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Solutions:. A homogeneous mixture of two or more substances combined into a single phase. Solute - material being dissolved Solvent - dissolving medium Solution process: Solute + Solvent Solution. Types of solutions. Figure 1.3 defines various types of solutions.
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Solutions: A homogeneous mixture of two or more substances combined into a single phase. Solute- material being dissolved Solvent- dissolving medium Solution process: Solute + Solvent Solution
Types of solutions • Figure 1.3 defines various types of solutions. • Identify which type of solutions is represented below:
Types of Mixtures: • Solution • A homogeneous mixture of two/more substances uniformly dispersed in a single phase. • Suspension • Contains large particles that will not stay suspended unless stirring is continued. • Colloid Intermediate - small particles that remain evenly dispersed throughout the mixture. Exhibts the Tydnall effect (scatters beam of light). • Emulsion – a colloidal dispersion (liquid/liquid)
Tyndall effectIdentification of a colloid • Light passed through a sample is scattered due to the presence of small particles.
Solution Process • Factors that affect the rate of solution: • Surface area • Stirring/mixing • Temperature • Solute + Solvent Solution
Solution Process:Dissolving –vs- Dissociation • Ionic compounds- dissociate in water to give electrolytes (conductive ions). • Covalent molecules – dissolve in water to give nonelectrolytes (not-conductive compounds).
Solution Process:Solubility • Solubility – defines the amount of solute that can be dissolved as: Grams solute/ 100 g H2O • Factors that affect the solubility (amount) of solute that can dissolve in a solvent: • Temperature • nature of the material- “likes dissolve likes” • Pressure
Solution Process & Solubility • Factors that affect the solubility of a solution • Immiscible – liquids that are not soluble in each other (ex: oil & water) • Miscible – liquids that are soluble in each other (ex: methanol & water)
Types of Solutions: • Saturated solution= contains the maximum amount of solute for a given amount of solvent. [solute + solvent solution] • Unsaturated solution= contains less than the maximum amount of solute for a given amount of solvent. • Supersaturated solution = contains more than the maximum amount of solute for a given amount of solvent.
Solubility Curves • In most cases, increasing the temperature of a solid/liquid solution will increase the solubility. • Solubility is defined as g solute/100g H2O for aqueous solutions.
Measurement of Solution Concentration:Molarity (M) Molarity (M) = moles Solute Liter Solution • Similar to density calculations. • Possible conversions: • Gram mole (using molar mass) • mL Liter ( 1000 mL = 1 Liter)
Measurement of Solution Concentration:Molality (m) Molality (m) = moles Solute Kg Solvent
Practice! • Determine the molarity of a solution that contains: • 0.25 moles of KI in 750 ml solution. • 34.0 g of NaOH in 1 liter solution. • Determine the molality of a solution that contains: • 0.25 moles of NaCl in 500g of water. • 34.0 g of NaOH in 1 Kg water.
Practice-Molarity • Using molarity/molality in a calculation: • How many grams of CaCl2 are required to make 500mL of a 0.5M solution? • How much water (Kg) is needed to prepare a 1.0m solution of 50.0g of NaOH?