Introduction to Solutions. Matter Flowchart MATTER Can it be physically separated? Homogeneous Mixture (solution) Heterogeneous MixtureCompoundElement.

Introduction to Solutions

Matter Flowchart

MATTER

Can it be physically separated?

Homogeneous Mixture

(solution)

Heterogeneous Mixture Compound Element

MIXTURE PURE SUBSTANCE

yes no

Can it be chemically decomposed?

noyesIs the composition uniform?

noyes

Colloids Suspensions

Pure Substances• A pure substance has a

definite composition.• Pure substances can be

elements or compounds

Mixtures• A mixture can be either homogeneous or

heterogeneous.

• A homogeneous mixture is one in which all of the components are UNIFORMILY distributed.– Ex: chocolate milk

• A heterogeneous mixture is one in which the components are NOT UNIFORMILY distributed.– Ex: pizza

HOMOGENEOUS HETEROGENEOUS

SolutionsSolutions, in chemistry, are homogeneous

mixtures of two or more substances.

The substance present in largest quantity usually is called the solvent. The solvent can be either a liquid or a solid.

The substance that is present in smallest quantity is said to be dissolved and is called the solute. The solute can be either a gas, a liquid, or a solid.

Coke lists as its ingredients as: “carbonated water, high fructose corn syrup and/or sucrose, caramel color, phosphoric acid, natural flavors, caffeine”.

What is the solvent?

What are the solutes?

What can we classify CO2 as in carbonated beverages?

Concept Check

• Miscible liquids can easily dissolve in one another.

• Immiscible liquids are not soluble in each other.

IPC-Solutions-Borders

Heterogeneous Mixtures

Suspensions-a heterogeneous mixture that contains large particles that “settle out” unless constantly stirred or agitated Ex: freshly squeezed OJ, salad dressing

Colloids-a heterogeneous mixture in which the components are microscopic and will not separate when left standing. Ex: mayonnaise, milk, stick deodorant

How does a solid dissolve into a liquid?

• Solvent molecules are attracted to surface ions.• Each ion is surrounded by solvent molecules.

Ionic solid dissolving in water

Dissolution vs. Reaction

• Dissolution is a physical change—you can get back the original solute by evaporating the solvent.

• If you cant, the substance didn’t dissolve, it reacted.

Ni(s) + HCl(aq) NiCl2(aq) + H2(g) NiCl2(s)dry

Factors Affecting Solubility

• Chemists use the saying “like dissolves like:”Polar substances tend to

dissolve in polar solvents.Nonpolar substances tend

to dissolve in nonpolar solvents.

Oil is nonpolar while water is polar. They are immiscible.

Saturation Types• Saturated• Unsaturated

Degree of saturation

• Unsaturated SolutionLess than the

maximum amount of solute for that temperature is dissolved in the solvent.

No solid remains in flask.

Degree of saturation• Saturated solution

Solvent holds as much solute as is possible at that temperature.

Undissolved solid remains in flask.

Dissolved solute is in dynamic equilibrium with solid solute particles.

Saturated Solution


Degree of saturation

• Supersaturated SolutionSolvent holds more solute than is normally

possible at that temperature.These solutions are unstable

Chemistry-Borders

Temperature and Solubility

Generally, the solubility of solid solutes in liquid solvents increases with increasing temperature.

Solubility

What amount of CaCl2 can be dissolved in 100 g H2O at 20° C?

ANSWER: 75 g CaCl2

Let’s play a quick game of….

Chemistry-Borders IPC-Solutions-Borders

Saturated or Unsaturated?

• a solution that contains 70g of NaNO3 at 30°C


Unsaturated!



• a solution that contains 50g of NH4Cl at 50°C


saturated!



• a solution that contains 20g of KClO3 at 50°C


saturated!



• a solution that contains 70g of KI at 0°C


Unsaturated!



• A mass of 100 g of NaNO3 is dissolved in 100 g of water at 80ºC


Unsaturated!


THE END


Solubility of Gases

• In general, the solubility of gases in water increases with increasing mass.

Why?• Larger molecules

have stronger dispersion forces.


Gases in Solution

• The solubility of liquids and solids does not change appreciably with pressure.

• But, the solubility of a gas in a liquid is directly proportional to its pressure.

Increasing pressure above solution forces more gas to dissolve.


Temperature• The opposite is true of

gases. Higher temperature drives gases out of solution.

Carbonated soft drinks are more “bubbly” if stored in the refrigerator.

Warm lakes have less O2 dissolved in them than cool lakes.



Solid solubility and temperature

solubility increases with increasing temperature

solubility decreases with increasing temperature



Gas solubility and temperature

solubility usually decreases with increasing temperature


Electrolytes


Electrolyte

Electrolyte: a substance that dissolves in water to give a solution that conducts electric current

•Any soluble ionic compound is an electrolyte

•Strong acids are electrolytes


Introduction to Solutions. Matter Flowchart MATTER Can it be physically separated? Homogeneous Mixture (solution) Heterogeneous MixtureCompoundElement.

Documents

solid dissolve

solutions ipcsolutions

solid solute particles

dissolved solute

original solute

solvent molecules

undissolved solid remains

solubility of solid