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