult's law states that the partial pressure of any component in a solution is proportional to the mole fraction of that component in the liquid solution.
• The partial pressure of a component is directly proportional to its mole fraction.
• If the mole fraction of a component is more, it will exert more pressure.
• Raoult's law is used to calculate the vapor pressure of a mixture of two volatile components.

Dalton's Law

• Dalton's law states that the partial pressure of a component in the vapor phase is equal to the mole fraction of that component in the vapor phase multiplied by the total pressure.
• Dalton's law is used to derive expressions for the partial pressure of a component in the vapor phase.

Vapor Pressure of a Mixture of Two Volatile Components

• The total pressure of a mixture of two volatile components is equal to the sum of the partial pressures of the two components.
• The partial pressure of each component can be calculated using Raoult's law.
• The total pressure can be calculated using the expression: p_total = p_a + p_b.

Raoult's Law and Non-Volatile Solutes

• If one of the components in a solution is non-volatile, it means that it does not have any vapor pressure.
• The vapor pressure of a solution with a non-volatile solute is only due to the volatile solvent.
• The partial pressure of the volatile solvent is directly proportional to its mole fraction in the solution.

Solution

• A solution is a homogeneous mixture where the solute is absolutely soluble in the solvent.
• It consists of two major components: solute and solvent.

Solute and Solvent

• A solution has one solvent and one or more than one solute.
• Example: Lemonade (water as solvent and sugar and salt as solutes).

Classification of Solutions

• Solutions can be classified based on the number of solutes and solvents.
• Types of solutions: binary solution (one solute and one solvent), ternary solution (one solvent and two solutes), and quaternary solution (one solvent and three solutes).

Concentration of a Solution

• Concentration is a measure of the amount of solute in a solution.
• Expressions of concentration convey the same information: how much solute is present in a given amount of solution.

Molarity (M)

• Molarity (M) is the number of moles of solute present in one liter of solution.
• Formula: M = moles of solute / volume of solution (in liters).
• Example: 3 M NaOH solution means 3 moles of NaOH are present in one liter of solution.

Molality (m)

• Molality (m) is the number of moles of solute present in one kilogram of solvent.
• Formula: m = moles of solute / mass of solvent (in kg).
• Example: 3 m NaOH solution means 3 moles of NaOH are present in one kilogram of solvent.

Mass by Volume Percentage

• Mass by volume percentage is the mass of solute present in 100 milliliters of solution.
• Formula: mass by volume percentage = (mass of solute in grams) / (volume of solution in milliliters) × 100.
• Example: 10% mass by volume percentage NaOH solution means 10 grams of NaOH are present in 100 milliliters of solution.

Mass by Mass Percentage

• Mass by mass percentage is the mass of solute present per 100 grams of solution.
• Formula: mass by mass percentage = (mass of solute in grams) / (mass of solution in grams) × 100.
• Example: 10% mass by mass percentage NaOH solution means 10 grams of NaOH are present in 100 grams of solution.

Calculating Mass of Solvent

• Mass of solution = mass of solute + mass of solvent.
• Given 100 grams of solution and 10 grams of solute, mass of solvent = 100 - 10 = 90 grams.

Calculating Molality

• Molality = moles of solute ÷ mass of solvent in kilograms.
• Calculate molality using the formula: moles of solute ÷ 0.09 kg.

Calculating Molarity

• Molarity = moles of solute ÷ volume of solution in liters.
• Calculate volume of solution using the density of the solution (if given).
• Convert volume from milliliters to liters.

Volume by Volume Percentage

• Volume by volume percentage = volume of solute in milliliters ÷ volume of solution in milliliters × 100.
• Formula: volume of solute ÷ volume of solution × 100.
• Example: 10 volume by volume aqueous NaOH solution means 10 mL of solute is present in 100 mL of solution.

Mole Fraction

• Mole fraction is represented by x (or χ).
• Mole fraction is a fraction, always between 0 and 1.
• Formula for mole fraction of a component: moles of component ÷ total moles present in the solution.
• Example: mole fraction of A = moles of A ÷ (moles of A + moles of B).

Parts Per Million (PPM)

• Parts per million is similar to percentage, but with a different scale.
• Formula: mass of solute in grams ÷ mass of solution in grams × 10^6.
• PPM is used to calculate the number of grams of solute per 10^6 grams of solution.
• Example: 3 ppm of Cl2 means 3 grams of solute is present in 10^6 grams of solution.

This quiz covers the definition, components, and classification of solutions in chemistry. Learn about the differences between solute and solvent, and how to identify them in various examples.