Mixtures & Solutions

Mixtures &Solutions Chapter 7

Distinguish between homogeneous and hetereogeneous mixtures. • Compare the properties of suspensions, colloids, and solutions. • Determine how things dissolve. • Examine the factors that affect the rate at which substances dissolve. • Compare and contrast saturated, unsaturated, and supersaturated solutions. • Examine how some solutes break apart in water solutions to form positively and negatively charged particles. • Determine how some substances conduct electricity. Students Will Be Able To:

Earth known as “blue planet” since most of it is water • Expands as it freezes • Ice less dense than liquid water • Reason why water floats on top of rivers and lakes • Is neutral- 10 protons and 10 electrons • Is polar • Uneven distribution of electrons between oxygen and hydrogen atoms Water

Attraction of atoms to a hydrogen atom Seen with water molecule Are not as strong as covalent and ionic bonds Are the strongest of the bonds that can form between molecules Hydrogen Bonds

Water can have up to four hydrogen bonds at the same time • Responsible for many properties such as cohesion and adhesion • Cohesion- attraction of same substances • Adhesion- attraction of different substances Cohesion and Adhesion

Is the combination of two or more substances that are not chemically combined • 2 types • Homogenous • Heterogenous Mixtures

Are large particles • Composed of dissimilar substances • Individual substances can be separated Heterogenous Mixtures

Are small particles • Are the size of a molecule • Composed of similar substances • Results in a uniform composition • Also known as a solution Homogenous Mixtures

Is a mixture in which particles of a material are more or less evenly dispersed throughout a liquid or gas • Particles will eventually settle to the bottom Suspensions

Is a homogenous mixture of two or more substances uniformly dispersed throughout a single phase • Has 2 parts • Solvent • Is the substance that dissolves the solute • Solute • Is the substance being dissolved Solutions

Aqueous solutions are those solutions in which water is the solvent • Alloys are solutions • Involve 2 solids • Brass • Made from copper and zinc • Bronze • Made from copper and tin • Steel • Made from iron and carbon Solutions

Is a mixture consisting of tiny particles that are intermediate in size between those in solutions and those in suspensions and that are suspended in a liquid, solid, or gas • Typically have an electric charge • Particles are like-charged resulting in repulsion • Causes them not to settle out Colloids

Is the amount of a particular substance in a given quantity of a solution • The more concentrated the solution, the more the solute • The less concentrated the solution, the less the solute Concentration

Is the ability of one substance to dissolve into another at a given temperature and pressure • Is expressed in terms of the amount of solute that will dissolve in a given amount of solvent to produce a saturated solution Solubility

Occurs only when both substances are polar or nonpolar • When both substances are different in polarity, the solute will not dissolve Solubility

Substances can either be water-soluble or fat- soluble Solubility

Water-soluble • Occurs with two polar substances • Results in it dissolving in water • Vitamin C is an example • Can not be produced by the human body • Must be obtained from external sources such as food • Functions in producing collagen • Makes bones strong • An excess of vitamin C is removed by kidneys • Can not overdose on it Solubility

Fat-soluble • Occurs with 2 nonpolar substances • Results in it dissolving in fats and oils • Vitamin A is an example • Must be obtained from yellow, leafy vegetables • Function in normal vision, growth of bones and skin • Too much vitamin A in the body results in toxicity Solubility

Miscible vs immiscible • Miscible describes two or more liquids that are able to dissolve into each other in various proportions • Immiscible describes two or more liquids that do not mix with each other • Results in layers forming Solubility

Solubility occurs at the surface of solid particles • Therefore, the solid has to be broken into smaller pieces so they can uniformly combine with the solvent molecules Solubility of Solids

Greater surface area • Due to breaking of solid particles • Increased temperatures • Solvent particles can dissolve more solute particles • Shaking/stirring • Helps break solid particles • Solubility rules • Depends on solute and solvent Factors Affecting Solubility

Is the separating of a molecule into simpler molecules, atoms, radicals, or ions • Occurs with ionic compounds • Involves hydration • Due to water being the solvent Dissociation

3 main types • Unsaturated solutions • Contains less solute than a saturated solution does and is able to dissolve addition solute • Saturated solutions • Is not capable of dissolving any more solute under the given conditions • Supersaturated solutions • Holds more dissolved solute than is required to reach equilibrium at a given temperature Types of Solutions

In a saturated solution, solute particles are dissolving at the same rate • Said to be at dynamic equilibrium • When the amount of solute has reached its solubility limit, the particles in solution are in dynamic equilibrium with excess solute • Results in dissolution and crystallization occurring at equal rates • Said to be at solubility equilibrium Solubility Equilibrium

Is the ability to conduct an electric current • Dependent on whether it contains charged particles • Particles must be able to move Conductivity

Is a substance that dissolves in water to give a solution that conducts an electric current • Can be strong or weak • Strong electrolytes dissociate completely • Weak electrolytes dissociate partially Electrolytes

Is a liquid or solid substance that does not allow the flow of an electric current, either in solution or in its pure state Nonelectrolytes

Mixtures & Solutions