Physical Properties of Solutions

• Physical properties of solution

What is a solution?

• A solution is a homogeneous mixture of two or more substances
• Homogeneous mixtures have a uniform composition

Solute and Solvent

• Solutions have two main parts: the solute and the solvent
• The solute is the substance in the minority of the solution and is the part that is dissolved
• In salt water, the solute is salt
• The solvent is the substance in the majority of the solution and is the part where the solute is dissolved
• In salt water, the solvent is water

Types of Solutions

• Solutions can be classified based on physical states of solute and solvents, including gaseous, liquid and solid solutions

Gaseous Solutions

• Gases spontaneously mix together in any proportion
• A smaller amount of one gas (solute) dissolves in a larger amount of gas (solvent)
• Both solute and solvent are gases
• In the example of dry air, Oxygen is 21% and Nitrogen is 78%

Liquid Solutions

• Liquid solutions are the most common
• They can be obtained by dissolving a gaseous, liquid, or solid solute

Gaseous Solute in a Liquid Solvent

• A gas dissolves in a liquid to form a gas-liquid solution ex carbonated warer

Liquid Solute in a Liquid Solvent

• When a liquid dissolves in another liquid, it makes a liquid-liquid solution ex alcohol in water

Solid Solutions

• Generally called alloys, where two or more metals are present
• Mercury alloys are called amalgams, and they can be liquid or solid

Types of Solid Solutions

• Substitutional Solid Solution, where atoms of metal P are replaced with atoms of metal Q to produce bronze
• Interstitial solid solutions

Solid Formation of Stalactites and Stalagmites in Caves

• Stalactites and stalagmites in caves are formed from solutions
• Water containing dissolved minerals flows through rocks at ceiling of cave
• Minerals are left behind when drops evaporate
• Stalactites develop downward and stalagmites upwards

Types of Solutions Based on Solute Dissolution

• A saturated solution contains the maximum amount of a solute that will dissolve in a given solvent at a specific temperature
• An unsaturated solution contains less solute than the solvent has the capacity to dissolve at a specific temperature
• A supersaturated solution contains more solute than a saturated solution at a specific temperature

Energies of Solution Formation

• "Like Dissolves Like"
• Step 1: Separate the solution into individual parts of the solute (expanding the solute) i.e. ΔH1
• Step 2: Overcome intermolecular forces in the solvent to make room for the solute (expanding the solute) i.e. ΔH2.
• Step 3: Allow the solute and solvent to interact to form the solution i.e. ΔH3
• Enthalpy of hydration is step 1 and step 2 combined into 1 step

Concentration Units

• The concentration of a solution is the amount of solute present in a given quantity of solvent or solution

Formulas

• % by mass =
• % by volume =
• Mole Fraction (X) =
• Molarity (M) =
• Molality (m) =
• Parts per million = ppm = X

Parts Per Million (PPM)

• The amount of the solute present in one million parts of the solution
• 1 ppm is one part by weight, or volume, of solute in 1 million parts by weight, or volume, of solution
• 1PPM = 1mg/L = 1µg/mL

Water Contamination Example

• If there is 1 mg of a chemical in 1 liter (1 kg) of water, the concentration is 1 PPM
• For every 1 million parts of water, there is 1 part of the chemical

Solution Stoichiometry example problems

• 15g of NaCl was dissolved in 225g of water; mass percent of NaCl in the solution can be determined
• 25mL of Methanol (d = 0.792 g/cm^3 is mixed with 150mL of water (d=1g/cm^3); volume percent of Methanol and m% of water can be determined
• 2 mol of KCl is dissolved in 8 moles of water; mole fraction of KCl can be determined
• 25 g of NaF is mixed with 200g of H2O; mole fraction of NaF in the solution can be determined
• 15 g of NaBr is dissolved in 400 mL of solution; molarity of the solution can be determined

Explore the key physical properties of solutions, including the roles of solutes and solvents in homogeneous mixtures. Learn about different types of solutions based on physical states, with examples of gaseous and liquid solutions.