Solutions

Definitions: solutions A solution is a HOMOGENEOUS mixture of 2 or more substances mixed evenly at molecular level.. One part is regarded as the SOLUTE and the others as SOLVENT

Parts of a Solution Solute-the part that gets dissolved Solvent-the part that does the dissolving

Parts of a Solution Solute Solvent Example solid Alloys (brass, steel) liquid Salt water gas Air bubbles in ice cubes “suicides” (mixed drinks) Soft drinks Air SOLUTE –material being dissolved (usually the lesser amount) SOLVENT – material doing the dissolving (usually the greater amount) Solute + Solvent = Solution

Solution Definitions Soluble - capable of being dissolved 2. Solution – homogeneous mixtures 3. Saturated – exactly the right amount of dissolved solute for a particular solvent 4. Unsaturated –less solute than can be dissolved by a solvent to be saturated 5. Supersaturated -more dissolved solute than saturated. Has to be specially made; unstable

3 Factors that increase rate of Dissolving for solids in a liquid solution 1. Surface area - Increase of surface area increases rate of dissolving. Increase surface area by breaking/grinding solid 2. Agitation – Shaking/stirring a solution will increase the rate of dissolving 3. Heat- increase in temperature usually increases the rate of dissolving

2 factors that increase the rate of dissolving for a gas in a liquid 1. Temperature- increase in temperature usually decreases the rate of dissolving 2. Pressure- Increase in pressure increases the rate of dissolving. ***Pressure has little/no effect on the dissolving rate of a solid in a liquid***

Factors Affecting Solubility 1. Types of solvents and solutes a. “Like dissolves like” A polar solvent, such as water, will dissolve polar and ionic solutes. Nonpolar solvents, such as oils, will dissolve other nonpolar solutes. 2. Pressure a. Liquids and solids little to no effect b. Gases - solubility increase with increased pressure c. Henry’s law - solubility of a gas in a liquid is directly proportional to the partial pressure of that gas on the surface of the liquid Ex: carbonated beverages. 3. Temperature Liquids and solids - increase temperature increase solubility (mostly) b. Gases - increase temperature decrease solubility

Some solutions conduct electricity, some don’t Electrolytes – compounds that conduct an electric current in an aqueous solution OR in the molten state. An electrolyte solution contains charged particles (ions), which can move. Any salt dissolved in water is an electrolyte: NaCl, KI, etc.

Types of Electrolytes Strong electrolytes– a large portion of the solute exists as ions, such as aqueous solutions of all ionic compounds Weak electrolytes– these are solutions in which only a small portion of the solute exists as ions Non-electrolytes- compounds that do NOT conduct electricity in either aqueous solution of melted distilled water Gases molecular compounds (2 nonmetals) organic compounds – alcohols, sugars, etc. anything containing a carbon.

Identify the solute and solvent in the following solutions: Practice: Identify the solute and solvent in the following solutions: 10.0 g of sugar & 40.0 g of water solute: ____________solvent: ___________ b) 75 g of KBr & 100 g water

a) 50 g KCl in 100 g of water at 90°C. ____ 3. Based on the solubility chart below, decide whether each of the following is U: unsaturated(Under line), S: saturated (on line), SS: supersaturated (above line), or N: not enough information is given. a) 50 g KCl in 100 g of water at 90°C. ____ b) 50 g KCl in 100 g of water at 60°C. ____ d) 50 g KNO3 in 50 g of water at 60°C. ____ 50 g KNO3 = X X = 100 50 g water 100 g water

5. Circle the correct type for the following solutions: Practice: 5. Circle the correct type for the following solutions: a) NaCl (aq): electrolyte or nonelectrolyte b) CCl4 (l): electrolyte or nonelectrolyte