Acids & Bases• In Biological Systems

• In Domestic Applications

• In Industrial Processes

Biologicals

ACID-BASE NEUTRALIZATION

• Neutralisation Reaction

Acid + Base Salt + Water

HCl + NaOH NaCl + H2O

H+ + OH – H2O

Important – To neutralize an solution concentrations of acids and base must be equal

Antacids

~ Neutralise excess stomach acid~ Raise stomach pH > 4Pepsin inactive~ Assist with ulcer treatment

~ solubility in H2O but still produce high % of ions

Always check for side effects!

Other Examples~

Mg(OH)2 Milk of Magnesia

2HCl + Mg(OH)2 MgCl2 + 2H2O

Al(OH)3 In Mylanta

3HCl + Al(OH)3 AlCl3 + 3H2O

Calcium Carbonate (Tums) CaCO3

2HCl + CaCO3 CaCl2 + H2O + CO2 (g)

~Also a Ca 2 + supplement

Long term overuse Ca 2 + levels risk kidney stones (renal calculi)

NaHCO3 Baking Soda

Not recommended!!

HCl + NaHCO3 NaCl + H2O + CO2 (g)

Stomach can ‘explode’

Citrus Fruits

• Fruits like: Lemons, Limes, and Oranges– Good source of Citric Acid

• Used in many processes– Krebs Cycle (Produces intermediates for ATP

production)– Cleaning Supplies (breakdown of proteins)– Photography– Foods and beverages– Medical (sooth the pain of bee stings)– Construction – And Much, much more

Citrus Fruits Continued

• Also a great source of L-ascorbic acid– Better known as Vitamin C

• Coenzyme in at least metabolic pathways– Most notable in collagen synthesis

» Deficiency = Scurvy

• An essential nutrient for humans• An antioxidant helpful in fighting disease

04/20/23 9

Your Digestive Track

• Salvia in your mouth is slightly alkaline7.5 and Amylase slightly acidic 6.7 – Both aid to begin the breakdown of ingested foods

• Hydrochloric Acid in your stomach– Provides the environment in your stomach for

pepsinogen to break down proteins into peptides• Bile Acids from your gall bladder

– Are critical for digestion and absorption of fats and fat-soluble vitamins in the small intestine.

04/20/23 10

Buffering Systems

• Buffering systems consist of an acid and its conjugate base and maintain pH

• Many chemical reactions require specific pH to occur properly– Additionally, proteins and enzymes involved in

our metabolic pathways can be denatured (destroyed) if the pH of our blood and other fluids are not maintained

04/20/23 11

Your Buffering Systems

• There are three primary systems that regulate the H+ concentration in the body fluids to prevent acidosis or alkalosis: – (1) the chemical acid-base buffer systems of the body fluids, which

immediately combine with acid or base to prevent excessive changes in H+ concentration;

– (2) the respiratory center, which regulates the removal of CO2 (and, therefore, H2CO3) from the extracellular fluid

– (3) the kidneys, which can excrete either acid or alkaline urine, thereby readjusting the extracellular fluid H+ concentration toward normal during acidosis or alkalosis.

Domestic Applications

04/20/23 13

Detergents and Household Cleaning Products

• Many laundry detergents and cleaners use acids or bases.– Most cleaning agents that are used in cleaning your

laundry are alkaline.• This aids in the removal of the acidic GUNK that gets on your

clothing without rubbing. • Soluble salts of an alkali metal like potassium or sodium are

good grease removers.• They form an emulsion of the oily or solid particles that are

held in suspension. The particles do not separate from the liquid and do not redeposit on the fabric. Essentially trapping the unwanted dirt and oils

04/20/23 14

Some Common Alaline Detergents

• Tide (pH 9)

• Bleach (pH 12.5)

• Borax (pH 9.5)

• Lye (pH 13)

• Alkaline substances vary in their strength with the strongest causing burns and internal injuries if swallowed

04/20/23 15

Acidic Cleaners

• Many household cleaners are acidic. These include, but are not limited to:– toilet bowl cleaners – drain and metal cleaners– anti-rust products– some swimming pool chemicals.

• Not all of the brands of these items are acidic.

04/20/23 16

Household Cleaners

• Household cleaners can have a variety or acids and bases found on their labels– Lysol Toilet Cleaner for example (pH 1)

• What do you think the active ingredient is?

• HCl – Hydrochloric Acid

04/20/23 17

Acidic Cleaners Continued

– Acidic agents are used to remove hard-water deposits and discoloration from metal stains

– The most acidic household agents will also eat away at clothing and cause irritation to the skin, and should not be used on all surfaces.

04/20/23 18

Ammonia and Bleach

• Two common ingredients found in household cleaning products are ammonia and bleach

• The dangers occur when using chemicals without reading the labels first

• That warning is there to protect you. Household bleach has a chemical formula of NaOCl

• Ammonia NH3

04/20/23 19

The Reaction

• 2NaOCl + 2NH3 --> 2NaONH3 + Cl2• Do you see the diatomic molecule produced?• Chlorine Gas is deadly if inhaled

– Cl2 is so deadly it was used as a chemical weapon during World War I and later by Nazi Germany in World War II)

• Another potential reaction– 3NaOCl + NH3 --> 3NaOH + NCl3

• This one just blows up in your face; no need to explain the danger here

04/20/23

Industrial Uses

04/20/23 21

Many Uses in Industry

• Catalysts in Reactions– Synthesis of Esters

• These are the flavors and fragrances your senses crave

• Also likely found on at least on clothing label you are wearing right now

• An acid and it conjugate base can be used to buffer reactions in industry – Certain reactions require as specific pH, If an acid

and its conjugate base are present reaction pH remains constant

04/20/23 22