acids, bases, & salts (1)

7/27/2019 Acids, Bases, & Salts (1)

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Acids, Bases, & Salts


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What is an ACID?pH less than 7

Neutralizes bases

Forms H + ions in solution

Corrosive-reacts with most

metals to form hydrogen gas Good conductors of electricity


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Acids Generate Ions

HNO3 + H2O H3O+ + NO3


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Weak vs. Strong Acids

Weak Acids do not ionize completely:

Acetic, Boric, Nitrous, Phosphoric,

Sulfurous

Strong Acids ionize completely:

Hydrochloric, Nitric; Sulfuric, Hydriodic


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Common Acids

HCl- hydrochloric- stomach acid

H2SO4- sulfuric acid - car batteries

HNO3

nitric acid - explosives

HC2H3O2- acetic acid - vinegar

H2CO3-carbonic acidsodas

H3PO4- phosphoric acid -flavorings
http://agitator.dynip.com/agitator/Generator/interstate.jpghttp://www.funset.com/images/pepsi.gifhttp://users.erols.com/interlac/homehy/vinegar.jpg


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http://www.thebird.org/store/clean/internal/acidsam.gif


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What is a BASE?

pH greater than 7

Feels slippery

Dissolves fats and oils

Usually forms OH-ions in

solutionNeutralizes acids


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Weak vs. Strong Bases

Weak Bases: ammonia; potassium

carbonate, sodium carbonate

Strong Bases: sodium hydroxide; sodium

phosphate; barium hydroxide; calcium

hydroxide


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Common Bases

NaOH- sodium hydroxide (LYE) soaps, drain cleaner

Mg (OH)2 - magnesium hydroxide-antacids

Al(OH)3-aluminum hydroxide-antacids, deodorants

NH4OH-ammonium hydroxide- ammonia
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Types of Acids and Bases

In the 1800s chemical concepts were based on the

reactions of aqueous solutions.

Svante Arrhenius developed a concept of acidsand bases relevant to reactions in H2O.

Arrhenius acidproduces hydrogen ions in water. Arrhenius baseproduce hydroxide ions in water.


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A broader ,more modern concept of acids and

bases was developed later.

Bronsted-Lowry acid- donates a hydrogen ion

in a reaction.

BronstedLowry baseaccepts a hydrogen

in a reaction.


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Conjugate acid- compound formed when an

base gains a hydrogen ion.

Conjugate basecompound formed when

an acid loses a hydrogen ion.


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pH Scale
http://bcn.boulder.co.us/basin/data/COBWQ/info/pH.gif


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pH of Common Substances

Timberlake, Chemistry 7th Edition, page 335
http://d/chemistry%20file/Acids,%20Bases,%20&%20Salts.ppt


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Reactions with indicators

Indicator Acid

color

Neutral

color

Base

color

Phenolphthalein Colorless Faint pink Dark pink

Bromthymol

blue

Yellow Green Blue

Litmus Red ----- Blue


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pH paper

pH paper changes

color to indicate a

specific pH value.
http://images.google.com/imgres?imgurl=http://www.chem.ucla.edu/~gchemlab/ph-paper.jpg&imgrefurl=http://www.chem.ucla.edu/~gchemlab/lab_hardware_web.htm&h=315&w=375&sz=11&hl=en&start=2&tbnid=M6BvJEJBykPVhM:&tbnh=102&tbnw=122&prev=/images%3Fq%3DpH%2Bpaper%26gbv%3D2%26hl%3Den%26safe%3Dactive%26sa%3DG


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Buffers

A buffer is a solution that resists changes in

pH when small amounts of acids and bases

are added.


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Situations in which pH is controlled

Heartburn

Planting vegetables and flowers

Fish Tanks and Ponds

Blood

Swimming pools


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Acids and Bases in Solution

HCl + H20 H3O + + Cl-(more hydronium ions, more acidic)

NaOH in water Na+ + OH-

(more hydroxide ions, more basic) NaOH + HCl NaCl + HOH

Acid + Base yields type of salt and water

NH3 + H20 NH4+ + OH-ammonia gas + water yields ammonium and

hydroxide ions


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Acid Rain

Pollution in the air (sulfur dioxide, carbon

dioxide, nitrogen dioxide) combines with

water to form various acids..


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Rapid changes in pH can kill fish

and other organisms in lakes and

streams.

Soil pH is affected and can kill

plants and create sinkholes


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What is a SALT? A salt is a neutral substance produced from the

reaction of an acid and a base.

Composed of the negative ion of an acid and the

positive ion of a base. One of the products of a Neutralization Reaction

Examples: KCl, MgSO4, Na3PO4
http://www.genhealth.com/salt.jpghttp://www.bonaire-travelguide.com/sights/photos/salt-index.jpghttp://www.vermontsoap.com/images/bathsalts.jpg


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Neutralization Reaction

A neutralization reaction is the reaction of

an acid with a base to produce salt and

water. Example

H2SO4 + NaOH NaHSO4 + H2O


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Digestion and pH

Digestion-process by which foods are broken down

into simpler substances.

Mechanical digestion-physical process in which food

is torn apart (mouth)

Chemical digestion- chemical reactions in which large

molecules are broken down into smaller molecules.

(stomach and small intestines)
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pH in the Digestive System

Mouth-pH around 7. Saliva contains amylase, an

enzyme which begins to break carbohydrates into

sugars. Stomach- pH around 2. Proteins are broken down

into amino acids by the enzyme pepsin.

Small intestine-pH around 8. Most digestion ends.

Small molecules move to bloodstream toward

cells that use them


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mouth

esophagus

stomach

small intestine

large intestine

Digestive system
http://fairmanstudios.com/images/digestive_sys.jpg


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Acids, Bases, and Salts

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acids, bases, & salts (1)

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