Acids, Bases and Reaction Rates

And others…

For thousands of years people have known that vinegar, lemon juice and many other foods taste sour.

However, it was not until a few hundred years ago that it was discovered why these things taste sour – They taste sour because they are all acids.

The term acid, in fact, comes from the Latin term acere, which means "sour"

Acids have a PH of less than 7.

Acids taste sour

Acids are corrosive to metals

Acids can ‘burn' your skin

Acids change litmus paper red

Litmus paper helps to determine acids and bases

Acids become less acidic when mixed with bases.

orange juice, lime juice or lemon juice (citric acid)

vinegar (acetic acid) aspirin (salicylic acid) yogurt (lactic acid) Coca-Cola (phosphoric acid) toilet bowl cleaner (sulfuric acid) bathroom cleaner (muriatic acid) wine (tartaric acid and/or malic acid) vitamin C tablets (ascorbic acid) urine (uric acid)

Bases can also be called alkalis.

Bases can be thought of as the chemical opposite of acids.

A reaction between an acid and base is called neutralization We will talk more

about this tomorrow

An example of base: soap

Bases have a pH more than 7 Bases feel slippery

Converts fats and oils in skin to glycerin (slick feel)

In a sense, bases dissolve your skin… think of getting Clorox bleach on your skin

Bases turns litmus paper to a blue color. Bases become less basic when mixed

with acids. Bases reacts with acids to form salt and water

Mustards Many medicines

Ie. Magnesium oxide – treats indigestion Bleaches, soaps, toothpastes, window

cleaners and other cleaning agents Sodium Hydrogen Carbonate (bread soda). Sodium hydroxide (NaOH) or caustic soda Calcium hydroxide ( Ca(OH)2 ) or limewater Ammonium hydroxide (NH4OH) or ammonia water Magnesium hydroxide ( Mg(OH)2 ) or milk of

magnesia

Measure of how acidic or how basic

More Acidic More Basic

HCl

Stomach Acid

Lemon Juice

Vinegar

Soda

Rain NaOH

Pure water Egg

Whites

Baking Soda

Drano

Mineral Lime

Ammonia

Tums

ACIDS 1 - HCL 2 – Stomach Acid 3 – Lemon Juice 4 - Vinegar 5 - Soda 6 – Rain Water

BASES 8 – Egg Whites 9 – Baking Soda 10 - Tums 11 - Ammonia 12 – Mineral Lime 13 - Drano 14 - NaOH Neutral:

7 – Pure Water

Acids and Bases… and others

Acids start with “H”

Examples: HCl H2SO4

Bases end in “OH” (hydroxides)

Examples: NaOH Ca(OH)2

Metals are single elements found on the left side of the periodic table Separated from non-metals by

metalloids (staircase)

Examples Al Li Can you name any other ones?

Carbonates end with the elements “CO3”

Examples Na2CO3

MgCO3

Salts are two elements bonded together from opposite sides of the periodic table or with a polyatomic ion What is polyatomic ions?

Examples NaCl AlF3

KNO3

How do we know which chemicals are… Bases? Acids? Carbonates? Salts? Metals?

Chemicals:NaCl HCl Li2CO3

Mg KOH AgMgCO3 BeF2

Al(OH)3

Groups:Metals Acid Bases Carbonates Salts

Group (Periodic Table)

Example

Charge

Why?

Alkali metal Alkaline earth metal Nitrogen groupChalcogensHalogens

Let’s practice:

Lithium iodide

Magnesium hydroxide

Hydrogen gas

Sodium

Calcium carbonate

___ NaNO3 + ___ PbO ___ Pb(NO3)2 + ___ Na2O

___ AgI + ___ Fe2(CO3)3 ___ FeI3 + ___ Ag2CO 3 

 

Acid is a compound, metal is an element… So what type of reaction?

HCl + Li _________ + __________

HF + Mg _________ + _________ H2S + Al _________ + _________

Therefore…Acid + Metal salt + H2

Acid is a compound, carbonate is an compound… So what type of reaction?

HCl + MgCO3 ________ + _________

HI + Li2CO3 ________ + ________

H2S + Na2CO3 _______ + _________

Acid + Carbonate salt + CO2 + H2O

What distinguishes acids?

What distinguishes bases?

Acid is a compound, base is an compound… So what type of reaction?

__ HCl + __ NaOH __ NaCl + __ HOH H2O

__ HF + __ Ca(OH)2 __Ca F2 + __ H2O

Acid + Base salt + H2O

Neutralizing an acid or base

MA x VA = MB x VB

M = molarity V = volume A = acid B = base

If you add 10mL of acid to 20mL of a .10M basic solution, what will the molarity of the acid be?

MA x VA = MB x VB

Lets look at volume and molarity… Less concentrated, we need more More concentrated, we need less