Acids, Bases , & Solutions

Acids, Bases , & Solutions

SolutionsSolution-uniform mixture that contains a

solvent & solute Solvent-the part of the solution that is present in the

largest amount Solute-the part of the solution that is present in the

smaller amount and is dissolved…

Water is the universal solvent, but solvents and solutes may be solids, liquids, or gases

Solutions have the same properties throughout

Colloids

a mixture that contains small undissolved particles, particles are too small to be seen, but large enough to scatter light

Suspension

Does not have the same properties through out

Contains visible particles

Effects of Solute & Solvents

Solutes lower the freezing point & raise the boiling point of a solvent

Particles in SolutionWhen a solution forms, particles of the

solvent surround and separate the particles of the solute.

Ionic and molecular compounds in solution

Ionic – positive and negative ions are attracted to the polar water molecules. These types of compounds in water will conduct electricity.

Molecular – breaks up into individual neutral molecules (sugar)

Common solutionsSolute Solvent Solution

Gas Gas Air (oxygen and other gases in nitrogen)

Gas Liquid Soda water (carbon dioxide in water)

Liquid Liquid Antifreeze (ethylene glycol in water)

Solid Liquid Dental filling (silver in mercury)

Solid Liquid Ocean water (sodium chloride in water)

Solid Solid Stainless steel (chromium, nickel, and carbon in iron)

ConcentrationConcentrated solution-lots of

solute, little solventEx. Frozen juice

Dilute solution-little solute, lots of solventEx. Frozen juice + water

Measuring concentration-compare amount of solute to solventEx. 5 grams per 100mL

SolubilityHow much solute can dissolve in a solvent at

a given temperatureUnsaturated-can hold more soluteSaturated-can NOT hold more soluteSupersaturated-too much solute, some is

undissolved at the bottom of the container

Factors affecting solubilityPressure

Increasing the pressure increases the solubility and vise-versa

Type of solventSome solutes & solvents are

incompatibleEx. Oil and vinegar

The solvent affects the solubility of a substance

Ex. Oil-based paint & water

TemperatureIncreasing the temp. of a solid

increases the solubilityIncreasing temperature of a gas

decreases the solubility

Acids and BasesAcids and Bases

Chemicals may be classified as acids or bases.

Things that are neither acids nor bases are neutral.

pH measures the acidicity or basidity of a solution

AcidsTaste sourTurns blue litmus paper redReacts with metals/carbonatesContains hydrogen ions H+

Examples:Lemon juiceVinegarCar battery acid (dangerous!)

Some of our favorite foods make our tongue curl up because they are SOUR.

Acids and BasesAcids and Bases

Bases Taste bitter Feel Slippery Turns red litmus paper blue Contains hydroxide ions OH-

Turns Phenolphthalein pink Examples:

Milk Baking soda Soap Drain cleaner (dangerous!)

Bitter!

Some foods have a “bite” of their own because they’re somewhat bitter.

pH A special name given

to the acid or base characteristic is called: pH

How Do We Measure pH?

We measure pH by using special strips of paper called pH paper

How Does It Work? The paper is treated with

chemicals that change color to show the pH.

When the paper touches the substance being tested, it turns a specific color to tell if the substance is an acid or a base.

The pH ScalepH scale ranges from 0 -14pH 7 is neutral; neither acid nor basePure water is pH 7Low pH = acidHigh pH = baseThe closer to the ends of the scale, the

stronger the solution

Acid

Any substance which has a pH value less than 7 is considered an acid

0--------------7---------------14

Acid Neutral Base

Base

Any substance which has a pH value greater than 7 is a base

0--------------7---------------14

Acid Neutral Base

pH 7

A pH of 7 is called neutral—neither acid nor base.

0-------------7------------14

Acid Neutral Base

The pH Scale

The pH Scale Each pH unit is 10 times as large as the

previous one A change of 2 pH units means 100 times more

basic or acidic

Each pH unit is 10 times as large as the previous one

A change of 2 pH units means 100 times more basic or acidic

x10 x100

Acid-Base Reactions

Neutralization-a reaction in which an acid reacts with a base to produce salt and water

HCl + NaOH= H2O + NaCl